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Title: Illusions - A Psychological Study
Author: Sully, James, 1842-1923
Language: English
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The present volume takes a wide survey of the field of error, embracing
in its view not only the illusions of sense dealt with in treatises on
physiological optics, etc., but also other errors familiarly known as
illusions, and resembling the former in their structure and mode of
origin. I have throughout endeavoured to keep to a strictly scientific
treatment, that is to say, the description and classification of
acknowledged errors, and the explanation of these by a reference to
their psychical and physical conditions. At the same time, I was not
able, at the close of my exposition, to avoid pointing out how the
psychology leads on to the philosophy of the subject. Some of the
chapters were first roughly sketched out in articles published in
magazines and reviews; but these have been not only greatly enlarged,
but, to a considerable extent, rewritten.
                                                          J. S.

  _Hampstead, April, 1881._




  Vulgar idea of Illusion, 1, 2; Psychological treatment of subject,
  3, 4; definition of Illusion, 4-7; Philosophic extension of idea,
  7, 8.



  Popular and Scientific conceptions of Mind, 9, 10; Illusion and
  Hallucination, 11-13; varieties of Immediate Knowledge, 13-16; four-fold
  division of Illusions, 16-18.



  _Psychology of Perception_:--The Psychological analysis of Perception,
   19, 20; Sensation and its discrimination, etc., 20, 21; interpretation
   of Sensation, 22, 23; construction of material object, 23, 24;
   recognition of object, specific and individual, 24-27; Preperception
   and Perception, 27-31; Physiological conditions of Perception, 31-33;
   Visual and other Sense-perception, 33, 34.

  _Illusions of Perception_:--Illusion of Perception defined, 35-38;
   sources of Sense-illusion, 38-40: (a) confusion of
   Sense-impression, 40-44; (b) misinterpretation of Sense-impression, 44;
   Passive and Active misinterpretation, 44-46; Passive Illusions as
   organically and extra-organically conditioned, 46-49.



  A. _Passive Illusions (a) as determined by the Organism._
  _Results of Limits of Sensibility_:--Relation of quantity of Sensation to
  that of Stimulus, 50-52; coalescence of simultaneous Sensations,
  52-55; after-effect of Stimulation, 55, 56; effects of prolonged
  Stimulation, 56-58; Specific Energy of Nerves, 58, 59; localization
  of Sensation, 59-62; Subjective Sensations, 62-64.

  _Results of Variation of Sensibility_:--Rise and fall of Sensibility,
  64-67; Paræsesthesia, 67, 68; _rationale_ of organically conditioned
  Illusions, 68, 69.



  A. _Passive Illusions (b) as determined by the Environment._
  _Exceptional Relation of Stimulus to Organ_:--Displacement of organ,
  etc., 70-72.

  _Exceptional Arrangement of Circumstances in the Environment_:--
  Misinterpretation of the direction and movement of objects, 72-75;
  misperception of Distance, 75, 76; Illusions of depth, relief, and
  solidity in Art, 77-81; Illusions connected with the perception of
  objects through transparent coloured media, 82-84; visual transformation
  of concave into convex form, 84-86; false recognition of
  objects, 86, 87; inattention to Sense-impression in Recognition,
  87-91; suggestion taking the direction of familiar recurring experiences,
  91, 92.



  B. _Active Illusions._

  Preperception and Illusion, 93-95.

  _Voluntary Preperception_:--Choice of interpretation in the case of
  visible movement, 95, 96; and in the case of flat projections of form,
  96-98; capricious interpretation of obscure impressions, 99, 100.

  _Involuntary Preperception_:--Effects of permanent Predisposition,
  101, 102; effects of partial temporary Preadjustment, 102-105;
  complete Pro-adjustment or Expectation, 106-109; subordination of
  Sense-impression to Preperception, 109-111; transition from Illusion
  to Hallucination, 111, 112; rudimentary Hallucinations, 112-114;
  developed Hallucinations, 114-116; Hallucination in normal life,
  116, 117; Hallucinations of insanity, 118-120; gradual development
  of Sense-illusions, and continuity of normal and abnormal life; 120-123;
  Sanity and Insanity distinguished, 123-126.



  Mystery of sleep, 127, 128; theories of Dreams, 128, 129; scientific
  explanation of Dreams, 129, 130.

  _Sleep and Dreaming_:--Condition of organism during sleep, 131, 132;
  Are the nervous centres ever wholly inactive during sleep? 132-134;
  nature of cerebral activity involved in Dreams, 134-136; psychical
  conditions of Dreams, 136-138.

  _The Dream as Illusion_:--External Sense-impressions as excitants of
  Dream-images, 139-143; internal "subjective" stimuli in the sense-organs,
  143-145; organic sensations, 145-147; how sensations are
  exaggerated in Dream-interpretation, 147-151.

  _The Dream as Hallucination_:--Results of direct central stimulation
  151-153; indirect central stimulation and association, 153-155.

  _The Form and Structure of Dreams_:--The incoherence of Dreams explained,
  156-161; coherence and unity of Dream as effected (a) by
  coalescence and transformation of images, 161-163; (b) by aground-tone
  of feeling, 164-168; (c) by the play of associative dispositions,
  168-172; (d) by the activities of selective attention stimulated by
  the rational impulse to connect and to arrange, 172-176; examples
  of Dreams, 176-179; limits of intelligence and rational activity in
  Dreams, 180-182; Dreaming and mental disease, 182, 183; After-dreams
  and Apparitions, 183-185.

  NOTE.--The Hypnotic Condition, 185-188.



  Illusions of Introspection defined, 189-192; question of the possibility
  of illusory Introspection, 192-194; incomplete grasp of internal
  feelings as such, 194-196; misobservation of internal feelings: Passive
  Illusions, 196-199; Active Illusions, 199-202; malobservation of
  subjective states, 202-205; Illusory Introspection in psychology and
  philosophy, 205-208; value of the Introspective method, 208-211.



  Emotion and Perception, 212; Æsthetic Intuition, 213; Subjective
  Impressions of beauty misinterpreted, 213-216; analogous Emotional
  Intuitions, 216, 217; Insight, its nature, 217-220; Passive Illusions
  of Insight, 220-222; Active Illusions of Insight: projection of
  individual feelings, 222-224; the poetic transformation of nature,
  224-226; special predispositions as falsifying Insight, 226-228;
  value of faculty of Insight, 228-230.



  Vulgar confidence in Memory, 231-233; definition of Memory, 233-235;
  Psychology of Memory, 235-237; Physiology of Memory, 237, 238;
  Memory as localization in the past, 238-241; Illusions of Memory
  classified, 241-245.

  (1) _Illusions of Time-Perspective_:--

  (a) Definite Localization of events: constant errors in retrospective
  estimate of time, 245-249; varying errors: estimate of duration
  during a period, 249-251; variations in retrospective estimate of
  duration, 251-256.

  (b) Indefinite Localization: effect of vividness of mnemonic image
  on the apparent distance of events, 256-258; isolated public events,
  258, 259; active element in errors of Localization, 259-261.

  (2) _Distortions of Memory_:--Transformation of past through
  forgetfulness, 261-264; confusion of distinct recollections, 264-266;
  Active Illusion: influence of present imaginative activity, 266-269;
  exaggeration in recollections of remote experiences, 269, 270; action of
  present feeling in transforming past, 270, 271.

  (3) _Hallucinations of Memory_:--Their nature, 271-273; past dreams taken
  for external experiences, 273-277; past waking imagination taken
  for external reality, 277-280; recollection of prenatal ancestral
  experience, 280, 281; filling up gaps in recollection, 281-283.
  _Illusions connected with, Personal Identity_:--Illusions of Memory and
  Sense of identity, 283, 284; idea of permanent self, how built up,
  285-287; disturbances of sense of identity, 287-290; fallibility and
  trustworthiness of Memory, 290-292.

  NOTE.--Momentary Illusions of Self-consciousness, 293.



  Belief as Immediate or Intuitive, 294-296; simple and compound
  Belief, 296.

  A. _Simple Illusory Belief_:--

      (1) Expectation: its nature, 297, 298; Is Expectation ever intuitive?
        298; Expectation and Inference from the past, 299-301; Expectation
        of new kinds of experience, 301, 302; Permanent Expectations
        of remote events, 302; misrepresentation of future duration,
        302-305; Imaginative transformation of future, 305-307.

      (2) Quasi-Expectations: anticipation of extra-personal experiences,
        307, 308; Retrospective Beliefs, 308-312.

  B. _Compound Illusory Belief_:--

      (1) Representations of permanent things: their structure, 312; our
        representations of others as illusory, 312-315; our representation
        of ourselves as illusory, 315; Illusion of self-esteem, 316-318;
        genesis of illusory opinion of self, 318-322; Illusion in our
        representations of classes of things, 322, 323; and in our views
        of the world as a whole, 323, 324; tendency of belief towards
        divergence, 325; and towards convergence, 326, 327.



  Range of Illusion, 328-330; nature and causes of Illusion in general,
    331-334; Illusion identical with Fallacy, 334; Illusion as abnormal,
    336, 337; question of common error, 337-339; evolutionist's conception
    of error as maladaptation, 339-344; common intuitions
    tested only by philosophy, 344; assumptions of science respecting
    external reality, etc., 344-346; philosophic investigation of these
    assumptions, 346-348; connection between scientific and philosophic
    consideration of Illusion, 348-350; correction of Illusion and its
    implications, 351, 352; Fundamental Intuitions and modern psychology,
    352; psychology as positive science and as philosophy, 353-355;
    points of resemblance between acknowledged Illusions and Fundamental
    Intuitions, 355, 356; question of origin, and question of
    validity, 356, 357; attitude of scientific mind towards philosophic
    scepticism, 357-360; Persistent Intuitions must be taken as true,
    360, 361.




Common sense, knowing nothing of fine distinctions, is wont to draw a
sharp line between the region of illusion and that of sane intelligence.
To be the victim of an illusion is, in the popular judgment, to be
excluded from the category of rational men. The term at once calls up
images of stunted figures with ill-developed brains, half-witted
creatures, hardly distinguishable from the admittedly insane. And this
way of thinking of illusion and its subjects is strengthened by one of
the characteristic sentiments of our age. The nineteenth century
intelligence plumes itself on having got at the bottom of mediæval
visions and church miracles, and it is wont to commiserate the feeble
minds that are still subject to these self-deceptions.

According to this view, illusion is something essentially abnormal and
allied to insanity. And it would seem to follow that its nature and
origin can be best studied by those whose speciality it is to observe
the phenomena of abnormal life. Scientific procedure has in the main
conformed to this distinction of common sense. The phenomena of illusion
have ordinarily been investigated by alienists, that is to say,
physicians who are brought face to face with their most striking forms
in the mentally deranged.

While there are very good reasons for this treatment of illusion as a
branch of mental pathology, it is by no means certain that it can be a
complete and exhaustive one. Notwithstanding the flattering supposition
of common sense, that illusion is essentially an incident in abnormal
life, the careful observer knows well enough that the case is far

There is, indeed, a view of our race diametrically opposed to the
flattering opinion referred to above, namely, the humiliating judgment
that all men habitually err, or that illusion is to be regarded as the
natural condition of mortals. This idea has found expression, not only
in the cynical exclamation of the misanthropist that most men are fools,
but also in the cry of despair that sometimes breaks from the weary
searcher after absolute truth, and from the poet when impressed with the
unreality of his early ideals.

Without adopting this very disparaging opinion of the intellectual
condition of mankind, we must recognize the fact that most men are
sometimes liable to illusion. Hardly anybody is always consistently
sober and rational in his perceptions and beliefs. A momentary fatigue
of the nerves, a little mental excitement, a relaxation of the effort of
attention by which we continually take our bearings with respect to the
real world about us, will produce just the same kind of confusion of
reality and phantasm, which we observe in the insane. To give but an
example: the play of fancy which leads to a detection of animal and
other forms in clouds, is known to be an occupation of the insane, and
is rightly made use of by Shakespeare as a mark of incipient mental
aberration in Hamlet; and yet this very same occupation is quite natural
to children, and to imaginative adults when they choose to throw the
reins on the neck of their phantasy. Our luminous circle of rational
perception is surrounded by a misty penumbra of illusion. Common sense
itself may be said to admit this, since the greatest stickler for the
enlightenment of our age will be found in practice to accuse most of his
acquaintance at some time or another of falling into illusion.

If illusion thus has its roots in ordinary mental life, the study of it
would seem to belong to the physiology as much as to the pathology of
mind. We may even go further, and say that in the analysis and
explanation of illusion the psychologist may be expected to do more than
the physician. If, on the one hand, the latter has the great privilege
of observing the phenomena in their highest intensity, on the other
hand, the former has the advantage of being familiar with the normal
intellectual process which all illusion simulates or caricatures. To
this it must be added that the physician is naturally disposed to look
at illusion mainly, if not exclusively, on its practical side, that is,
as a concomitant and symptom of cerebral disease, which it is needful to
be able to recognize. The psychologist has a different interest in the
subject, being specially concerned to understand the mental antecedents
of illusion and its relation to accurate perception and belief. It is
pretty evident, indeed, that the phenomena of illusion form a region
common to the psychologist and the mental pathologist, and that the
complete elucidation of the subject will need the co-operation of the
two classes of investigator.

In the present volume an attempt will be made to work out the
psychological side of the subject; that is to say, illusions will be
viewed in their relation to the process of just and accurate perception.
In the carrying out of this plan our principal attention will be given
to the manifestations of the illusory impulse in normal life. At the
same time, though no special acquaintance with the pathology of the
subject will be laid claim to, frequent references will be made to the
illusions of the insane. Indeed, it will be found that the two groups of
phenomena--the illusions of the normal and of the abnormal
condition--are so similar, and pass into one another by such insensible
gradations, that it is impossible to discuss the one apart from the
other. The view of illusion which will be adopted in this work is that
it constitutes a kind of border-land between perfectly sane and vigorous
mental life and dementia.

And here at once there forces itself on our attention the question, What
exactly is to be understood by the term "illusion"? In scientific works
treating of the pathology of the subject, the word is confined to what
are specially known as illusions of the senses, that is to say, to false
or illusory perceptions. And there is very good reason for this
limitation, since such illusions of the senses are the most palpable
and striking symptoms of mental disease. In addition to this, it must be
allowed that, to the ordinary reader, the term first of all calls up
this same idea of a deception of the senses.

At the same time, popular usage has long since extended the term so as
to include under it errors which do not counterfeit actual perceptions.
We commonly speak of a man being under an illusion respecting himself
when he has a ridiculously exaggerated view of his own importance, and
in a similar way of a person being in a state of illusion with respect
to the past when, through frailty of memory, he pictures it quite
otherwise than it is certainly known to have been.

It will be found, I think, that there is a very good reason for this
popular extension of the term. The errors just alluded to have this in
common with illusions of sense, that they simulate the form of immediate
or self-evident cognition. An idea held respecting ourselves or
respecting our past history does not depend on any other piece of
knowledge; in other words, is not adopted as the result of a process of
reasoning. What I believe with reference to my past history, so far as I
can myself recall it, I believe instantaneously and immediately, without
the intervention of any premise or reason. Similarly, our notions of
ourselves are, for the most part, obtained apart from any process of
inference. The view which a man takes of his own character or claims on
society he is popularly supposed to receive intuitively by a mere act of
internal observation. Such beliefs may not, indeed, have all the
overpowering force which belongs to illusory perceptions, for the
intuition of something by the senses is commonly looked on as the most
immediate and irresistible kind of knowledge. Still, they must be said
to come very near illusions of sense in the degree of their self-evident

Taking this view of illusion, we may provisionally define it as any
species of error which counterfeits the form of immediate, self-evident,
or intuitive knowledge, whether as sense-perception or otherwise.
Whenever a thing is believed on its own evidence and not as a conclusion
from something else, and the thing then believed is demonstrably wrong,
there is an illusion. The term would thus appear to cover all varieties
of error which are not recognized as fallacies or false inferences. If
for the present we roughly divide all our knowledge into the two regions
of primary or intuitive, and secondary or inferential knowledge, we see
that illusion is false or spurious knowledge of the first kind, fallacy
false or spurious knowledge of the second kind. At the same time, it is
to be remembered that this division is only a very rough one. As will
appear in the course of our investigation, the same error may be called
either a fallacy or an illusion, according as we are thinking of its
original mode of production or of the form which it finally assumes; and
a thorough-going psychological analysis of error may discover that these
two classes are at bottom very similar.

As we proceed, we shall, I think, find an ample justification for our
definition. We shall see that such illusions as those respecting
ourselves or the past arise by very much the same mental processes as
those which are discoverable in the production of illusory perceptions;
and thus a complete psychology of the one class will, at the same time,
contain the explanation of the other classes.

The reader is doubtless aware that philosophers have still further
extended the idea of illusion by seeking to bring under it beliefs which
the common sense of mankind has always adopted and never begun to
suspect. Thus, according to the idealist, the popular notion (the
existence of which Berkeley, however, denied) of an external world,
existing in itself and in no wise dependent on our perceptions of it,
resolves itself into a grand illusion of sense.

At the close of our study of illusions we shall return to this point. We
shall there inquire into the connection between those illusions which
are popularly recognized as such, and those which first come into view
or appear to do so (for we must not yet assume that there are such)
after a certain kind of philosophic reflection. And some attempt will be
made to determine roughly how far the process of dissolving these
substantial beliefs of mankind into airy phantasms may venture to go.

For the present, however, these so-called illusions in philosophy will
be ignored. It is plain that illusion exists only in antithesis to real
knowledge. This last must be assumed as something above all question.
And a rough and provisional, though for our purpose sufficiently
accurate, demarcation of the regions of the real and the illusory seems
to coincide with the line which common sense draws between what all
normal men agree in holding and what the individual holds, whether
temporarily or permanently, in contradiction to this. For our present
purpose the real is that which is true for all. Thus, though physical
science may tell us that there is nothing corresponding to our
sensations of colour in the world of matter and motion which it
conceives as surrounding us; yet, inasmuch as to all men endowed with
the normal colour-sense the same material objects appear to have the
same colour, we may speak of any such perception as practically true,
marking it off from those plainly illusory perceptions which are due to
some subjective cause, as, for example, fatigue of the retina.

To sum up: in treating of illusions we shall assume, what science as
distinguished from philosophy is bound to assume, namely, that human
experience is consistent; that men's perceptions and beliefs fall into a
consensus. From this point of view illusion is seen to arise through
some exceptional feature in the situation or condition of the
individual, which, for the time, breaks the chain of intellectual
solidarity which under ordinary circumstances binds the single member to
the collective body. Whether the common experience which men thus obtain
is rightly interpreted is a question which does not concern us here. For
our present purpose, which is the determination and explanation of
illusion as popularly understood, it is sufficient that there is this
general consensus of belief, and this may provisionally be regarded as
at least practically true.



If illusion is the simulation of immediate knowledge, the most obvious
mode of classifying illusions would appear to be according to the
variety of the knowledge which they simulate.

Now, the popular psychology that floats about in the ordinary forms of
language has long since distinguished certain kinds of unreasoned or
uninferred knowledge. Of these the two best known are perception and
memory. When I see an object before me, or when I recall an event in my
past experience, I am supposed to grasp a piece of knowledge directly,
to know something immediately, and not through the medium of something
else. Yet I know differently in the two cases. In the first I know by
what is called a presentative process, namely, that of sense-perception;
in the second I know by a representative process, namely, that of
reproduction, or on the evidence of memory. In the one case the object
of cognition is present to my perceptive faculties; in the other it is
recalled by the power of memory.

Scientific psychology tends, no doubt, to break down some of these
popular distinctions. Just as the zoologist sometimes groups together
varieties of animals which the unscientific eye would never think of
connecting, so the psychologist may analyze mental operations which
appear widely dissimilar to the popular mind, and reduce them to one
fundamental process. Thus recent psychology draws no sharp distinction
between perception and recollection. It finds in both very much the same
elements, though combined in a different way. Strictly speaking, indeed,
perception must be defined as a presentative-representative operation.
To the psychologist it comes to very much the same thing whether, for
example, on a visit to Switzerland, our minds are occupied in
_perceiving_ the distance of a mountain or in _remembering_ some
pleasant excursion which we made to it on a former visit. In both cases
there is a reinstatement of the past, a reproduction of earlier
experience, a process of adding to a present impression a product of
imagination--taking this word in its widest sense. In both cases the
same laws of reproduction or association are illustrated.

Just as a deep and exhaustive analysis of the intellectual operations
thus tends to identify their various forms as they are distinguished by
the popular mind, so a thorough investigation of the flaws in these
operations, that is to say, the counterfeits of knowledge, will probably
lead to an identification of the essential mental process which
underlies them. It is apparent, for example, that, whether a man
_projects_ some figment of his imagination into the external world,
giving it, present material reality, or whether (if I may be allowed the
term) he _retrojects_ it into the dim region of the past, and takes it
for a reality that has been he is committing substantially the same
blunder. The source of the illusion in both cases is one and the same.

It might seem to follow from this that a scientific discussion of the
subject would overlook the obvious distinction between illusions of
perception and those of memory; that it would attend simply to
differences in the mode of origination of the illusion, whatever its
external form. Our next step, then, would appear to be to determine
these differences in the mode of production.

That there are differences in the origin and source of illusion is a
fact which has been fully recognized by those writers who have made a
special study of sense-illusions. By these the term illusion is commonly
employed in a narrow, technical sense, and opposed to hallucination. An
illusion, it is said, must always have its starting-point in some actual
impression, whereas a hallucination has no such basis. Thus it is an
illusion when a man, under the action of terror, takes a stump of a
tree, whitened by the moon's rays, for a ghost. It is a hallucination
when an imaginative person so vividly pictures to himself the form of
some absent friend that, for the moment, he fancies himself actually
beholding him. Illusion is thus a partial displacement of external fact
by a fiction of the imagination, while hallucination is a total

This distinction, which has been adopted by the majority of recent
alienists[1], is a valuable one, and must not be lost sight of here. It
would seem, from a psychological point of view, to be an important
circumstance in the genesis of a false perception whether the
intellectual process sets out from within or from without. And it will
be found, moreover, that this distinction may be applied to all the
varieties of error which I propose to consider. Thus, for example, it
will be seen further on that a false recollection may set out either
from the idea of some actual past occurrence or from a present product
of the imagination.

It is to be observed, however, that the line of separation between
illusion and hallucination, as thus defined, is a very narrow one. In by
far the largest number of hallucinations it is impossible to prove that
there is no modicum of external agency co-operating in the production of
the effect. It is presumable, indeed, that many, if not all,
hallucinations have such a basis of fact. Thus, the madman who projects
his internal thoughts outwards in the shape of external voices may, for
aught we know, be prompted to do so in part by faint impressions coming
from the ear, the result of those slight stimulations to which the organ
is always exposed, even in profound silence, and which in his case
assume an exaggerated intensity. And even if it is clearly made out that
there are hallucinations in the strict sense, that is to say, false
perceptions which are wholly due to internal causes, it must be conceded
that illusion shades off into hallucination by steps which it is
impossible for science to mark. In many cases it must be left an open
question whether the error is to be classed as an illusion or as a

For these reasons, I think it best not to make the distinction between
illusion and hallucination the leading principle of my classification.
However important psychologically, it does not lend itself to this
purpose. The distinction must be kept in view and illustrated as far as
possible. Accordingly, while in general following popular usage and
employing the term illusion as the generic name, I shall, when
convenient, recognize the narrow and technical sense of the term as
answering to a species co-ordinate with hallucination.

Departing, then, from what might seem the ideally best order of
exposition, I propose, after all, to set out with the simple popular
scheme of faculties already referred to. Even if they are,
psychologically considered, identical operations, perception and memory
are in general sufficiently marked off by a speciality in the form of
the operation. Thus, while memory is the reproduction of something with
a special reference of consciousness to its past existence, perception
is the reproduction of something with a special reference to its present
existence as a part of the presented object. In other words, though
largely _representative_ when viewed as to its origin, perception is
_presentative_ in relation to the object which is supposed to be
immediately present to the mind at the moment.[3] Hence the convenience
of recognizing the popular classification, and of making it our
starting-point in the present case.

All knowledge which has any appearance of being directly reached,
immediate, or self-evident, that is to say, of not being inferred from
other knowledge, may be divided into four principal varieties: Internal
Perception or Introspection of the mind's own feelings;
External Perception; Memory; and Belief, in so far as it simulates the
form of direct knowledge. The first is illustrated in a man's
consciousness of a present feeling of pain or pleasure. The second and
the third kinds have already been spoken of, and are too familiar to
require illustration. It is only needful to remark here that, under
perception, or rather in close conjunction with it, I purpose dealing
with the knowledge of other's feelings, in so far as this assumes the
aspect of immediate knowledge. The term belief is here used to include
expectations and any other kinds of conviction that do not fall under
one of the other heads. An instance of a seemingly immediate belief
would be a prophetic prevision of a coming disaster, or a man's
unreasoned persuasion as to his own powers of performing a difficult

It is, indeed, said by many thinkers that there are no legitimate
immediate beliefs; that all our expectations and other convictions about
things, in so far as they are sound, must repose on other genuinely
immediate knowledge, more particularly sense-perception and memory.
This difficult question need not be discussed here. It is allowed by all
that there is a multitude of beliefs which we hold tenaciously and on
which we are ready to act, which, to the mature mind, wear the
appearance of intuitive truths, owing their cogency to nothing beyond
themselves. A man's belief in his own merits, however it may have been
first obtained, is as immediately assured to him as his recognition of a
real object in the act of sense-perception. It may be added that many of
our every-day working beliefs about the world in which we live, though
presumably derived from memory and perception, tend to lose all traces
of their origin, and to simulate the aspect of intuitions. Thus the
proposition that logicians are in the habit of pressing on our
attention, that "Men are mortal," seems, on the face of it, to common
sense to be something very like a self-evident truth, not depending on
any particular facts of experience.

In calling these four forms of cognition immediate, I must not, however,
be supposed to be placing them on the same logical level. It is plain,
indeed, to a reflective mind that, though each may be called immediate
in this superficial sense, there are perceptible differences in the
degree of their immediacy. Thus it is manifest, after a moment's
reflection, that expectation, so far as it is just, is not primarily
immediate in the sense in which purely presentative knowledge is so,
since it can be shown to follow from something else. So a general
proposition, though through familiarity and innumerable illustrations it
has acquired a self-evident character, is seen with a very little
inspection to be less fundamentally and essentially so than the
proposition, "I am now feeling pain;" and it will be found that even
with respect to memory, when the remembered event is at all remote, the
process of cognition approximates to a mediate operation, namely, one of
inference. What the relative values of these different kinds of
immediate knowledge are is a point which will have to be touched on at
the end of our study. Here it must suffice to warn the reader against
the supposition that this value is assumed to be identical.

It might seem at a first glance to follow from this four-fold scheme of
immediate or quasi-immediate knowledge that there are four varieties of
illusion. And this is true in the sense that these four heads cover all
the main varieties of illusion. If there are only four varieties of
knowledge which can lay any claim to be considered immediate, it must be
that every illusion will simulate the form of one of these varieties,
and so be referable to the corresponding division.

But though there are conceivably these four species of illusion, it does
not follow that there are any actual instances of each class
forthcoming. This we cannot determine till we have investigated the
nature and origin of illusory error. For example, it might be found that
introspection, or the immediate inspection of our own feelings or mental
states, does not supply the conditions necessary to the production of
such error. And, indeed, it is probable that most persons, antecedently
to inquiry, would be disposed to say that to fall into error in the
observation of what is actually going on in our own minds is

With the exception of this first division, however, this scheme may
easily be seen to answer to actual phenomena. That there are illusions
of perception is obvious, since it is to the errors of sense that the
term illusion has most frequently been confined. It is hardly less
evident that there are illusions of memory. The peculiar difficulty of
distinguishing between a past real event and a mere phantom of the
imagination, illustrated in the exclamation, "I either saw it or dreamt
it," sufficiently shows that memory is liable to be imposed on. Finally,
it is agreed on by all that the beliefs we are wont to regard as
self-evident are sometimes erroneous. When, for example, an imaginative
woman says she knows, by mere intuition, that something interesting is
going to happen, say the arrival of a favourite friend, she is plainly
running the risk of being self-deluded. So, too, a man's estimate of
himself, however valid for him, may turn out to be flagrantly false.

In the following discussion of the subject I shall depart from the above
order in so far as to set out with illusions of sense-perception. These
are well ascertained, forming, indeed, the best-marked variety. And the
explanation of these has been carried much further than that of the
others. Hence, according to the rule to proceed from the known to the
unknown, there will be an obvious convenience in examining these first
of all. After having done this, we shall be in a position to inquire
whether there is anything analogous in the region of introspection or
internal perception. Our study of the errors of sense-perception will,
moreover, prove the best preparation for an inquiry into the nature and
mode of production of the remaining two varieties.[4]

I would add that, in close connection with the first division, illusions
of perception, I shall treat the subtle and complicated phenomena of
dreams. Although containing elements which ought, according to
strictness, to be brought under one of the other heads, they are, as
their common appellation, "visions," shows, largely simulations of
external, and more especially visual, perception.

Dreams are no doubt sharply marked off from illusions of
sense-perception by a number of special circumstances. Indeed, it may be
thought that they cannot be adequately treated in a work that aims
primarily at investigating the illusions of normal life, and should
rather be left to those who make the pathological side of the subject
their special study. Yet it may, perhaps, be said that in a wide sense
dreams are a feature of normal life. And, however this be, they have
quite enough in common with other illusions of perception to justify us
in dealing with them in close connection with these.



The errors with which we shall be concerned in this chapter are those
which are commonly denoted by the term illusion, that is to say, those
of sense. They are sometimes called deceptions of the senses; but this
is a somewhat loose expression, suggesting that we can be deceived as to
sensation itself, though, as we shall see later on, this is only true in
a very restricted meaning of the phrase. To speak correctly,
sense-illusions must be said to arise by a simulation of the form of
just and accurate perceptions. Accordingly, we shall most frequently
speak of them as illusions of perception.

In order to investigate the nature of any kind of error, it is needful
to understand the kind of knowledge it imitates, and so we must begin
our inquiry into the nature of illusions of sense by a brief account of
the psychology of perception; and, in doing this, we shall proceed best
by regarding this operation in its most complete form, namely, that of
visual perception.

I may observe that in this analysis of perception I shall endeavour to
keep to known facts, namely, the psychical phenomena or events which
can be seen by the methods of scientific psychology to enter into the
mental content called the percept. I do not now inquire whether such an
analysis can help us to understand all that is meant by perception. This
point will have to be touched later on. Here it is enough to say that,
whatever our philosophy of perception may be, we must accept the
psychological fact that the concrete mental state in the act of
perception is built up out of elements, the history of which can be
traced by the methods of mental science.

_Psychology of Perception._

Confining ourselves for the present to the mental, as distinguished from
the physical, side of the operation, we soon find that perception is not
so simple a matter as it might at first seem to be. When a man on a hot
day looks at a running stream and "sees" the delicious coolness, it is
not difficult to show that he is really performing an act of mental
synthesis, or imaginative construction. To the sense-impression[5] which
his eye now gives him, he adds something which past experience has
bequeathed to his mind. In perception, the material of sensation is
acted on by the mind, which embodies in its present attitude all the
results of its past growth. Let us look at this process of synthesis a
little more closely.

When a sensation arises in the mind, it may, under certain
circumstances, go unattended to. In that case there is no perception.
The sensation floats in the dim outer regions of consciousness as a
vague feeling, the real nature and history of which are unknown. This
remark applies not only to the undefined bodily sensations that are
always oscillating about the threshold of obscure consciousness, but to
the higher sensations connected with the special organs of perception.
The student in optics soon makes the startling discovery that his field
of vision has all through his life been haunted with weird shapes which
have never troubled the serenity of his mind just because they have
never been distinctly attended to.

The immediate result of this process of directing the keen glance of
attention to a sensation is to give it greater force and distinctness.
By attending to it we discriminate it from other feelings present and
past, and classify it with like sensations previously received. Thus, if
I receive a visual impression of the colour orange, the first
consequence of attending to it is to mark it off from other
colour-impressions, including those of red and yellow. And in
recognizing the peculiar quality of the impression by applying to it the
term orange, I obviously connect it with other similar sensations called
by the same name. If a sensation is perfectly new, there cannot, of
course, be this process of classifying, and in this case the closely
related operation of discriminating it from other sensations is less
exactly performed. But it is hardly necessary to remark that, in the
mind of the adult, under ordinary circumstances, no perfectly new
sensation ever occurs.

When the sensation, or complex sensation, is thus defined and
recognized, there follows the process of interpretation, by which I mean
the taking up of the impression as an element into the complex mental
state known as a percept. Without going into the philosophical question
of what this process of synthesis exactly means, I may observe that, by
common consent, it takes place to a large extent by help of a
reproduction of sensations of various kinds experienced in the past.
That is to say, the details in this act of combination are drawn from
the store of mental recollections to which the growing mind is ever
adding. In other words, the percept arises through a fusion of an actual
sensation with mental representations or "images" of sensation.[6] Every
element of the object that we thus take up in the act of perception, or
put into the percept, as its actual size, distance, and so on, will be
found to make itself known to us through mental images or revivals of
past experiences, such as those we have in handling the object, moving
to and from it, etc. It follows that if this is an essential ingredient
in the act of perception, the process closely resembles an act of
inference; and, indeed, Helmholtz distinctly calls the perception of
distance an unconscious inference or a mechanically performed act of

I have hinted that these recovered sensations include the feelings we
experience in connection with muscular activity, as in moving our limbs,
resisting or lifting heavy bodies, and walking to a distant object.
Modern psychology refers the eye's instantaneous recognition of the most
important elements of an object (its essential or "primary" qualities)
to a reinstatement of such simple experiences as these. It is, indeed,
these reproductions which are supposed to constitute the substantial
background of our percepts.

Another thing worth noting with respect to this process of filling up a
sense-impression is that it draws on past sensations of the eye itself.
Thus, when I look at the figure of an acquaintance from behind, my
reproductive visual imagination supplies a representation of the
impressions I am wont to receive when the more interesting aspect of the
object, the front view, is present to my visual sense.[7]

We may distinguish between different steps in the full act of visual
recognition. First of all comes the construction of a material object of
a particular figure and size, and at a particular distance; that is to
say, the recognition of a tangible thing having certain simple
space-properties, and holding a certain relation to other objects, and
more especially our own body, in space. This is the bare perception of
an object, which always takes place even in the case of perfectly new
objects, provided they are seen with any degree of distinctness. It is
to be added that the reference of a sensation of light or colour to such
an object involves the inclusion of a quality answering to the
sensation, as brightness, or blue colour, in the thing thus intuited.

This part of the process of filling in, which is the most instantaneous,
automatic, and unconscious, may be supposed to answer to the most
constant and therefore the most deeply organized connections of
experience; for, speaking generally, we never have an impression of
colour, except when there are circumstances present which are fitted to
yield us those simple muscular and tactual experiences through which the
ideas of a particular form, size, etc., are pretty certainly obtained.

The second step in this process of presentative construction is the
recognition of an object as one of a class of things, for example,
oranges, having certain special qualities, as a particular taste. In
this step the connections of experience are less deeply organized, and
so we are able to some extent, by reflection, to recognize it as a kind
of intellectual working up of the materials supplied us by the past. It
is to be noted that this process of recognition involves a compound
operation of classifying impressions as distinguished from that simple
operation by which a single impression, such as a particular colour, is
known. Thus the recognition of such an object as an orange takes place
by a rapid classing of a multitude of passive sensations of colour,
light, and shade, and those active or muscular sensations which are
supposed to enter into the visual perception of form.

A still less automatic step in the process of visual recognition is that
of identifying individual objects, as Westminster Abbey, or a friend,
John Smith. The amount of experience that is here reproduced may be very
large, as in the case of recognizing a person with whom we have had a
long and intimate acquaintance.

If the recognition of an object as one of a class, for example, an
orange, involves a compound process of classing impressions, that of an
individual object involves a still more complicated process. The
identification of a friend, simple as this operation may at first
appear, really takes place by a rapid classing of all the salient
characteristic features which serve as the visible marks of that
particular person.

It is to be noted that each kind of recognition, specific and
individual, takes place by a consciousness of likeness amid unlikeness.
It is obvious that a new individual object has characters not shared in
by other objects previously inspected. Thus, we at once class a man with
a dark-brown skin, wearing a particular garb, as a Hindoo, though he may
differ in a host of particulars from the other Hindoos that we have
observed. In thus instantly recognizing him as a Hindoo, we must, it is
plain, attend to the points of similarity, and overlook for the instant
the points of dissimilarity. In the case of individual identification,
the same thing happens. Strictly speaking, no object ever appears
exactly the same to us on two occasions. Apart from changes in the
object itself, especially in the case of living beings, there are
varying effects of illumination, of position in relation to the eye, of
distance, and so on, which very distinctly affect the visual impression
at different times. Yet the fact of our instantly recognizing a familiar
object in spite of these fluctuations of appearance, proves that we are
able to overlook a very considerable amount of diversity when a certain
amount of likeness is present.

It is further to be observed that in these last stages of perception we
approach the boundary line between perception and inference. To
recognize an object as one of a class is often a matter of conscious
reflection and judgment, even when the class is constituted by obvious
material qualities which the senses may be supposed to apprehend
immediately. Still more clearly does perception pass into inference when
the class is constituted by less obvious qualities, which require a
careful and prolonged process of recollection, discrimination, and
comparison, for their recognition. Thus, to recognize a man by certain
marks of gesture and manner as a military man or a Frenchman, though
popularly called a perception, is much more of an unfolded process of
conscious inference. And what applies to specific recognition applies
still more forcibly to individual recognition, which is often a matter
of very delicate conscious comparison and judgment. To say where the
line should be drawn here between perception and observation on the one
hand, and inference on the other, is clearly impossible. Our whole study
of the illusions of perception will serve to show that the one shades
off into the other too gradually to allow of our drawing a hard and fast
line between them.

Finally, it is to be noted that these last stages of perception bring us
near the boundary line which separates objective experience as common
and universal, and subjective or variable experience as confined to one
or to a few. In the bringing of the object under a certain class of
objects there is clearly room for greater variety of individual
perception. For example, the ability to recognize a man as a Frenchman
turns on a special kind of previous experience. And this transition from
the common or universal to the individual experience is seen yet more
plainly in the case of individual recognition. To identify an object,
say a particular person, commonly presupposes some previous experience
or knowledge of this object, and the existence in the past of some
special relation of the recognizer to the recognized, if only that of an
observer. In fact, it is evident that in this mode of recognition we
have the transition from common perception to individual

While we may thus distinguish different steps in the process of visual
recognition, we may make a further distinction, marking off a passive
and an active stage in the process. The one may be called the stage of
preperception, the other that of perception proper.[9] In the first the
mind holds itself in a passive attitude, except in so far as the
energies of external attention are involved. The impression here awakens
the mental images which answer to past experiences according to the
well-known laws of association. The interpretative image which is to
transform the impression into a percept is now being formed by a mere
process of suggestion.

When the image is thus formed, the mind may be said to enter upon a more
active stage, in which it now views the impression through the image, or
applies this as a kind of mould or framework to the impression. This
appears to involve an intensification of the mental image, transforming
it from a representative to a presentative mental state, making it
approximate somewhat to the full intensity of the sensation. In many of
our instantaneous perceptions these two stages are indistinguishable to
consciousness. Thus, in most cases, the recognition of size, distance,
etc., takes place so rapidly that it is impossible to detect the two
phases here separated. But in the classification of an object, or the
identification of an individual thing, there is often an appreciable
interval between the first reception of the impression and the final
stage of complete recognition. And here it is easy to distinguish the
two stages of preperception and perception. The interpretative image is
slowly built up by the operation of suggestion, at the close of which
the impression is suddenly illumined as by a flash of light, and takes a
definite, precise shape.

Now, it is to be noted that the process of preperception will be greatly
aided by any circumstance that facilitates the construction of the
particular interpretative image required. Thus, the more frequently a
similar process of perception has been performed in the past, the more
ready will the mind be to fall into the particular way of interpreting
the impression. As G.H. Lewes well remarks, "The artist sees details
where to other eyes there is a vague or confused mass; the naturalist
sees an animal where the ordinary eye only sees a form." This is but one
illustration of the seemingly universal mental law, that what is
repeatedly done will be done more and more easily.

The process of preperception may be shortened, not only by means of a
_permanent_ disposition to frame the required interpretative scheme, the
residuum of past like processes, but also by means of any _temporary_
disposition pointing in the same direction. If, for example, the mind of
a naturalist has just been occupied about a certain class of bird, that
is to say, if he has been dwelling on the _mental image_ of this bird,
he will recognize one at a distance more quickly than he would otherwise
have done. Such a simple mental operation as the recognition of one of
the less common flowers, say a particular orchid, will vary in duration
according as we have or have not been recently forming an image of this
flower. The obvious explanation of this is that the mental image of an
object bears a very close resemblance to the corresponding percept,
differing from it, indeed, in degree only, that is to say, through the
fact that it involves no actual sensation. Here again we see illustrated
a general psychological law, namely, that what the mind has recently
done, it tends (within certain limits) to go on doing.

It is to be noticed, further, that the perception of a single object or
event is rarely an isolated act of the mind. We recognize and understand
the things that surround us through their relations one to another.
Sometimes the adjacent circumstances and events suggest a definite
expectation of the new impression. Thus, for example, the sound of a gun
heard during a walk in the country is instantly interpreted by help of
suggestions due to the previous appearance of the sportsman, and the act
of raising the gun to his shoulder. It may be added that the verbal
suggestions of others act very much like the suggestions of external
circumstances. If I am told that a gun is going to be fired, my mind is
prepared for it just as though I saw the sportsman.[10]

More frequently the effect of such surrounding circumstances is to give
an air of familiarity to the new impression, to shorten the interval in
which the required interpretative image is forthcoming. Thus, when
travelling in Italy, the visual impression answering to a ruined temple
or a bareheaded friar is construed much more rapidly than it would be
elsewhere, because of the attitude of mind due to the surrounding
circumstances. In all such cases the process of preperception connected
with a given impression is effected more or less completely by the
suggestions of other and related impressions.

It follows from all that has been just said that our minds are never in
exactly the same state of readiness with respect to a particular process
of perceptional interpretation. Sometimes the meaning of an impression
flashes on us at once, and the stage of preperception becomes
evanescent. At other times the same impression will fail for an
appreciable interval to divulge its meaning. These differences are, no
doubt, due in part to variations in the state of attention at the
moment; but they depend as well on fluctuations in the degree of the
mind's readiness to look at the impression in the required way.

In order to complete this slight analysis of perception, we must look
for a moment at its physical side, that is to say, at the nervous
actions which are known or supposed with some degree of probability to
accompany it.

The production of the sensation is known to depend on a certain external
process, namely, the action of some stimulus, as light, on the
sense-organ, which stimulus has its point of departure in the object,
such as it is conceived by physical science. The sensation arises when
the nervous process is transmitted through the nerves to the conscious
centre, often spoken of as the sensorium, the exact seat of which is
still a matter of some debate.

The intensification of the sensation by the reaction of attention is
supposed to depend on some reinforcement of the nervous excitation in
the sensory centre proceeding from the motor regions, which are
hypothetically regarded as the centre of attention.[11] The
classification of the impression, again, is pretty certainly correlated
with the physical fact that the central excitation calls into activity
elements which have already been excited in the same way.

The nervous counterpart of the final stage of perception, the synthesis
of the sensation and the mental representation, is not clearly
ascertained. A sensation clearly resembles a mental image in quality. It
is most obviously marked off from the image by its greater vividness or
intensity. Agreeably to this view, it is now held by a number of eminent
physiologists and psychologists that the nervous process underlying a
sensation occupies the same central region as that which underlies the
corresponding image. According to this theory, the two processes differ
in their degree of energy only, this difference being connected with the
fact that the former involves, while the latter does not involve, the
peripheral region of the nervous system. Accepting this view as on the
whole well founded, I shall speak of an ideational, or rather an
imaginational; and a sensational nervous process, and not of an
ideational and a sensational centre.[12]

The special force that belongs to the representative element in a
percept, as compared with that of a pure "perceptional" image,[13] is
probably connected with the fact that, in the case of actual perception,
the nervous process underlying the act of imaginative construction is
organically united to the initial sensational process, of which indeed
it may be regarded as a continuation.

For the physical counterpart of the two stages in the interpretative
part of perception, distinguished as the passive stage of preperception,
and the active stage of perception proper, we may, in the absence of
certain knowledge, fall back on the hypothesis put forward by Dr. J.
Hughlings Jackson, in the articles in _Brain_ already referred to,
namely, that the former answers to an action of the right hemisphere of
the brain, the latter to a subsequent action of the left hemisphere. The
expediting of the process of preperception in those cases where it has
frequently been performed before, is clearly an illustration of the
organic law that every function is improved by exercise. And the
temporary disposition to perform the process due to recent imaginative
activity, is explained at once on the physical side by the supposition
that an actual perception and a perceptional image involve the activity
of the same nervous tracts. For, assuming this to be the case, it
follows, from a well-known organic law, that a recent excitation would
leave a temporary disposition in these particular structures to resume
that particular mode of activity.

What has here been said about visual perception will apply, _mutatis
mutandis_, to other kinds. Although the eye is the organ of perception
_par excellence_, our other senses are also avenues by which we intuit
and recognize objects. Thus touch, especially when it is finely
developed as it is in the blind, gives an immediate knowledge of
objects--a more immediate knowledge, indeed, of their fundamental
properties than sight. What makes the eye so vastly superior to the
organ of touch as an instrument of perception, is first of all the range
of its action, taking in simultaneously a large number of impressions
from objects at a distance as well as near; and secondly, though this
may seem paradoxical, the fact that it gives us so much indirectly, that
is, by way of association and suggestion. This is the interesting side
of visual perception, that, owing to the vast complex of distinguishable
sensations of light and colour of various qualities and intensities,
together with the muscular sensations attending the varying positions of
the organ, the eye is able to recognize at any instant a whole external
world with its fundamental properties and relations. The ear comes next
to the eye in this respect, but only after a long interval, since its
sensations (even in the case of musical combinations) do not
simultaneously order themselves in an indefinitely large group of
distinguishable elements, and since even the comparatively few
sensations which it is capable of simultaneously receiving,
being altogether passive--that is to say, having no muscular
accompaniments--impart but little and vague information respecting the
external order. It is plain, then, that in the study of illusion, where
the indirectly known elements are the thing to be considered, the eye,
and after this the ear, will mostly engage our attention.[14]

So much it seemed needful to say about the mechanism of perception, in
order to understand the slight disturbances of this mechanism that
manifest themselves in sense-illusion. It may be added that our study of
these illusions will help still further to elucidate the exact nature of
perception. Normal mental life, as a whole, at once illustrates, and is
illustrated by, abnormal. And while we need a rough provisional theory
of accurate perception in order to explain illusory perception at all,
the investigation of this latter cannot fail to verify and even render
more complete the theory which it thus temporarily adopts.

_Illusions of Perception._

With this brief psychological analysis of perception to help us, let us
now pass to the consideration of the errors incident to the process,
with a view to classify them according to their psychological nature and

And here there naturally arises the question, How shall we define an
illusion of perception? When trying to fix the definition of illusion in
general, I practically disposed of this question. Nevertheless, as the
point appears to me to be of some importance, I shall reproduce and
expand one or two of the considerations then brought forward.

It is said by certain, philosophers that perception, as a whole, is an
illusion, inasmuch as it involves the fiction of a real thing
independent of mind, yet somehow present to it in the act of
sense-perception. But this is a question for philosophy, not for
science. Science, including psychology, assumes that in perception there
is something real, without inquiring what it may consist of, or what its
meaning may be. And though in the foregoing analysis of perception,
viewed as a complex mental phenomenon or psychical process, I have
argued that a percept gets its concrete filling up out of elements of
conscious experience or sensations, I have been careful not to contend
that the particular elements of feeling thus represented are the
_object_ of perception or the thing perceived. It may be that what we
mean by a single object with its assemblage of qualities is much more
than any number of such sensations; and it must be confessed that, on
the face of it, it seems to be much more. And however this be, the
question, What is meant by object; and is the common persuasion of the
existence of such an entity in the act of perception accurate or
illusory? must be handed over to philosophy.

While in the following examination of sense-illusions we put out of
sight what certain philosophers say about the illusoriness of perception
as a whole, we shall also do well to leave out of account what physical
science is sometimes supposed to tell us respecting a constant element
of illusion in perception. The physicist, by reducing all external
changes to "modes of motion," appears to leave no room in his
world-mechanism for the secondary qualities of bodies, such as light
and heat, as popularly conceived. Yet, while allowing this, I think we
may still regard the attribution of qualities like colour to objects as
in the main correct and answering to a real fact. When a person says an
object is red, he is understood by everybody as affirming something
which is true or false, something therefore which either involves an
external fact or is illusory. It would involve an external fact whenever
the particular sensation which he receives is the result of a physical
action (other vibrations of a certain order), which would produce a like
sensation in anybody else in the same situation and endowed with the
normal retinal sensibility. On the other hand, an illusory attribution
of colour would imply that there is no corresponding physical agency at
work in the case, but that the sensation is connected with exceptional
individual conditions, as, for example, altered retinal sensibility.

We are now, perhaps, in a position to frame a rough definition of an
illusion of perception as popularly understood. A large number of such
phenomena may be described as consisting in the formation of percepts or
quasi-percepts in the minds of individuals under external circumstances
which would not give rise to similar percepts in the case of other

A little consideration, however, will show that this is not an adequate
definition of what is ordinarily understood by an illusion of sense.
There are special circumstances which are fitted to excite a momentary
illusion in all minds. The optical illusions due to the reflection and
refraction of light are not peculiar to the individual, but arise in all
minds under precisely similar external conditions.

It is plain that the illusoriness of a perception is in these cases
determined in relation to the sense-impressions of other moments and
situations, or to what are presumably better percepts than the present
one. Sometimes this involves an appeal from one sense to another. Thus,
there is the process of verification of sight by touch, for example, in
the case of optical images, a mode of perception which, as we have seen,
gives a more direct cognition of external quality. Conversely, there may
occasionally be a reference from touch to sight, when it is a question
of discriminating two points lying very close to one another. Finally,
the same sense may correct itself, as when the illusion of the
stereoscope is corrected by afterwards looking at the two separate

We may thus roughly define an illusion of perception as consisting in
the formation of a quasi-percept which is peculiar to an individual, or
which is contradicted by another and presumably more accurate percept.
Or, if we take the meaning of the word common to include both the
universal as contrasted with the individual experience, and the
permanent, constant, or average, as distinguished from the momentary and
variable percept, we may still briefly describe an illusion of
perception as a deviation from the common or collective experience.

_Sources of Sense-Illusion._

Understanding sense-illusion in this way, let us glance back at the
process of perception in its several stages or aspects, with the object
of discovering what room occurs for illusion.

It appears at first as if the preliminary stages--the reception,
discrimination, and classification of an impression--would not offer the
slightest opening for error. This part of the mechanism of perception
seems to work so regularly and so smoothly that one can hardly conceive
a fault in the process. Nevertheless, a little consideration will show
that even here all does not go on with unerring precision.

Let us suppose that the very first step is wanting--distinct attention
to an impression. It is easy to see that this will favour illusion by
leading to a confusion of the impression. Thus the timid man will more
readily fall into the illusion of ghost-seeing than a cool-headed
observant man, because he is less attentive to the actual impression of
the moment. This inattention to the sense-impression will be found to be
a great co-operating factor in the production of illusions.

But if the sensation is properly attended to, can there be error through
a misapprehension of what is actually in the mind at the moment? To say
that there can may sound paradoxical, and yet in a sense this is
demonstrable. I do not mean that there is an observant mind behind and
distinct from the sensation, and failing to observe it accurately
through a kind of mental short-sightedness. What I mean is that the
usual psychical effect of the incoming nervous process may to some
extent be counteracted by a powerful reaction of the centres. In the
course of our study of illusions, we shall learn that it is possible for
the quality of an impression, as, for example, of a sensation of colour,
to be appreciably modified when there is a strong tendency to regard it
in one particular way.

Postponing the consideration of these, we may say that certain illusions
appear clearly to take their start from an error in the process of
classifying or identifying a present impression. On the physical side,
we may say that the first stages of the nervous process, the due
excitation of the sensory centre in accordance with the form of the
incoming stimulation and the central reaction involved in the
recognition of the sensation, are incomplete. These are so limited and
comparatively unimportant a class, that it will be well to dispose of
them at once.

_Confusion of the Sense-Impression._

The most interesting case of such an error is where the impression is
unfamiliar and novel in character. I have already remarked that in the
mental life of the adult perfectly new sensations never occur. At the
same time, comparatively novel impressions sometimes arise. Parts of the
sensitive surface of the body which rarely undergo stimulation are
sometimes acted on, and at other times they receive partially new modes
of stimulation. In such cases it is plain that the process of classing
the sensation or recognizing it is not completed. It is found that
whenever this happens there is a tendency to exaggerate the intensity of
the sensation. The very fact of unfamiliarity seems to give to the
sensation a certain exciting character. As something new and strange, it
for the instant slightly agitates and discomposes the mind. Being unable
to classify it with its like, we naturally magnify its intensity, and
so tend to ascribe it to a disproportionately large cause.

For instance, a light bandage worn about the body at a part usually free
from pressure is liable to be conceived as a weighty mass. The odd sense
of a big cavity in the mouth, which we experience just after the loss of
a tooth, is probably another illustration of this principle. And a third
example may also be supplied from the recollection of the dentist's
patient, namely, the absurd imagination which he tends to form as to
what is actually going on in his mouth when a tooth is being bored by a
modern rotating drill. It may be found that the same principle helps to
account for the exaggerated importance which we attach to the
impressions of our dreams.

It is evident that all indistinct impressions are liable to be wrongly
classed. Sensations answering to a given colour or form, are, when
faint, easily confused with other sensations, and so an opening occurs
for illusion. Thus, the impressions received from distant objects are
frequently misinterpreted, and, as we shall see by-and-by, it is in this
region of hazy impression that imagination is wont to play its most
startling pranks.

It is to be observed that the illusions arising from wrong
classification will be more frequent in the case of those senses where
discrimination is low. Thus, it is much easier in a general way to
confuse two sensations of smell than two sensations of colour. Hence the
great source of such errors is to be found in that mass of obscure
sensation which is connected with the organic processes, as digestion,
respiration, etc., together with those varying tactual and motor
feelings, which result from what is called the subjective stimulation of
the tactual nerves, and from changes in the position and condition of
the muscles. Lying commonly in what is known as the sub-conscious region
of mind, undiscriminated, vague, and ill-defined, these sensations, when
they come to be specially attended to, readily get misapprehended, and
so lead to illusion, both in waking life and in sleep. I shall have
occasion to illustrate this later on.

With these sensations, the result of stimulations coming from remote
parts of the organism, may be classed the ocular impressions which we
receive in indirect vision. When the eye is not fixed on an object, the
impression, involving the activity of some-peripheral region of the
retina, is comparatively indistinct. This will be much more the case
when the object lies at a distance for which the eye is not at the time
accommodated. And in these circumstances, when we happen to turn our
attention to the impression, we easily misapprehend it, and so fall into
illusion. Thus, it has been remarked by Sir David Brewster, in his
_Letters on Natural Magic_ (letter vii.), that when looking through a
window at some object beyond, we easily suppose a fly on the window-pane
to be a larger object, as a bird, at a greater distance.[15]

While these cases of a confusion or a wrong classification of the
sensation are pretty well made out, there are other illusions or
quasi-illusions respecting which it is doubtful whether they should be
brought under this head. For example, it was found by Weber, that when
the legs of a pair of compasses are at a certain small distance apart
they will be felt as two by some parts of the tactual surface of the
body, but only as one by other parts. How are we to regard this
discrepancy? Must we say that in the latter case there are two
sensations, only that, being so similar, they are confused one with
another? There seems some reason for so doing, in the fact that, by a
repeated exercise of attention to the experiment, they may afterwards be
recognized as two.

We here come on the puzzling question, How much in the character of the
sensation must be regarded as the necessary result of the particular
mode of nervous stimulation at the moment, together with the laws of
sensibility, and how much must be put down to the reaction of the mind
in the shape of attention and discrimination? For our present purpose we
may say that, whenever a deliberate effort of attention does not suffice
to alter the character of a sensation, this may be pretty safely
regarded as a net result of the nervous process, and any error arising
may be referred to the later stages of the process of perception. Thus,
for example, the taking of the two points of a pair of compasses for
one, where the closest attention does not discover the error, is best
regarded as arising, not from a confusion of the sense-impression, but
from a wrong interpretation of a sensation, occasioned by an
overlooking of the limits of local discriminative sensibility.

_Misinterpretation of the Sense-Impression._

Enough has been said, perhaps, about those errors of perception which
have their root in the initial process of sensation. We may now pass to
the far more important class of illusions which are related to the later
stages of perception, that is to say, the process of interpreting the
sense-impression. Speaking generally, one may describe an illusion of
perception as a misinterpretation. The wrong kind of interpretative
mental image gets combined with the impression, or, if with Helmholtz we
regard perception as a process of "unconscious inference," we may say
that these illusions involve an unconscious fallacious conclusion. Or,
looking at the physical side of the operation, it may be said that the
central course taken by the nervous process does not correspond to the
external relations of the moment.

As soon as we inspect these illusions of interpretation, we see that
they fall into two divisions, according as they are connected with the
process of _suggestion_, that is to say, the formation of the
interpretative image so far as determined by links of association with
the actual impression, or with an independent process of _preperception_
as explained above. Thus, for example, we fall into the illusion of
hearing two voices when our shout is echoed back, just because the
second auditory impression irresistibly calls up the image of a second
shouter. On the other hand, a man experiences the illusion of seeing
spectres of familiar objects just after exciting his imagination over a
ghost-story, because the mind is strongly predisposed to frame this kind
of percept. The first class of illusions arises from without, the
sense-impression being the starting-point, and the process of
preperception being controlled by this. The second class arises rather
from within, from an independent or spontaneous activity of the
imagination. In the one case the mind is comparatively passive; in the
other it is active, energetically reacting on the impression, and
impatiently anticipating the result of the normal process of
preperception. Hence I shall, for brevity's sake, commonly speak of them
as Passive and Active Illusions.[16]

I may, perhaps, illustrate these two classes of illusion by the simile
of an interpreter poring over an old manuscript. The first would be due
to some peculiarity in the document misleading his judgment, the second
to some caprice or preconceived notion in the interpreter's mind.

It is not difficult to define conjecturally the physiological conditions
of these two large classes of illusion. On the physical side, an
illusion of sense, like a just perception, is the result of a fusion of
the nervous process answering to a sensation with a nervous process
answering to a mental image. In the case of passive illusions, this
fusion may be said to take place in consequence of some point of
connection between the two. The existence of such a connection appears
to be involved in the very fact of suggestion, and may be said to be
the organic result of frequent conjunctions of the two parts of the
nervous operation in our past history. In the case of active illusions,
however, which spring rather from the independent energy of a particular
mode of the imagination, this point of organic connection is not the
only or even the main thing. In many cases, as we shall see, there is
only a faint shade of resemblance between the present impression and the
mental image with which it is overlaid. The illusions dependent on
vivid, expectation thus answer much less to an objective conjunction of
past experiences than to a capricious subjective conjunction of mental
images. Here, then, the fusion of nervous processes must have another
cause. And it is not difficult to assign such a cause. The antecedent
activity of imagination doubtless involves as its organic result a
powerful temporary disposition in the nervous structures concerned to go
on acting. In other words, they remain in a state of sub-excitation,
which can be raised to full excitation by a slight additional force. The
more powerful this disposition in the centres involved in the act of
imagination, the less the additional force of external stimulus required
to excite them to full activity.

Considering the first division, passive illusions, a little further, we
shall see that they may be broken up into two sub-classes, according to
the causes of the errors. In a general way we assume that the impression
always answers to some quality of the object which is perceived, and
varies with this; that, for example, our sensation of colour invariably
represents the quality of external colour which we attribute to the
object. Or, to express it physically, we assume that the external force
acting on the sense-organ invariably produces the same effect, and that
the effect always varies with the external cause. But this assumption,
though true in the main, is not perfectly correct. It supposes that the
organic conditions are constant, and that the organic process faithfully
reflects the external operation. Neither of these suppositions is
strictly true. Although in general we may abstract from the organism and
view the relation between the external fact and the mental impression as
direct, we cannot always do so.

This being so, it is possible for errors of perception to arise through
peculiarities of the nervous organization itself. Thus, as I have just
observed, sensibility has its limits, and these limits are the
starting-point in a certain class of widely shared or _common_
illusions. An example of this variety is the taking of the two points of
a pair of compasses for one by the hand, already referred to. Again, the
condition of the nervous structures varies indefinitely, so that one and
the same stimulus may, in the case of two individuals, or of the same
individual at different times, produce widely unlike modes of sensation.
Such variations are clearly fitted to lead to gross _individual_ errors
as to the external cause of the sensation. Of this sort is the illusory
sense of temperature which we often experience through a special state
of the organ employed.

While there are these errors of interpretation due to some peculiarity
of the organization, there are others which involve no such peculiarity,
but arise through the special character or exceptional conformation of
the environment at the moment. Of this order are the illusions connected
with the reflection of light and sound. We may, perhaps, distinguish the
first sub-class as organically conditioned illusions, and the second as
extra-organically determined illusions. It may be added that the latter
are roughly describable as common illusions. They thus answer in a
measure to the first variety of organically conditioned illusions,
namely, those connected with the limits of sensibility. On the other
hand, the active illusions, being essentially individual or subjective,
may be said to correspond to the other variety of this class--those
connected with variations of sensibility.

Our scheme of sense-illusions is now complete. First of all, we shall
take up the passive illusions, beginning with those which are
conditioned by special circumstances in the organism. After that we
shall illustrate those which depend on peculiar circumstances in the
environment. And finally, we shall separately consider what I have
called the active illusions of sense.

It is to be observed that these illusions of perception properly so
called, namely, the errors arising from a wrong interpretation of an
impression, and, not from a confusion of one impression with another are
chiefly illustrated in the region of the two higher senses, sight and
hearing. For it is here, as we have seen, that the interpretative
imagination has most work to do in evolving complete percepts of
material, tangible objects, having certain relations in space, out of a
limited and homogeneous class of sensations, namely, those of light and
colour, and of sound. As I have before observed, tactual perception, in
so far as it is the recognition of an object of a certain size,
hardness, and distance from our body, involves the least degree of
interpretation, and so offers little room for error; it is only when
tactual perception amounts to the _recognition_ of an individual object,
clothed with secondary as well as primary qualities, that an opening for
palpable error occurs.

With respect, however, to the first sub-class of these illusions,
namely, those arising from organic peculiarities which give a twist, so
to speak, to the sensation, no very marked contrast between the
different senses presents itself. So that in illustrating this group we
shall be pretty equally concerned with the various modes of perception
connected with the different senses.

It may be said once for all that in thus marking off from one another
certain groups of illusion, I am not unmindful of the fact that these
divisions answer to no very sharp natural distinctions. In fact, it will
be found that one class gradually passes into the other, and that the
different characteristics here separated often combine in a most
perplexing way. All that is claimed for this classification is that it
is a convenient mode of mapping out the subject.



A. _Passive Illusions (a) as determined by the Organism._

In dealing with the illusions which are related to certain peculiarities
in the nervous organism and the laws of sensibility, I shall commence
with those which are connected with certain limits of sensibility.

_Limits of Sensibility._

To begin with, it is known that the sensation does not always answer to
the external stimulus in its degree or intensity. Thus, a certain amount
of stimulation is necessary before any sensation arises. And this will,
of course, be greater when there is little or no attention directed to
the impression, that is to say, no co-operating central reaction. Thus
it happens that slight stimuli go overlooked, and here illusion may have
its starting-point. The most familiar example of such slight errors is
that of movement. When we are looking at objects, our ocular muscles are
apt to execute very slight movements which escape our notice. Hence we
tend, under certain circumstances, to carry over the retinal result of
the movement, that is to say, the impression produced by a shifting of
the parts of the retinal image to new nervous elements, to the object
itself, and so to transform a "subjective" into an "objective" movement.
In a very interesting work on apparent or illusory movements, Professor
Hoppe has fully investigated the facts of such slight movements, and
endeavoured to specify their causes.[17]

Again, even when the stimulus is sufficient to produce a conscious
impression, the degree of the feeling may not represent the degree of
the stimulus. To take a very inconspicuous case, it is found by Fechner
that a given increase of force in the stimulus produces a less amount of
difference in the resulting sensations when the original stimulus is a
powerful one than when it is a feeble one. It follows from this, that
differences in the degree of our sensations do not exactly correspond to
objective differences. For example, we tend to magnify the differences
of light among objects, all of which are feebly illuminated, that is to
say, to see them much more removed from one another in point of
brightness than when they are more strongly illuminated. Helmholtz
relates that, owing to this tendency, he has occasionally caught
himself, on a dark night, entertaining the illusion that the
comparatively bright objects visible in twilight were self-luminous.[18]

Again, there are limits to the conscious separation of sensations which
are received together, and this fact gives rise to illusion. In general,
the number of distinguishable sensations answers to the number of
external causes; but this is not always the case, and here we naturally
fall into the error of mistaking the number of the stimuli. Reference
has already been made to this fact in connection with the question
whether consciousness can be mistaken as to the character of a present

The case of confusing two impressions when the sensory fibres involved
are very near one another, has already been alluded to. Both in touch
and in sight we always take two or more points for one when they are
only separated by an interval that falls below the limits of local
discrimination. It seems to follow from this that our perception of the
world as a continuum, made up of points perfectly continuous one with
another may, for what we know, be illusory. Supposing the universe to
consist of atoms separated by very fine intervals, then it is
demonstrable that it would appear to our sensibility as a continuum,
just as it does now.[19]

Two or more simultaneous sensations are indistinguishable from one
another, not only when they have nearly the same local origin, but under
other circumstances. The blending of partial sensations of tone in a
_klang_-sensation, and the coalescence in certain cases of the
impressions received by way of the two retinas, are examples of this. It
is not quite certain what determines this fusion of two simultaneous
feelings. It may be said generally that it is favoured by similarity
between the sensations;[20] by a comparative feebleness of one of the
feelings; by the fact of habitual concomitance, the two sensations
occurring rarely, if ever, in isolation; and by the presence of a mental
disposition to view them as answering to one external object. These
considerations help us to explain the coalescence of the retinal
impressions and its limits, the fusion of partial tones, and so on.[21]

It is plain that this fusion of sensations, whatever its exact
conditions may be, gives rise to error or wrong interpretation of the
sense-impression. Thus, to take the points of two legs of a pair of
compasses for one point is clearly an illusion of perception. Here is
another and less familiar example. Very cold and smooth surfaces, as
those of metal, often appear to be wet. I never feel sure, after wiping
the blades of my skates, that they are perfectly dry, since they always
seem more or less damp to my hand. What is the reason of this? Helmholtz
explains the phenomenon by saying that the feeling we call by the name
of wetness is a compound sensation consisting of one of temperature and
one of touch proper. These sensations occurring together so frequently,
blend into one, and so we infer, according to the general instinctive
tendency already noticed, that there is one specific quality answering
to the feeling. And since the feeling is nearly always produced by
surfaces moistened by cold liquid, we refer it to this circumstance, and
speak of it as a feeling of wetness. Hence, when the particular
conjunction of sensations arises apart from this external circumstance,
we erroneously infer its presence.[22]

The most interesting case of illusion connected with the fusion of
simultaneous sensations, is that of single vision, or the deeply
organized habit of combining the sensations of what are called the
corresponding points of the two retinas. This coalescence of two
sensations is so far erroneous since it makes us overlook the existence
of two distinct external agencies acting on different parts of the
sensitive surface of the body. And this is the more striking in the case
of looking at solid objects, since here it is demonstrable that the
forces acting on the two retinas are not perfectly similar.
Nevertheless, such a coalescence plainly answers to the fact that these
external agencies usually arise in one and the same object, and this
unity of the object is, of course, the all-important thing to be sure

This habit may, however, beget palpable illusion in another way. In
certain exceptional cases the coalescence does not take place, as when I
look at a distant object and hold a pencil just before my eyes.[23] And
in this case the organized tendency to take one visual impression for
one object asserts its force, and I tend to fall into the illusion of
seeing two separate pencils. If I do not wholly lapse into the error, it
is because my experience has made me vaguely aware that double images
under these circumstances answer to one object, and that if there were
really two pencils present I should have four visual impressions.

Once more, it is a law of sensory stimulation that an impression
persists for an appreciable time after the cessation of the action of
the stimulus. This "after sensation" will clearly lead to illusion, in
so far as we tend to think of the stimulus as still at work. It forms,
indeed, as will be seen by-and-by, the simplest and lowest stage of
hallucination. Sometimes this becomes the first stage of a palpable
error. After listening to a child crying for some time the ear easily
deceives itself into supposing that the noise is continued when it has
actually ceased. Again, after taking a bandage from a finger, the
tingling and other sensations due to the pressure sometimes persist for
a good time, in which case they easily give rise to an illusion that the
finger is still bound.

It follows from this fact of the reverberation of the nervous structures
after the removal of a stimulus, that whenever two discontinuous
stimulations follow one another rapidly enough, they will appear
continuous. This fact is a fruitful source of optical illusion. The
appearance of a blending of the stripes of colours on a rotating disc or
top, of the formation of a ring of light by swinging round a piece of
burning wood, and the illusion of the toy known as the thaumatrope, or
wheel of life, all depend on this persistence of retinal impression.
Many of the startling effects of sleight of hand are undoubtedly due in
part to this principle. If two successive actions or sets of
circumstances to which the attention of the spectator is specially
directed follow one another by a very narrow interval of time, they
easily appear continuous, so that there seems absolutely no time for the
introduction of an intermediate step.[24]

There is another limit to sensibility which is in a manner the opposite
to the one just named. It is a law of nervous stimulation that a
continued activity of any structure results in less and less psychic
result, and that when a stimulus is always at work it ceases in time to
have any appreciable effect. The common illustration of this law is
drawn from the region of sound. A constant noise, as of a mill, ceases
to produce any conscious sensation. This fact, it is plain, may easily
become the commencement of an illusion. Not only may we mistake a
measure of noise for perfect silence,[25] we may misconceive the real
nature of external circumstances by overlooking some continuous

Curious illustrations of this effect are found in optical illusions,
namely, the errors we make respecting the movement of stationary objects
after continued movement of the eyes. When, for example, in a railway
carriage we have for some time been following the (apparent) movement of
objects, as trees, etc., and turn our eyes to an apparently stationary
object, as the carpet of the compartment, this seems to move in the
contrary direction to that of the trees. Helmholtz's explanation of this
illusion is that when we suppose that we are fixing our eye on the
carpet we are really continuing to move it over the surface by reason of
the organic tendency, already spoken of, to go on doing anything that
has been done. But since we are unaware of this prolonged series of
ocular movements, the muscular feelings having become faint, we take the
impression produced by the sliding of the picture over the retina to be
the result of a movement of the object.[26]

Another limit to our sensibility, which needs to be just touched on
here, is known by the name of the specific energy of the nerves. One and
the same nerve-fibre always reacts in a precisely similar way, whatever
the nature of the stimulus. Thus, when the optic nerve is stimulated in
any manner, whether by light, mechanical pressure, or an electric
current, the same effect, a sensation of light, follows.[27] In a usual
way, a given class of nerve-fibre is only stimulated by one kind of
stimulus. Thus, the retina, in ordinary circumstances, is stimulated by
light. Owing to this fact, there has arisen a deeply organized habit of
translating the impression in one particular way. Thus, I instinctively
regard a sensation received by means of the optic nerve as one caused by

Accordingly, whenever circumstances arise in which a like sensation is
produced by another kind of stimulus, we fall into illusion. The
phosphenes, or circles of light which are seen when the hinder part of
the eyeball is pressed, may be said to be illusory in so far as we
speak of them as perceptions of light, thus referring them to the
external physical agency which usually causes them. The same remark
applies to those "subjective sensations," as they are called, which are
known to have as their physical cause subjective stimuli, consisting, in
the case of sight, in varying conditions of the peripheral organ, as
increased blood-pressure. Strictly speaking, such simple feelings as
these appear to be, involve an ingredient of false perception: in saying
that we _perceive_ light at all, we go beyond the pure sensation,
interpreting this wrongly.

Very closely connected with this limitation of our sensibility is
another which refers to the consciousness of the local seat, or origin
of the impression. This has so far its basis in the sensation itself as
it is well known that (within the limits of local discrimination,
referred to above) sensations have a particular "local" colour, which
varies in the case of each of the nervous fibres by the stimulation of
which they arise.[28] But though this much is known through a difference
in the sensibility, nothing more is known. Nothing can certainly be
ascertained by a mere inspection of the sensation as to the distance the
nervous process has travelled, whether from the peripheral termination
of the fibre or from some intermediate point.

In a general way, we refer our sensations to the peripheral endings of
the nerves concerned, according to what physiologists have called "the
law of eccentricity." Thus I am said to feel the pain caused by a
bruise in the foot in the member itself. This applies also to some of
the sensations of the special senses. Thus, impressions of taste are
clearly localized in the corresponding peripheral terminations.

With respect to the sense of smell, and still more to those of hearing
and sight, where the impression is usually caused by an object at a
distance from the peripheral organ, our attention to this external cause
leads us to overlook in part the "bodily seat" of the sensation. Yet
even here we are dimly aware that the sensation is received by way of a
particular part of the sensitive surface, that is to say, by a
particular sense-organ. Thus, though referring an odour to a distant
flower, we perceive that the sensation of odour has its bodily origin in
the nose. And even in the case of hearing and sight, we vaguely refer
the impressions, as such, to the appropriate sense-organ. There is,
indeed, in these cases a double local reference, a faint one to the
peripheral organ which is acted on, and a more distinct one to the
object or the force in the environment which acts on this.

Now, it may be said that the act of localization is in itself distinctly
illusory, since it is known that the sensation first arises in
connection with the excitation of the sensory _centre_, and not of the
peripheral fibre.[29] Yet it must at least be allowed that this
localization of sensation answers to the important fact that, under
usual circumstances, the agency producing the sensation is applied at
this particular point of the organism, the knowledge of which point is
supposed by modern psychologists to have been very slowly learnt by the
individual and the race, through countless experiments with the moving
organ of touch, assisted by the eye.

Similarly, the reference of the impression, in the case of hearing and
sight, to an object in the environment, though, as we have seen, from
one point of view illusory, clearly answers to a fact of our habitual
experience; for in an immense preponderance of cases at least a visual
or auditory impression does arise through the action on the sense-organ
of a force (ether or air waves) proceeding from a distant object.

In some circumstances, however, even this element of practical truth
disappears, and the localization of the impression, both within and
without the organism, becomes altogether illusory. This result is
involved in the illusions, already spoken of, which arise from the
instinctive tendency to refer sensations to the ordinary kind of
stimulus. Thus, when a feeling resulting from a disturbance in the optic
nerve is interpreted as one of external light vaguely felt to be acting
on the eye, or one resulting from some action set up in the auditory
fibre as a sensation of external sound vaguely felt to be entering the
ear, we see that the error of localization is a consequence of the other
error already characterized.

As I have already observed, an excitation of a nerve at any other point
than the peripheral termination, occurs but rarely in normal life. One
familiar instance is the stimulation of the nerve running to the hand
and fingers, by a sharp blow on the elbow over which it passes. As
everybody knows, this gives rise to a sense of pain at the _extremities_
of the nerve. The most common illustration of such errors of
localization is found in subjective sensations, such as the impression
we sometimes have of something creeping over the skin, of a disagreeable
taste in the mouth, of luminous spots floating across the field of
vision, and so on. The exact physiological seat of these is often a
matter of conjecture only; yet it may safely be said that in many
instances the nervous excitation originates at some point considerably
short of its peripheral extremity: in which case there occurs the
illusion of referring the impressions to the peripheral sense-organ, and
to an external force acting on this.

The most striking instances of these errors of localization are found in
abnormal circumstances. It is well known that a man who has lost a leg
refers all sensations arising from a stimulation of the truncated fibres
to his lost foot, and in some cases has even to convince himself of the
non-existence of his lost member by sight or touch. Patients often
describe these experiences in very odd language. "If," says one of Dr.
Weir Mitchell's patients, "I should say I am more sure of the leg which
ain't than the one which air, I guess I should be about correct."[30]

There is good reason for supposing that this source of error plays a
prominent part in the illusions of the insane. Diseased centres may be
accompanied by disordered peripheral structures, and so subjective
sensation may frequently be the starting-point of the wildest illusions.
Thus, a patient's horror of poison may have its first origin in some
subjective gustatory sensation. Similarly, subjective tactual sensations
may give rise to gross illusions, as when a patient "feels" his body
attacked by foul and destructive creatures.

It may be well to remark that this mistaken interpretation of the seat
or origin of subjective sensation is closely related to hallucination.
In so far as the error involves the ascription of the sensation to a
force external to the sense-organ, this part of the mental process must,
when there is no such force present, be viewed as hallucinatory. Thus,
the feeling of something creeping over the skin is an hallucination in
the sense that it implies the idea of an object external to the skin.
Similarly, the projection of an ocular impression due to retinal
disturbance into the external field of vision, may rightly be named an
hallucination. But the case is not always so clear as this. Thus, for
example, when a gustatory sensation is the result of an altered
condition of the saliva, it may be said that the error is as much an
illusion as an hallucination.[31]

In a wide sense, again, all errors connected with those subjective
sensations which arise from a stimulation of the peripheral regions of
the nerve may be called illusions rather than hallucinations. Or, if
they must be called hallucinations, they may be distinguished as
"peripheral" from those "central" hallucinations which arise through an
internal automatic excitation of the sensory centre. It is plain from
this that the region of subjective sensation is an ambiguous region,
where illusion and hallucination mix and become confused. To this point
I shall have occasion to return by-and-by.

I have now probably said enough respecting the illusions that arise
through the fact of there being fixed limits to our sensibility. The
_rationale_ of these illusions is that whenever the limit is reached, we
tend to ignore it and to interpret the impression in the customary way.

_Variations of Sensibility._

We will now pass to a number of illusions which depend on something
variable in the condition of our sensibility, or some more or less
exceptional organic circumstance. These variations may be momentary and
transient or comparatively permanent. The illusion arises in each case
from our ignoring the variation, and treating a given sensation under
all circumstances as answering to one objective cause.

First of all, the variation of organic state may affect our mental
representation of the strength of the stimulus or external cause. Here
the fluctuation may be a temporary or a permanent one. The first case is
illustrated in the familiar example of taking a room to be brighter
than it is when emerging from a dark one. Another striking example is
that of our sense of the temperature of objects, which is known to be
strictly relative to a previous sensation, or more correctly to the
momentary condition of the organ. Yet, though every intelligent person
knows this, the deeply rooted habit of making sensation the measure of
objective quality asserts its sway, and frequently leads us into
illusion. The well-known experiment of first plunging one hand in cold
water, the other in hot, and then dipping them both in tepid, is a
startling example of this organized tendency. For here we are strongly
disposed to accept the palpable contradiction that the same water is at
once warm and cool.

Far more important than these temporary fluctuations of sensibility are
the permanent alterations. Excessive fatigue, want of proper nutrition,
and certain poisons are well known to be causes of such changes. They
appear most commonly under two forms, exalted sensibility, or
hyperæsthesia, and depressed sensibility, or anæsthesia. In these
conditions flagrant errors are made as to the real magnitude of the
causes of the sensations. These variations may occur in normal life to
some extent. In fairly good health we experience at times strange
exaltations of tactual sensibility, so that a very slight stimulus, such
as the contact of the bed-clothes, becomes greatly exaggerated.

In diseased states of the nervous system these variations of sensibility
become much more striking. The patient who has hyperæsthesia fears to
touch a perfectly smooth surface, or he takes a knock at the door to be
a clap of thunder. The hypochondriac may, through an increase of
organic sensibility, translate organic sensations as the effect of some
living creature gnawing at his vitals. Again, states of anæsthesia lead
to odd illusions among the insane. The common supposition that the body
is dead, or made of wood or of glass, is clearly referable in part to
lowered sensibility of the organism.[32]

It is worth adding, perhaps, that these variations in sensibility give
rise not only to sensory but also to motor illusions. To take a homely
instance, the last miles of a long walk seem much longer than the first,
not only because the sense of fatigue leading us to dwell on the
transition of time tends to magnify the apparent duration, but because
the fatigued muscles and connected nerves yield a new set of sensations
which constitute an exaggerated standard of measurement. A number of
optical illusions illustrate the same thing. Our visual sense of
direction is determined in part by the feelings accompanying the action
of the ocular muscles, and so is closely connected with the perception
of movement, which has already been touched on. If an ocular muscle is
partially paralyzed it takes a much greater "effort" to effect a given
extent of movement than when the muscle is sound. Hence any movement
performed by the eye seems exaggerated. Hence, too, in this condition
objects are seen in a wrong direction; for the patient reasons that they
are where they would seem to be if he had executed a wider movement than
he really has. This may easily be proved by asking him to try to seize
the object with, his hand. The effect is exaggerated when complete
paralysis sets in, and no actual movement occurs in obedience to the
impulse from within.[33]

Variations in the condition of the nerve affect not only the degree, but
also the quality of the sensation, and this fact gives rise to a new
kind of illusion. The curious phenomena of colour-contrast illustrate
momentary alterations of sensibility. When, after looking at a green
colour for a time, I turn my eye to a grey surface and see this of the
complementary rose-red hue, the effect is supposed to be due to a
temporary fatigue of the retina in relation to those ingredients of the
total light in the second case which answer to the partial light in the
first (the green rays).[34]

These momentary modifications of sensibility are of no practical
significance, being almost instantly corrected. Other modifications are
more permanent. It was found by Himly that when the retina is
overexcitable every stimulus is raised in the spectrum scale of colours.
Thus, violet becomes red. An exactly opposite effect is observed when
the retina is torpid.[35] Certain poisons are known to affect the
quality of the colour-impression. Thus, santonin, when taken in any
quantity, makes all colourless objects look yellow. Severe pathological
disturbances are known to involve, in addition to hyperæsthesia and
anæsthesia, what, has been called paræsthesia, that is to say, that
condition in which the quality of sensation is greatly changed. Thus,
for example, to one in this state all food appears to have a metallic
taste, and so on.

If we now glance back at the various groups of illusions just
illustrated, we find that they all have this feature in common: they
depend on the general mental law that when we have to do with the
unfrequent, the unimportant, and therefore unattended to, and the
exceptional, we employ the ordinary, the familiar, and the well-known as
our standard. Thus, whether we are dealing with sensations that fall
below the ordinary limits of our mental experience, or with those which
arise in some exceptional state of the organism, we carry the habits
formed in the much wider region of average every-day perception with us.
In a word, illusion in these cases always arises through what may,
figuratively at least, be described as the application of a rule, valid
for the majority of cases, to an exceptional case.

In the varieties of illusion just considered, the circumstance that
gives the peculiarity to the case thus wrongly interpreted has been
referred to the organism. In the illusions to which we now pass, it will
be referred to the environment. At the same time, it is plain that there
is no very sharp distinction between the two classes. Thus, the visual
illusion produced by pressing the eyeball might be regarded not only as
the result of the organic law of the "specific energy" of the nerves,
but, with almost equal appropriateness, as the consequence of an
exceptional state of things in the environment, namely, the pressure of
a body on the retina. As I have already observed, the classification
here adopted is to be viewed simply as a rough expedient for securing
something like a systematic review of the phenomena.



A. _Passive Illusions (b) as determined by the Environment._

In the following groups of illusion we may look away from nervous
processes and organic disturbances, regarding the effect of any external
stimulus as characteristic, that is, as clearly marked off from the
effects of other stimuli, and as constant for the same stimulus. The
source of the illusion will be looked for in something exceptional in
the external circumstances, whereby one object or condition of an object
imitates the effect of another object or condition, to which, owing to a
large preponderance of experience, we at once refer it.

_Exceptional Relation of Stimulus to Organ._

A transition from the preceding to the following class of illusions is
to be met with in those errors which arise from a very exceptional
relation between the stimulus and the organ of sense. Such a state of
things is naturally interpreted by help of more common and familiar
relations, and so error arises.

For example, we may grossly misinterpret the intensity of a stimulus
under certain circumstances. Thus, when a man crunches a biscuit, he has
an uncomfortable feeling that the noise as of all the structures of his
head being violently smashed is the same to other ears, and he may even
act on his illusory perception, by keeping at a respectful distance from
all observers. And even though he be a physiologist, and knows that the
force of sensation in this case is due to the propagation of vibrations
to the auditory centre by other channels than the usual one of the ear,
the deeply organized impulse to measure the strength of an external
stimulus by the intensity of the sensation asserts its force.

Again, if we turn to the process of perceptional construction properly
so called, the reference of the sensation to a material object lying in
a certain direction, etc., we find a similar transitional form of
illusion. The most interesting case of this in visual perception is that
of a disturbance or displacement of the organ by external force. For
example, an illusory sense of direction arises by the simple action of
closing one eye, say the left, and pressing the other eyeball with one
of the fingers a little outwards, that is to the right. The result of
this movement is, of course, to transfer the retinal picture to new
nervous elements further to the right. And since, in this instance, the
displacement is not produced in the ordinary way by the activity of the
ocular muscle making itself known by certain feelings of movement, it is
disregarded altogether, and the direction of the objects is judged as
though the eye were stationary.

A somewhat similar illusion as to direction occurs in auditory
perception. The sense of direction by the ear is known to be due in part
to the action of the auricle, or projecting part of the ear. This
collects the air-waves, and so adds to the intensity of the sounds,
especially those coming from in front, and thus assists in the
estimation of direction. This being so, if an artificial auricle is
placed in front of the ears; if, for example, the two hands are each
bent into a sort of auricle, and placed in front of the ears, the back
of the hand being in front, the sense of direction (as well as of
distance) is confused. Thus, sounds really travelling from a point in
front of the head will appear to come from behind it.

Again, the perception of the unity of an object is liable to be
falsified by the introduction of exceptional circumstances into the
sense-organ. This is illustrated in the well-known experiment of
crossing two fingers, say the third and fourth, and placing a marble or
other small round object between them. Under ordinary circumstances, the
two lateral surfaces (that is, the outer surfaces of the two fingers)
now pressed by the marble, can only be acted on simultaneously by _two_
objects having convex surfaces. Consequently, we cannot help feeling the
presence of two objects in this exceptional instance. The illusion is
analogous to that of the stereoscope, to be spoken of presently.

_Exceptional External Arrangements._

Passing now to those cases where the exceptional circumstance is
altogether exterior to the organ, we find a familiar example in the
illusions connected with the action of well-known physical forces, as
the refraction of light, and the reflection of light and sound. A stick
half-immersed in water always _looks_ broken, however well we may know
that the appearance is due to the bending of the rays of light.
Similarly, an echo always sounds as though it came from some object in
the direction in which the air-waves finally travel to the ear, though
we are perfectly sure that these undulations have taken a circuitous
course. It is hardly necessary to remind the reader that the deeply
organized tendency to mistake the direction of the visible or audible
object in these cases has from remote ages been made use of as a means
of popular delusion. Thus, we are told by Sir D. Brewster, in his
entertaining _Letters on Natural Magic_ (letter iv.), that the concave
mirror was probably used as the instrument for bringing the gods before
the people. The throwing of the images formed by such mirrors upon smoke
or against fire, so as to make them more distinct, seems to have been a
favourite device in the ancient art of necromancy.

Closely connected with these illusions of direction with respect to
resting objects, are those into which we are apt to fall respecting the
movements of objects. What looks like the movement of something across
the field of vision is made known to us either by the feeling of the
ocular muscles, if the eye follows the object, or through the sequence
of locally distinct retinal impressions, if the eye is stationary. Now,
either of these effects may result, not only from the actual movement of
the object in a particular direction, but from our own movement in an
opposite direction; or, again, from our both moving in the first
direction, the object more rapidly than ourselves; or, finally, from our
both moving in an opposite direction to this, ourselves more rapidly
than the object. There is thus always a variety of conceivable
explanations, and the action of past experience and association shows
itself very plainly in the determination of the direction of
interpretation. Thus, it is our instinctive tendency to take apparent
movement for real movement, except when the fact of our own movement is
clearly present to consciousness, as when we are walking, or when we are
sitting behind a horse whose movement we see. And so when the sense of
our own movement becomes indistinct, as in a railway carriage, we
naturally drift into the illusion that objects, such as trees, telegraph
posts, and so on, are moving, when they are perfectly still. Under the
same circumstances, we are apt to suppose that a train which is just
shooting ahead of us is moving slowly.

Similar uncertainties arise with respect to the relative movement of two
objects, the eye being supposed to be fixed in space. When two objects
seem to pass one another, it may be that they are both moving in
contrary directions, or that one only is moving, or finally, that both
are moving in the same direction, the one faster than the other.
Experience and habit here again suggest the interpretation which is most
easy, and not unfrequently produce illusion. Thus, when we watch clouds
scudding over the face of the moon, the latter seems moving rather than
the former, and the illusion only disappears when we fix the eye on the
moon and recognize that it is really stationary. The probable reason of
this is, as Wundt suggests, that experience has made it far easier for
us to think of small objects like the moon moving rapidly, than of large
masses like the clouds.[36]

The perception of distance, still more than that of direction, is liable
to be illusory. Indeed, the visual recognition of distance, together
with that of solidity, has been the great region for the study of "the
deceptions of the senses." Without treating the subject fully here, I
shall try to describe briefly the nature and source of these

Confining ourselves first of all to near objects, we know that the
smaller differences of distance in these cases are, if the eyes are at
rest, perceived by means of the dissimilar pictures projected on the two
retinas; or if they move, by this means, together with the muscular
feelings that accompany different degrees of convergence of the two
eyes. This was demonstrated by the famous experiments of Wheatstone.
Thus, by means of the now familiar stereoscope, he was able to produce a
perfect illusion of relief. The stereoscope may be said to introduce an
exceptional state of things into the spectator's environment. It
imitates, by means of two flat drawings, the dissimilar retinal pictures
projected by a single solid receding object, and the lenses through
which the eyes look are so constructed as to compel them to converge as
though looking on a single object. And so powerful is the tendency to
interpret this impression as one of solidity, that even though we are
aware of the presence of the stereoscopic apparatus, we cannot help
seeing the two drawings as a single solid object.

In the case of more remote objects, there is no dissimilarity of the
retinal pictures or feelings of convergence to assist the eye in
determining distance. Here its judgment, which now becomes more of a
process of _conscious_ inference, is determined by a number of
circumstances which, through experience and association, have become the
signs of differences of depth in space. Among these are the degree of
indistinctness of the impression, the apparent or retinal magnitude (if
the object is a familiar one), the relations of linear perspective, as
the interruption of the outline of far objects by that of near objects,
and so on. In a process so complicated there is clearly ample room for
error, and wrong estimates of distance whenever unusual circumstances
are present are familiar to all. Thus, the inexperienced English
tourist, when in the clear atmosphere of Switzerland, where the
impressions from distant objects are more distinct than at home,
naturally falls into the illusion that the mountains are much nearer
than they are, and so fails to realize their true altitude.

_Illusions of Art._

The imitation of solidity and depth by art is a curious and interesting
illustration of the mode of production of illusion. Here we are not, of
course, concerned with the question how far illusion is desirable in
art, but only with its capabilities of illusory presentment; which
capabilities, it may be added, have been fully illustrated in the
history of art. The full treatment of this subject would form a chapter
in itself; here I can only touch on its main features.

Pictorial art working on a flat surface cannot, it is plain, imitate the
stereoscope, and produce a perfect sense of solidity. Yet it manages to
produce a pretty strong illusion. It illustrates in a striking manner
the ease with which the eye conceives relations of depth or relief and
solidity. If, for example, on a carpet, wall-paper, or dress, bright
lines are laid on a dark colour as ground, we easily imagine that they
are advancing. The reason of this seems to be that in our daily
experience advancing surfaces catch and reflect the light, whereas
retiring surfaces are in shadow.[38]

The same principle is illustrated in one of the means used by the artist
to produce a strong sense of relief, namely, the cast shadow. A circle
drawn with chalk with a powerful cast shadow on one side will, without
any shading or modelling of the form, appear to stand out from the
paper, thus:

[Illustration: FIG. 1.]

The reason is that the presence of such a shadow so forcibly suggests to
the mind that the object is a prominent one intervening between the
light and the shaded surface.[39]

Even without differences of light and shade, by a mere arrangement of
lines, we may produce a powerful sense of relief or solidity. A striking
example of this is the way in which two intersecting lines sometimes
appear to recede from the eye, as the lines _a a'_, _b b'_, in the next
drawing, which seem to belong to a regular pattern on the ground, at
which the eye is looking from above and obliquely.

[Illustration: FIG. 2.]

Again, the correct delineation of the projection of a regular
geometrical figure, as a cube, suffices to give the eye a sense of
relief. This effect is found to be the more striking in proportion to
the familiarity of the form. The following drawing of a long box-shaped
solid at once seems to stand out to the eye.

[Illustration: FIG. 3.]

This habitual interpretation of the flat in art as answering to objects
in relief, or having depth, can only be understood when it is remembered
that our daily experience gives us myriads of instances in which the
effect of such flat representations answers to solid receding forms.
That is to say, in the case of all distant objects, in the perception of
which the dissimilarity of the retinal pictures and the feeling of
convergence take no part, we have to interpret solidity, and relations
of nearer and further, by such signs as linear perspective and cast
shadow. On the other hand, it is only in the artificial life of indoors,
on our picture-covered walls, that we experience such effects without
discovering corresponding realities. Hence a deeply organized habit of
taking these impressions as answering to the solid and not to the flat.
If our experience had been quite different; if, for example, we had
been brought up in an empty room, amid painted walls, and had been
excluded from the sight of the world of receding objects outside, we
might easily have formed an exactly opposite habit of taking the actual
mountains, trees, etc., of the distant scene to be pictures laid on a
flat surface.

[Illustration: FIG. 4.]

It follows from this that, with respect to the distant parts of a scene,
pictorial art possesses the means of perfect imitation; and here we see
that a complete illusory effect is obtainable. I need but to refer to
the well-known devices of linear and aerial perspective, by which this
result is secured.[40] The value of these means of producing illusion at
the command of the painter, may be illustrated by the following fact,
which I borrow from Helmholtz. If you place two pieces of cardboard
which correspond to portions of one form at the sides and in front of a
third piece, in the way represented above, so as just to allow the eye
to follow the contour of this last, and then look at this arrangement
from a point at some little distance with one eye, you easily suppose
that it stands in front of the side pieces. The explanation of the
illusion is that this particular arrangement powerfully suggests that
the outline of the whole figure, of which the two side pieces are parts,
is broken by an intervening object. Owing to the force of these and
other suggestions, it is easy for the spectator, when attending to the
background of a landscape painting, to give himself up for a moment to
the pleasant delusion that he is looking at an actual receding scene.

In connection with pictorial delusion, I may refer to the well-known
fact, that the eye in a portrait seems to follow the spectator, or that
a gun, with its muzzle pointing straight outwards, appears to turn as
the spectator moves.[41] These tricks of art have puzzled many people,
yet their effect is easily understood, and has been very clearly
explained by Sir D. Brewster, in the work already referred to (letter
v.). They depend on the fact that a painting, being a flat projection
only and not a solid, continues to present the front view of an object
which it represents wherever the spectator happens to stand. Were the
eye in the portrait a real eye, a side movement of the spectator would,
it is evident, cause him to see less of the pupil and more of the side
of the eyeball, and he would only continue to see the full pupil when
the eye followed him. We regard the eye in the picture as a real eye
having relief, and judge accordingly.

We may fall into similar illusions respecting distance in auditory
perception. A change of wind, an unusual stillness in the air, is quite
sufficient to produce the sense that sounding objects are nearer than
they actually are. The art of the ventriloquist manifestly aims at
producing this kind of illusion. By imitating the dull effect of a
distant voice, he is able to excite in the minds of his audience a
powerful conviction that the sounds proceed from a distant point. There
is little doubt that ventriloquism has played a conspicuous part in the
arts of divination and magic.

_Misconception of Local Arrangement._

Let us now pass to a class of illusions closely related to those having
to do with distance, but involving some special kind of circumstance
which powerfully suggests a particular arrangement in space. One of the
most striking examples of these is the erroneous localization of a
quality in space, that is to say, the reference of it to an object
nearer, or further off than the right one. Thus, when we look through a
piece of yellow glass at a dull, wintry landscape, we are disposed to
imagine that we are looking at a sunny scene of preternatural warmth. A
moment's reflection would tell us that the yellow tint, with which the
objects appear to be suffused, comes from the presence of the glass;
yet, in spite of this, the illusion persists with a curious force. The
explanation is, of course, that the circumstances are exceptional, that
in a vast majority of cases the impression of colour belongs to the
object and not to an intervening medium,[42] and that consequently we
tend to ignore the glass, and to refer the colour to the objects

When, however, the fact of the existence of a coloured medium is
distinctly present to the mind, we easily learn to allow for this, and
to recognize one coloured surface correctly through a recognized medium.
Thus, we appear to ourselves to see the reflected images of the wall,
etc., of a room, in a bright mahogany table, not suffused with a reddish
yellow tint, as they actually are--and may be seen to be by the simple
device of looking at a small bit of the image through a tube, but in
their ordinary colour. We may be said to fall into illusion here in so
far as we overlook the exact quality of the impression actually made on
the eye. This point will be touched on presently. Here I am concerned to
show that this habit of allowing for the coloured medium may, in its
turn, occasionally lead to plain and palpable illusion.

The most striking example of this error is to be met with among the
curious phenomena of colour-contrast already referred to. In many of
these cases the appearance of the contrasting colour is, as I have
observed, due to a temporary modification of the nervous substance. Yet
it is found that this organic factor does not wholly account for the
phenomena. For example, Meyer made the following experiment. He covered
a piece of green paper by a sheet of thin transparent white paper. The
colour of this double surface was, of course, a pale green. He then
introduced a scrap of grey paper between the two sheets, and found that,
instead of looking whitish as it really was, it looked rose-red.
Whatever the colour of the under sheet the grey scrap took the
complementary hue. If, however, the piece of grey paper is put outside
the thin sheet, it looks grey; and what is most remarkable is that when
a second piece is put outside, the scrap inside no longer wears the
complementary hue.

There is here evidently something more than a change of organic
conditions; there is an action of experience and suggestion. The reason
of our seeing the scrap rose-red in one case and neutral grey in
another, is that in the first instance we vividly represent to ourselves
that we are looking at it through a greenish veil (which is, of course,
a part of the illusion); for rose-red seen through a greenish medium
would, as a matter of fact, be light grey, as this scrap is. Even if we
allow that there always exists after an impression of colour a temporary
organic disposition to see the complementary hue, this does not suffice
as an explanation of these cases; we have to conclude further that
imagination, led by the usual run of our experience, is here a
co-operant factor, and helps to determine whether the complementary tint
shall be seen or not.

_Misinterpretation of Form._

More complex and circumscribed associations take part in those errors
which we occasionally commit respecting the particular form of objects.
This has already been touched on in dealing with artistic illusion. The
disposition of the eye to attribute solidity to a flat drawing is the
more powerful in proportion to the familiarity of the form. Thus, an
outline drawing of a building is apt to stand out with special force.

Another curious illustration of this is the phenomenon known as the
conversion of the concave mould or matrix of a medal into the
corresponding convex relief. If, says Helmholtz, the mould of a medal be
illuminated by a light falling obliquely so as to produce strong
shadows, and if we regard this with one eye, we easily fall into the
illusion that it is the original raised design, illuminated from _the
opposite side_. As a matter of fact, the visual impression produced by a
concave form with the light falling on one side, very closely resembles
that produced by a corresponding convex form with the light falling on
the other side. At the same time, it is found that the opposite mode of
conversion, that is to say, the transformation of the raised into the
depressed form, though occurring occasionally, is much less frequent.
Now, it may be asked, why should we tend to transform the concave into
the convex, rather than the convex into the concave? The reader may
easily anticipate the answer from what has been said about the deeply
fixed tendency of the eye to solidify a plane surface. We are rendered
much more familiar, both by nature and by art, with raised (_cameo_)
design than with depressed design (_intaglio_), and we instinctively
interpret the less familiar form by the more familiar. This explanation
appears to be borne out by the fact emphasized by Schroeder that the
illusion is much more powerful if the design is that of some well-known
object, as the human head or figure, or an animal form, or leaves.[43]

Another illustration of this kind of illusion recently occurred in my
own experience. Nearly opposite to my window came a narrow space between
two detached houses. This was, of course, darker than the front of the
houses, and the receding parallel lines of the bricks appeared to cross
this marrow vertical shaft obliquely. I could never look at this without
seeing it as a convex column, round which the parallel lines wound
obliquely. Others saw it as I did, though not always with the same
overpowering effect. I can only account for this illusion by help of the
general tendency of the eye to solidify impressions drawn from the flat,
together with the effect of special types of experience, more
particularly the perception of cylindrical forms in trees, columns, etc.

It may be added that a somewhat similar illustration of the action of
special types of experience on the perception of individual form may be
found in the region of hearing. The powerful disposition to take the
finely graduated cadences of sound produced by the wind for the
utterances of a Iranian voice, is due to the fact that this particular
form and arrangement of sound has deeply impressed itself on our minds,
in connection with numberless utterances of human feeling.

_Illusions of Recognition._

As a last illustration of comparatively passive illusions, I may refer
to the errors which we occasionally commit in recognizing objects. As I
have already observed, the process of full and clear recognition,
specific and individual, involves a classing of a number of distinct
aspects of the object, such as colour, form, etc. Accordingly, when in a
perfectly calm state of mind we fall into illusion with respect to any
object plainly visible, it must be through some accidental resemblance
between the object and the other object or class of objects with which
we identify it. In the case of individual identification such illusions
are, of course, comparatively rare, since here there are involved so
many characteristic differences. On the other hand, in the case of
specific recognition there is ample room for error, especially in those
kinds of more subtle recognition to which I have already referred. To
"recognize" a person as a Frenchman or a military man, for example, is
often an erroneous process. Logicians have included this kind of error
under what they call "fallacies of observation."

Errors of recognition, both specific and individual, are, of course,
more easy in the case of distant objects or objects otherwise
indistinctly seen. It is noticeable in these cases that, even when
perfectly cool and free from emotional excitement, we tend to interpret
such indistinct impressions according to certain favourite types of
experience, as the human face and figure. Our interpretative imagination
easily sees traces of the human form in cloud, rock, or tree-stump.

Again, even when there is no error of recognition, in the sense of
confusing one object with other objects, there may be partial illusion.
I have remarked that the process of recognizing an object commonly
involves an overlooking of points of diversity in the object, or aspect
of the object, now present. And sometimes this inattention to what is
actually present includes an error as to the actual visual sensation of
the moment. Thus, for example, when I look at a sheet of white paper in
a feebly lit room, I seem to see its whiteness. If, however, I bring it
near the window, and let the sun fall on a part of it, I at once
recognize that what I have been seeing is not white, but a decided grey.
Similarly, when I look at a brick viaduct a mile or two off, I appear to
myself to recognize its redness. In fact, however, the impression of
colour which I receive from the object is not that of brick-red at all,
but a much less decided tint; which I may easily prove by bending my
head downwards and letting the scene image itself on the retina in an
unusual way, in which case the recognition of the object as a viaduct
being less distinct, I am better able to attend to the exact shade of
the colour.

Nowhere is this inattention to the sensation of the moment exhibited in
so striking a manner as in pictorial art. A picture of Meissonier may
give the eye a representation of a scene in which the objects, as the
human figures and horses, have a distinctness that belongs to near
objects, but an apparent magnitude that belongs to distant objects. So
again, it is found that the degree of luminosity or brightness of a
pictorial representation differs in general enormously from that of the
actual objects. Thus, according to the calculations of Helmholtz,[44] a
picture representing a Bedouin's white raiment in blinding sunshine,
will, when seen in a fairly lit gallery, have a degree of luminosity
reaching only to about one-thirtieth of that of the actual object. On
the other hand, a painting representing marble ruins illuminated by
moonlight, will, under the same conditions of illumination, have a
luminosity amounting to as much as from ten to twenty thousand times
that of the object. Yet the spectator does not notice these stupendous
discrepancies. The representation, in spite of its vast difference, at
once carries the mind on to the actuality, and the spectator may even
appear to himself, in moments of complete absorption, to be looking at
the actual scene.

The truly startling part of these illusions is, that the direct result
of sensory stimulation appears to be actually displaced by a mental
image. Thus, in the case of Meyer's experiment, of looking at the
distant viaduct, and of recognizing an artistic representation,
imagination seems in a measure to take the place of sensation, or to
blind the mind to what is actually before it.

The mystery of the process, however, greatly disappears when it is
remembered that what we call a conscious "sensation" is really
compounded of a result of sensory stimulation and a result of central
reaction, of a purely passive impression and the mental activity
involved in attending to this and classing it.[45] This being so, a
sensation may be modified by anything exceptional in the mode of central
reaction of the moment. Now, in all the cases just considered, we have
one common feature, a powerful suggestion of the presence of a
particular object or local arrangement. This suggestion, taking the form
of a vivid mental image, dominates and overpowers the passive
impression. Thus, in Meyer's experiment, the mind is possessed by the
supposition that we are looking at the grey spot through a greenish
medium. So in the case of the distant viaduct, we are under the mastery
of the idea that what we see in the distance is a red brick structure.
Once more, in the instance of looking at the picture, the spectator's
imagination is enchained by the vivid representation of the object for
which the picture stands, as the marble ruins in the moonlight or the
Bedouin in the desert.

It may be well to add that this mental uncertainty as to the exact
nature of a present impression is necessitated by the very conditions of
accurate perception. If, as I have said, all recognition takes place by
overlooking points of diversity, the mind must, in course of time,
acquire a habit of not attending to the exact quality of
sense-impressions in all cases where the interpretation seems plain and
obvious. Or, to use Helmholtz's words, our sensations are, in a general
way, of interest to us only as signs of things, and if we are sure of
the thing, we readily overlook the precise nature of the impression. In
short, we get into the way of attending only to what is essential,
constant, and characteristic in objects, and disregarding what is
variable and accidental.[46] Thus, we attend, in the first place, to the
form of objects, the most constant and characteristic element of all,
being comparatively inattentive to colour, which varies with distance,
atmospheric changes, and mode of illumination. So we attend to the
relative magnitude of objects rather than to the absolute, and to the
relative intensities of light and shade rather than to the absolute; for
in so doing we are noting what is constant for all distances and modes
of illumination, and overlooking what is variable. And the success of
pictorial art depends on the observance of this law of perception.

These remarks at once point out the limits of these illusions. In normal
circumstances, an act of imagination, however vivid, cannot create the
semblance of a sensation which is altogether absent; it can only
slightly modify the actual impression by interfering with that process
of comparison and classification which enters into all definite
determination of sensational quality.

Another great fact that has come to light in the investigation of these
illusions is that oft-recurring and familiar types of experience leave
permanent dispositions in the mind. As I said when describing the
process of perception, what has been frequently perceived is perceived
more and more readily. It follows from this that the mind will be
habitually disposed to form the corresponding mental images, and to
interpret impressions by help of these. The range of artistic suggestion
depends on this. A clever draughtsman can indicate a face by a few rough
touches, and this is due to the fact that the spectator's mind is so
familiarized, through recurring experience and special interest, with
the object, that it is ready to construct the requisite mental image at
the slightest external suggestion. And hence the risk of hasty and
illusory interpretation.

These observations naturally conduct us to the consideration of the
second great group of sense-illusions, which I have marked off as active
illusions, where the action of a pre-existing intellectual disposition
becomes much more clearly marked, and assumes the form of a free
imaginative transformation of reality.



B. _Active Illusions._

When giving an account of the mechanism of perception, I spoke of an
independent action of the imagination which tends to anticipate the
process of suggestion from without. Thus, when expecting a particular
friend, I recognize his form much more readily than when my mind has not
been preoccupied with his image.

A little consideration will show that this process must be highly
favourable to illusion. To begin with, even if the preperception be
correct, that is to say, if it answer to the perception, the mere fact
of vivid expectation will affect the exact moment of the completed act
of perception. And recent experiment shows that in certain cases such a
previous activity of expectant attention may even lead to the illusory
belief that the perception takes place before it actually does.[47]

A more palpable source of error resides in the risk of the formation of
an inappropriate preperception. If a wrong mental image happens to have
been formed and vividly entertained, and if the actual impression fits
in to a certain extent with this independently formed preperception, we
may have a fusion of the two which exactly simulates the form of a
complete percept. Thus, for example, in the case just supposed, if
another person, bearing some resemblance to our expected friend, chances
to come into view, we may probably stumble into the error of taking one
person for another.

On the physical side, we may, agreeably to the hypothesis mentioned
above, express this result by saying that, owing to a partial identity
in the nervous processes involved in the anticipatory image and the
impression, the two tend to run one into the other, constituting one
continuous process.

There are different ways in which this independent activity of the
imagination may falsify our perceptions. Thus, we may voluntarily choose
to entertain a certain image for the moment, and to look at the
impression in a particular way, and within certain limits such
capricious selection of an interpretation is effectual in giving a
special significance to an impression. Or the process of independent
preperception may go on apart from our volitions, and perhaps in spite
of these, in which case the illusion has something of the irresistible
necessity of a passive illusion. Let us consider separately each mode
of production.

_Voluntary Selection of Interpretation._

The action of a capricious exercise of the imagination in relation to an
impression is illustrated in those cases where experience and suggestion
offer to the interpreting mind an uncertain sound, that is to say, where
the present sense-signs are ambiguous. Here we obviously have a choice
of interpretation. And it is found that, in these cases, what we see
depends very much on what we wish to see. The interpretation adopted is
still, in a sense, the result of suggestion, but of one particular
suggestion which the fancy of the moment determines. Or, to put it
another way, the caprice of the moment causes the attention to focus
itself in a particular manner, to direct itself specially to certain
aspects and relations of objects.

The eye's interpretation of movement, already referred to, obviously
offers a wide field for this play of selective imagination. When looking
out of the window of a railway carriage, I can at will picture to my
mind the trees and telegraph posts as moving objects. Sometimes the true
interpretation is so uncertain that the least inclination to view the
phenomenon in one way determines the result. This is illustrated in a
curious observation of Sinsteden. One evening, on approaching a windmill
obliquely from one side, which under these circumstances he saw only as
a dark silhouette against a bright sky, he noticed that the sails
appeared to go, now in one direction, now in another, according as he
imagined himself looking at the front or at the back of the

In the interpretation of geometrical drawings, as those of crystals,
there is, as I have observed, a general tendency to view the flat
delineation as answering to a raised object, or a body in relief,
according to the common run of our experience. Yet there are cases where
experience is less decided, and where, consequently, we may regard any
particular line as advancing or receding. And it is found that when we
vividly imagine that the drawing is that of a convex or concave surface,
we see it to be so, with all the force of a complete perception. The
least disposition to see it in the other way will suffice to reverse the
interpretation. Thus, in the following drawing, the reader can easily
see at will something answering to a truncated pyramid, or to the
interior of a cooking vessel.

[Illustration: FIG. 5.]

Similarly, in the accompanying figure of a transparent solid, I can at
will select either of the two surfaces which approximately face the eye
and regard it as the nearer, the other appearing as the hinder surface
looked at through the body.

[Illustration: FIG. 6.]

Again, in the next drawing, taken from Schroeder, one may, by an effort
of will, see the diagonal step-like pattern, either as the view from
above of the edge of an advancing piece of wall at _a_, or as the view
from below of the edge of an advancing (overhanging) piece of wall at

[Illustration: FIG. 7.]

These last drawings are not in true perspective on either of the
suppositions adopted, wherefore the choice is easier. But even when an
outline form is in perspective, a strenuous effort of imagination may
suffice to bring about a conversion of the appearance. Thus, if the
reader will look at the drawing of the box-like solid (Fig. 3, p. 79),
he will find that, after a trial or two, he succeeds in seeing it as a
_concave_ figure representing the coyer and two sides of a box as looked
at from within.[49]

Many of my readers, probably, share in my power of variously
interpreting the relative position of bands or stripes on fabrics such
as wall-papers, according to wish. I find that it is possible to view
now this stripe or set of stripes as standing out in relief upon the
others as a ground, now these others as advancing out of the first as a
background. The difficulty of selecting either interpretation at will
becomes greater, of course, in those cases where there is a powerful
suggestion of some particular local arrangement, as, for example, the
case of patterns much brighter than the ground, and especially of such
as represent known objects, as flowers. Yet even here a strong effort of
imagination will often suffice to bring about a conversion of the first

A somewhat similar choice of interpretation offers itself in looking at
elaborate decorative patterns. When we strongly imagine any number of
details to be elements of one figure, they seem to become so; and a
given detail positively appears to alter in character according as it is
viewed as an element of a more or less complex figure.

These examples show what force belongs to a vivid preconception, if this
happens to fit only very roughly the impression of the moment, that is
to say, if the interpretative image is one of the possible suggestions
of the impression. The play of imagination takes a wider range in those
cases where the impression is very indefinite in character, easily
allowing of a considerable variety of imaginative interpretation.

I referred at the beginning of this account of sense-illusions to the
readiness with which the mind deceives itself with respect to the nature
and causes of the vague sensations which usually form the dim background
of our mental life. A person of lively imagination, by trying to view
these in a particular way, and by selectively attending to those aspects
of the sensation which answer to the caprice of the moment, may give a
variety of interpretations to one and the same set of sensations. For
example, it is very easy to get confused with respect to those tactual
and motor feelings which inform us of the position of our bodily
members. And so, when lying in bed, and attending to the sensations
connected with the legs, we may easily delude ourselves into supposing
that these members are arranged in a most eccentric fashion. Similarly,
by giving special heed to the sensations arising in connection with the
condition of the skin at any part, we may amuse ourselves with the
strangest fancies as to what is going on in these regions.

Again, when any object of visual perception is indistinct or indefinite
in form, there is plainly an opening for this capricious play of fancy
in transforming the actual. This is illustrated in the well-known
pastime of discovering familiar forms, such as those of the human head
and animals, in distant rocks and clouds, and of seeing pictures in the
fire, and so on. The indistinct and indefinite shapes of the masses of
rock, cloud, or glowing coal, offer an excellent field for creative
fancy, and a person of lively imagination will discover endless forms in
what, to an unimaginative eye, is a formless waste. Johannes Müller
relates that, when a child, he used to spend hours in discovering the
outlines of forms in the partly blackened and cracked stucco of the
house that stood opposite to his own.[50] Here it is plain that, while
experience and association are not wholly absent, but place certain wide
limits on this process of castle-building, the spontaneous activity of
the percipient mind is the great determining force.

So much as to the influence of a perfectly unfettered voluntary
attention on the determination of the stage of preperception, and,
through this, of the resulting interpretation. Let us now pass to cases
in which this direction of preperception follows not the caprice of the
moment, but the leading of some fixed predisposition in the
interpreter's mind. In these cases attention is no longer free, but
fettered, only it is now fettered rather from within than from without;
that is to say, the dominating preperception is much more the result of
an independent bent of the imagination than of some suggestion forced on
the mind by the actual impression of the moment.

_Involuntary Mental Preadjustment._

If we glance back at the examples of capricious selection just noticed,
we shall see that they are really limited not only by the character of
the impression of the time, but also by the mental habits of the
spectator. That is to say, we find that his fancy runs in certain
definite directions, and takes certain habitual forms. It has already
been observed that the percipient mind has very different attitudes with
respect to various kinds of impression. Towards some it holds itself at
a distance, while towards others it at once bears itself familiarly; the
former are such as answer to its previous habit and bent of imagination,
the latter such as do not so answer.

This bent of the interpretative imagination assumes, as we have already
seen, two forms, that of a comparatively permanent disposition, and that
of a temporary state of expectation or mental preparedness. Illusion may
arise in connection with either of these forms. Let us illustrate both
varieties, beginning with those which are due to a lasting mental

It is impossible here to specify all the causes of illusion residing in
organized tendencies of the mind. The whole past mental life, with its
particular shade of experience, its ruling emotions, and its habitual
direction of fancy, serves to give a particular colour to new
impressions, and so to favour illusion. There is a "personal equation"
in perception as in belief--an amount of erroneous deviation from the
common average view of external things, which is the outcome of
individual temperament and habits of mind. Thus, a naturally timid man
will be in general disposed to see ugly and fearful objects where a
perfectly unbiased mind perceives nothing of the kind; and the forms
which these objects of dread will assume are determined by the character
of his past experience, and by the customary direction of his

In perfectly healthy states of mind this influence of temperament and
mental habit on the perception of external objects is, of course, very
limited; it shows itself more distinctly, as we shall see, in modifying
the estimate of things in relation to the æsthetic and other feelings.
This applies to the mythical poetical way of looking at nature--a part
of our subject to which we shall have to return later on.

Passing now from the effect of such permanent dispositions, let us look
at the more striking results of temporary expectancy of mind.

When touching on the influence of such a temporary mental attitude in
the process of correct perception, I remarked that this readiness of
mind might assume an indefinite or a definite form. We will examine the
effect of each kind in the production of illusion.

_Action of Sub-Expectation._

First of all, then, our minds may at the particular moment be disposed
to entertain any one of a vaguely circumscribed group of images. Thus,
to return to the example already referred to, when in Italy, we are in a
state of readiness to frame any of the images that we have learnt to
associate with this country. We may not be distinctly anticipating any
one kind of object, but are nevertheless in a condition of
_sub-expectation_ with reference to a large number of objects.
Accordingly, when an impression occurs which answers only very roughly
to one of the associated images, there is a tendency to superimpose the
image on the impression. In this way illusion arises. Thus, a man, when
strolling in a cathedral, will be apt to take any kind of faint hollow
sound for the soft tones of an organ.

The disposition to anticipate fact and reality in this way will be all
the stronger if, as usually happens, the mental images thus lying ready
for use have an emotional colouring. Emotion is the great disturber of
all intellectual operations. It effects marvellous things, as we shall
presently see, in the region of illusory belief, and its influence is
very marked in the seemingly cooler region of external perception. The
effect of any emotional excitement appears to be to give a preternatural
vividness and persistence to the ideas answering to it, that is to say,
the ideas which are its excitants, or which are otherwise associated
with it. Owing to this circumstance, when the mind is under the
temporary sway of any feeling, as, for example, fear, there will be a
special readiness to interpret objects by help of images congruent with
the emotion. Thus, a man under the control of fear will be ready to see
any kind of fear-inspiring object whenever there is any resemblance to
such in the things actually present to his vision. The state of awe
which the surrounding circumstances of a spiritualist _séance_ inspires
produces a general readiness of mind to perceive what is strange,
mysterious, and apparently miraculous.

It is worth noting, perhaps, that those delightful half-illusions which
imitative art seeks to produce are greatly favoured by such a temporary
attitude of the interpreting imagination. In the theatre, for example,
we are prepared for realizing the semblance of life that is to be
unfolded before us. We come knowing that what is to be performed aims at
representing a real action or actual series of events. We not improbably
work ourselves into a slightly excited state in anticipation of such a
representation. More than this, as the play progresses, the realization
of what has gone before produces a strong disposition to believe in the
reality of what is to follow. And this effect is proportionate to the
degree of coherence and continuity in the action. In this way, there is
a cumulative effect on the mind. If the action is good, the illusion, as
every play-goer knows, is most complete towards the end.

Were it not for all this mental preparation, the illusory character of
the performance would be too patent to view, and our enjoyment would
suffer. A man is often aware of this when coming into a theatre during
the progress of a piece before his mind accommodates itself to the
meaning of the play. And the same thing is recognizable in the fact that
the frequenter of the theatre has his susceptibility to histrionic
delusion increased by acquiring a habit of looking out for the meaning
of the performance. Persons who first see a play, unless they be of
exceptional imagination and have thought much about the theatre--as
Charlotte Brontë, for instance--hardly feel the illusion at all. At
least, this is true of the opera, where the departure from reality is
so striking that the impression can hardly fail to be a ludicrous one,
till the habit of taking the performance for what it is intended to be
is fully formed.[51]

A similar effect of intellectual preadjustment is observable in the
fainter degrees of illusion produced by pictorial art. Here the
undeceiving circumstances, the flat surface, the surroundings, and so
on, would sometimes be quite sufficient to prevent the least degree of
illusion, were it not that the spectator comes prepared to see a
representation of some real object. This is our state of mind when we
enter a picture gallery or approach what we recognize as a picture on
the wall of a room. A savage would not "realize" a slight sketch as soon
as one accustomed to pictorial representation, and ready to perform the
required interpretative act.[52]

So much as to the effect of an indefinite state of sub-expectation in
misleading our perceptions. Let us now glance at the results of definite
preimagination, including what are generally known as expectations.

_Effects of Vivid Expectation._

Such expectations may grow out of some present objective facts, which
serve as signs of the expected event; or they may arise by way of verbal
suggestion; or, finally, they may be due to internal spontaneous

In the first place, then, the expectations may grow out of previous
perceptions, while, nevertheless, the direction of the expectation may
be a wrong one. Here the interpreting imagination is, in a large sense,
under the control of external suggestion, though, with respect to the
particular impression that is misconstrued, it may be regarded as acting
independently and spontaneously.

Illustrations of this effect in producing illusion will easily occur to
the reader. If I happen to have heard that a particular person has been
a soldier or clergyman, I tend to see the marks of the class in this
person, and sometimes find that this process of recognition is
altogether illusory. Again, let us suppose that a person is expecting a
friend by a particular train. A passenger steps out of the train bearing
a superficial resemblance to his friend; in consequence of which he
falls into the error of false identification.

The delusions of the conjuror depend on a similar principle. The
performer tells his audience that he is about to do a certain thing, for
example, take a number of animals out of a small box which is incapable
of holding them. The hearers, intent on what has been said, vividly
represent to themselves the action described. And in this way their
attention becomes bribed, so to speak, beforehand, and fails to notice
the inconspicuous movements which would at once clear up the mystery.
Similarly with respect to the illusions which overtake people at
spiritualist _séances_. The intensity of the expectation of a particular
kind of object excludes calm attention to what really happens, and the
slightest impressions which answer to signs of the object anticipated
are instantly seized by the mind and worked up into illusory

It is to be noted that even when the impression cannot be made to tally
exactly with the expectation, the force of the latter often effects a
grotesque confusion of the perception. If, for example, a man goes into
a familiar room in the dark in order to fetch something, and for a
moment forgets the particular door by which he has entered, his definite
expectation of finding things in a certain order may blend with the
order of impressions experienced, producing for the moment a most
comical illusion as to the actual state of things.

When the degree of expectation is unusually great, it may suffice to
produce something like the counterfeit of a real sensation. This happens
when the present circumstances are powerfully suggestive of an immediate
event. The effect is all the more powerful, moreover, in those cases
where the object or event expected is interesting or exciting, since
here the mental image gains in vividness through the emotional
excitement attending it. Thus, if I am watching a train off and know
from all the signs that it is just about to start, I easily delude
myself into the conviction that it has begun to start, when it is
really still.[53] An intense degree of expectation may, in such cases,
produce something indistinguishable from an actual sensation. This
effect is seen in such common experiences as that the sight of food
makes the mouth of a hungry man water; that the appearance of a surgical
instrument produces a nascent sensation of pain; and that a threatening
movement, giving a vivid anticipation of tickling, begets a feeling
which closely approximates to the result of actual tickling.

One or two very striking instances of such imagined sensations are given
by Dr. Carpenter.[54] Here is one. An officer who superintended the
exhuming of a coffin rendered necessary through a suspicion of crime,
declared that he already experienced the odour of decomposition, though
it was afterwards found that the coffin was empty.[55]

It is, of course, often difficult to say, in such cases as these, how
far elements of actual sensation co-operate in the production of the
illusions. Thus, in the case just mentioned, the odour of the earth may
have been the starting-point in the illusion. In many cases, however, an
imaginative mind appears to be capable of transforming a vivid
expectation into a nascent stage of sensation. Thus, a mother thinking
of her sick child in an adjoining room, and keenly on the alert for its
voice, will now and again fancy she really hears it when others hear
nothing at all.

_Transition to Hallucination._

It is plain that in these cases illusion approaches to hallucination.
Imagination, instead of waiting on sensation, usurps its place and
imitates its appearance. Such a "subjective" sensation produced by a
powerful expectation might, perhaps, by a stretch of language, be
regarded as an illusion, in the narrow sense, in so far as it depends on
the suggestive force of a complete set of external circumstances; on the
other hand, it is clearly an hallucination in so far as it is the
production of the semblance of an external impression without any
external agency corresponding to this.

In the class of illusory expectations just considered the immediately
present environment still plays a part, though a much less direct part
than that observable in the first large group of illusions. We will now
pass to a second mode of illusory expectation, where imagination is
still more detached from the present surroundings.

A common instance of this kind of expectation is the so-called
"intuition," or presentiment; that something is going to happen, which
expectation has no basis in fact. It does not matter whether the
expectation has arisen by way of another's words or by way of personal
inclinations. A strong wish for a thing will, in an exalted state of
mind, beget a vivid anticipation of it. This subject will be touched on
again under the Illusions of Belief. Here I am concerned to point out
that such presentiments are fertile sources of sense-illusion. The
history of Church miracles, visions, and the like amply illustrates the
effect of a vivid anticipation in falsifying the perceptions of external

In persons of a lively imagination any recent occupation of the mind
with a certain kind of mental image may suffice to beget something
equivalent to a powerful mode of expectation. For example, we are told
by Dr. Tuke that on one occasion a lady, whose imagination had been
dwelling on the subject of drinking fountains, "thought she saw in a
road a newly erected fountain, and even distinguished an inscription
upon it, namely, 'If any man thirst, let him come unto Me, and drink.'
She afterwards found that what she had actually seen was only a few
scattered stones."[56] In many cases there seems to be a temporary
preternatural activity of the imagination in certain directions, of
which no very obvious explanation is discoverable. Thus, we sometimes
find our minds dwelling on some absent friend, without being able to
give any reason for this mental preoccupation. And in this way arise
strong temporary leanings to illusory perception. It may be said,
indeed, that all unwonted activity of the imagination, however it
arises, has as its immediate result a temporary mode of expectation,
definite or indefinite, which easily confuses our perceptions of
external things.

In proportion as this pre-existing imaginative impulse becomes more
powerful, the amount of actual impression necessary to transform the
mental image into an illusory perception becomes less; and, what is more
important, this transformation of the internal image involves a larger
and larger displacement of the actual impression of the moment. A man
whose mind is at the time strongly possessed by one kind of image, will
tend to project this outwards with hardly any regard to the actual
external circumstances.

This state of things is most completely illustrated in many of the
grosser illusions of the insane. Thus, when a patient takes any small
objects, as pebbles, for gold and silver, under the influence of the
dominant idea of being a millionaire, it is obvious that external
suggestion has very little to do with the self-deception. The confusions
into which the patient often falls with respect to the persons before
him show the same state of mind; for in many cases there is no
discoverable individual resemblance between the person actually present
and the person for whom he is taken.

It is evident that when illusion reaches this stage, it is scarcely
distinguishable from what is specially known as hallucination. As I have
remarked in setting out, illusion and hallucination shade one into the
other much too gradually for us to draw any sharp line of demarcation
between them. And here we see that hallucination differs from illusion
only in the proportion in which the causes are present. When the
internal imaginative impulse reaches a certain strength, it becomes
self-sufficient, or independent of any external impression.

This intimate relation between the extreme form of active illusion and
hallucination may be seen, too, by examining the physical conditions of
each. As I have already remarked, active illusion has for its
physiological basis a state of sub-excitation, or an exceptional
condition of irritability in the structures engaged in the act of
interpretative imagination. The greater the degree of this irritability,
the less will be the force of external stimulation needed to produce the
effect of excitation, and the more energetic will be the degree of this
excitation. Moreover, it is plain that this increase in the strength of
the excitation will involve an extension of the area of excitation till,
by-and-by, the peripheral regions of the nervous system may be involved
just as in the case of external stimulation. This accounts for the
gradual displacement of the impression of the moment by the mental
image. It follows that when the irritability reaches a certain degree,
the amount of external stimulus needed may become a vanishing quantity,
or the state of sub-excitation may of itself develop into one of full


I do not propose to go very fully into the description and explanation
of hallucinations here, since they fall to a large extent under the
category of distinctly pathological phenomena. Yet our study of
illusions would not be complete without a glance at this part of the

Hallucination, by which I mean the projection of a mental image outwards
when there is no external agency answering to it, assumes one of two
fairly distinct forms: it may present itself either as a semblance of an
external impression with the minimum amount of interpretation, or as a
counterfeit of a completely developed percept. Thus, a visual
hallucination may assume the aspect of a sensation of light or colour
which we vaguely refer to a certain region of the external world, or of
a vision of some recognizable object. All of us frequently have
incomplete visual and auditory hallucinations of the first order,
whereas the complete hallucinations of the second order are
comparatively rare. The first I shall call rudimentary, the second
developed, hallucinations.

Rudimentary hallucinations may have either a peripheral or a central
origin. They may first of all have their starting-point in those
subjective sensations which, as we have seen, are connected with certain
processes set up in the peripheral regions of the nervous system. Or,
secondly, they may originate in a certain preternatural activity of the
sensory centres, or "sensorium," in what has been called by German
physiologists an automatic excitation of the central structures, which
activity may probably diffuse itself downwards to the peripheral regions
of the nerves. Baillarger would call hallucinations of the former class
"psycho-sensorial," those of the latter class purely "psychical,"

It is often a matter of great difficulty to determine which part of the
nervous system is originally concerned in these rudimentary
hallucinations. It is probable that in normal life they are most
frequently due to peripheral disturbance. And it seems reasonable to
suppose that where the hallucination remains in this initial stage of a
very incompletely interpreted visual or auditory impression, whether in
normal or abnormal life, its real physiological source is the periphery.
For the automatic excitation of the centres would pretty certainly issue
in the semblance of some definite, familiar variety of sense-impression
which, moreover, as a part of a complex state known as a percept, would
instantly present itself as a completely formed quasi-percept. In truth,
we may pretty safely argue that if it is the centre which is directly
thrown into a state of activity, it will be thrown into the usual
complex, that is to say, _perceptional_, mode of activity.

Let us now turn to hallucinations properly so called, that is to say,
completely developed quasi-percepts. These commonly assume the form of
visual or auditory hallucinations. Like the incomplete hallucinations,
they may have their starting-point either in some disturbance in the
peripheral regions of the nervous system or in the automatic activity of
the central structures: or, to use the language of Baillarger, we may
say that they are either "psycho-sensorial" or purely "psychical." A
subjective visual sensation, arising from certain conditions in the
retina and connected portions of the optic nerve, may by chance resemble
a familiar impression, and so be at once interpreted as an effect of a
particular external object. More frequently, however, the automatic
activity of the centres must be regarded, either in part or altogether,
as the physiological cause of the phenomenon. This is clearly the case
when, on the subjective side, the hallucination answers to a preceding
energetic activity of the imagination, as in the case of the visionary
and the monomaniac. Sometimes, however, as we have seen, the
hallucinatory percept answers to previous prolonged acts of perception,
leaving a kind of reverberation in the structures concerned; and in this
case it is obviously impossible to say whether the peripheral or central
regions (if either) have most to do with the hallucination.[58]

The classifications of the causes of hallucination to be met with in the
works of pathologists, bear out the distinction just drawn. Griesinger
tells us (_op. cit._, pp. 94, 95) that the general causes of
hallucination are: (1) Local disease of the organ of sense; (2) a state
of deep exhaustion either of mind or of body; (3) morbid emotional
states, such as fear; (4) outward calm and stillness between sleeping
and waking; and (5) the action of certain poisons, as haschisch, opium,
belladonna. The first cause points pretty distinctly to a peripheral
origin, whereas the others appear to refer mainly, if not exclusively,
to central derangements. Excessive fatigue appears to predispose the
central structures to an abnormal kind of activity, and the same effect
may be brought about by emotional agitation and by the action of
poisons. The fourth case mentioned here, absence of external
stimulation, would naturally raise the nervous structures to an
exceptional pitch of excitability. Such a condition would, moreover,
prove favourable to hallucination by blurring the distinction between
mental image and actual impression.

_Hallucinations of Normal Life._

In normal life, perfect hallucinations, in the strict sense as distinct
from illusions, are comparatively rare. Fully developed persistent
hallucinations, as those of Nicolai, the Berlin bookseller, and of Mrs.
A----, the lady cited by Sir D. Brewster, in his _Letters on Natural
Magic_, point to the presence of incipient nervous disorder. In healthy
life, on the other hand, while everybody is familiar with subjective
sensations such as flying spots, phosphenes, ringing in the ears, few
fall into the error of seeing or hearing distinct recognizable objects
in the absence of all external impressions. In the lives of eminent men
we read of such phenomena as very occasional events. Malebranche, for
example, is said to have heard the voice of God calling him. Descartes
says that, after a long confinement, he was followed by an invisible
person, calling him to pursue his search for truth. Dr. Johnson narrates
that he once heard his absent mother calling him. Byron tells us that he
was sometimes visited by spectres. Goethe records that he once saw an
exact counterpart of himself coming towards him. Sir Walter Scott is
said to have seen a phantom of the dead Byron. It is possible that all
of us are liable to momentary hallucinations at times of exceptional
nervous exhaustion, though they are too fugitive to excite our

When not brought on by exhaustion or artificial means, the
hallucinations of the sane have their origin in a preternatural power of
imagination. It is well known that this power can be greatly improved by
attention and cultivation. Goethe used to exercise himself in watching
for ocular spectra, and could at will transform these subjective
sensations into definite forms, such as flowers; and Johannes Müller
found he had the same power.[59] Stories are told of portrait painters
who could summon visual images of their sitters with a vividness equal
to that of reality, and serving all the purposes of their art. Mr.
Galton's interesting inquiries into the power of "visualizing" would
appear to prove that many people can at will sport on the confines of
the phantom world of hallucination. There is good reason to think that
imaginative children tend to confuse mental images and percepts.[60]

_The Hallucinations of Insanity._

The hallucinations of the insane are but a fuller manifestation of
forces that we see at work in normal life. Their characteristic is that
they simulate the form of distinctly present objects, the existence of
which is not instantly contradicted by the actual surroundings of the
moment.[61] The hallucinations have their origin partly in subjective
sensations, which are probably connected with peripheral disturbances,
partly and principally in central derangements.[62] These include
profound emotional changes, which affect the ruling mental tone, and
exert a powerful influence on the course of the mental images. The
hallucinations of insanity are due to a projection of mental images
which have, owing to certain circumstances, gained a preternatural
persistence and vividness. Sometimes it is the images that have been
dwelt on with passionate longing before the disease, sometimes those
which have grown most habitual through the mode of daily
occupation,[63] and sometimes those connected with some incident at or
near the time of the commencement of the disease.

In mental disease, auditory hallucinations play a part no less
conspicuous than visual.[64] Patients frequently complain of having
their thoughts spoken to them, and it is not uncommon for them to
imagine that they are addressed by a number of voices at the same

These auditory hallucinations offer a good opportunity for studying the
gradual growth of centrally originating hallucinations. In the early
stages of the disease, the patient partly distinguishes his
representative from his preservative sounds. Thus, he talks of sermons
being composed to him _in his head_. He calls these "internal voices,"
or "voices of the soul." It is only when the disease gains ground and
the central irritability increases that these audible thoughts become
distinctly projected as external sounds into more or less definite
regions of the environment. And it is exceedingly curious to notice the
different directions which patients give to these sounds, referring them
now to a quarter above the head, now to a region below the floor, and so

_Range of Sense-Illusions._

And now let us glance back to see the path we have traversed. We set out
with an account of perfectly normal perception, and found, even here, in
the projection of our sensations of colour, sound, etc., into the
environment or to the extremities of the organism, something which, from
the point of view of physical science, easily wears the appearance of an
ingredient of illusion.

Waiving this, however, and taking the word illusion as commonly
understood, we find that it begins when the element of imagination no
longer answers to a present reality or external fact in any sense of
this expression. In its lowest stages illusion closely counterfeits
correct perception in the balance of the direct factor, sensation, and
the indirect factor, mental reproduction or imagination. The degree of
illusion increases in proportion as the imaginative element gains in
force relatively to the present impression; till, in the wild illusions
of the insane, the amount of actual impression becomes evanescent. When
this point is reached, the act of imagination shows itself as a purely
creative process, or an hallucination.

While we may thus trace the progress of illusion towards hallucination
by means of the gradual increase in force and extent of the imaginative,
or indirect, as opposed to the sensuous, or direct, element in
perception, we have found a second starting-point for this movement in
the mechanism of sensation, involving, as it does, the occasional
production of "subjective sensations." Such sensations constitute a
border-land between the regions of illusion in the narrow sense, and
hallucination. In their simplest and least developed form they may be
regarded, at least in the case of hearing and sight, as partly
hallucinatory; and they serve as a natural basis for the construction of
complete hallucinations, or hallucinatory percepts.

In these different ways, then, the slight, scarcely noticeable illusions
of normal life lead up to the most startling hallucinations of abnormal
life. From the two poles of the higher centres of attention and
imagination on the one side, and the lower regions of nervous action
involved in sensation on the other side, issue forces which may, under
certain circumstances, develop into full hallucinatory percepts. Thus
closely is healthy attached to morbid mental life. There seems to be no
sudden break between our most sober every-day recognitions of familiar
objects and the wildest hallucinations of the demented. As we pass from
the former to the latter, we find that there is never any abrupt
transition, never any addition of perfectly new elements, but only that
the old elements go on combining in ever new proportions.

The connection between the illusory side of our life and insanity may be
seen in another way. All illusion has as its negative condition an
interruption of the higher intellectual processes, the due control of
our mental representations by reflection and reason. In the case of
passive illusions, the error arises from our inability to subordinate
the suggestion made by some feature of the present impression to the
result of a fuller inspection of the object before us, or of a wider
reflection on the past. In other words, our minds are dominated by the
partial and the particular, to the exclusion of the total or the
general. In active illusions, again, the powers of judgment and
reflection, including those of calm perception itself, temporarily
vacate their throne in favour of imagination. And this same suspension
of the higher intellectual functions, the stupefaction of judgment and
reflection made more complete and permanent, is just what characterizes

We may, perhaps, express this point of connection between the illusions
of normal life and insanity by help of a physiological hypothesis. If
the nervous system has been slowly built up, during the course of human
history, into its present complex form, it follows that those nervous
structures and connections which have to do with the higher intellectual
processes, or which represent the larger and more general relations of
our experience, have been most recently evolved. Consequently, they
would be the least deeply organized, and so the least stable; that is
to say, the most liable to be thrown _hors de combat_. This is what
happens temporarily in the case of the sane, when the mind is held fast
by an illusion. And, in states of insanity, we see the process of
nervous dissolution beginning with these same nervous structures, and so
taking the reverse order of the process of evolution.[67] And thus, we
may say that throughout the mental life of the most sane of us, these
higher and more delicately balanced structures are constantly in danger
of being reduced to that state of inefficiency, which in its full
manifestation is mental disease.

Does this way of putting the subject seem alarming? Is it an appalling
thought that our normal mental life is thus intimately related to
insanity, and graduates away into it by such fine transitions? A
moment's reflection will show that the case is not so bad as it seems.
It is well to remind ourselves that the brain is a delicately adjusted
organ, which very easily gets disturbed, and that the best of us are
liable to become the victims of absurd illusion if we habitually allow
our imaginations to be overheated, whether by furious passion or by
excessive indulgence in the pleasures of day-dreaming, or in the
intoxicating mysteries of spiritualist _séances_. But if we take care to
keep our heads cool and avoid unhealthy degrees of mental excitement, we
need not be very anxious on the ground of our liability to this kind of
error. As I have tried to show, our most frequent illusions are
necessarily connected with something exceptional, either in the
organism or in the environment. That is to say, it is of the nature of
illusion in healthy conditions of body and mind to be something very
occasional and relatively unimportant. Our perceptions may be regarded
as the reaction of the mind on the impressions borne in from the
external world, or as a process of adjustment of internal mental
relations to external physical relations. If this process is, in the
main, a right one, we need not greatly trouble, because it is not
invariably so. We should accept the occasional failure of the
intellectual mechanism as an inseparable accompaniment of its general

To this it must be added that many of the illusions described above can
hardly be called cases of non-adaptation at all, since they have no
relation to the practical needs of life, and consequently are, in a
general way, unattended to. In other cases, again, namely, where the
precise nature of a present sensation, being practically an unimportant
matter, is usually unattended to, as in the instantaneous recognition of
objects by the eye under changes of illumination, etc., the illusion is
rather a part of the process of adaptation, since it is much more
important to recognize the permanent object signified by the sensation
than the precise nature of the present sensational "sign" itself.

Finally, it should never be forgotten that in normal states of mind
there is always the possibility of rectifying an illusion. What
distinguishes abnormal from normal mental life is the persistent
occupation of the mind by certain ideas, so that there is no room for
the salutary corrective effect of reflection on the actual impression
of the moment, by which we are wont to "orientate," or take our bearings
as to the position of things about us. In sleep, and in certain
artificially produced states, much the same thing presents itself.
Images become realities just because they are not instantly recognized
as such by a reference to the actual surroundings of the moment. But in
normal waking life this power of correction remains with us. We may not
exercise it, it is true, and thus the illusion will tend to become more
or less persistent and recurring; for the same law applies to true and
to false perception: repetition makes the process easier. But if we only
choose to exert ourselves, we can always keep our illusions in a nascent
or imperfectly developed stage. This applies not only to those
half-illusions into which we voluntarily fall, but also to the more
irresistible passive illusions, and those arising from an over-excited
imagination. Even persons subject to hallucinations, like Nicolai of
Berlin, learn to recognize the unreal character of these phantasms. On
this point the following bit of autobiography from the pen of Coleridge
throws an interesting light. "A lady (he writes) once asked me if I
believed in ghosts and apparitions. I answered with truth and
simplicity, No, madam, I have seen far too many myself."[68] However
irresistible our sense-illusions may be, so long as we are under the
sway of particular impressions or mental images, we can, when resolved
to do so, undeceive ourselves by carefully attending to the actual
state of things about us. And in many cases, when once the correction is
made, the illusion seems an impossibility. By no effort of imagination
are we able to throw ourselves back into the illusory mental condition.
So long as this power of dispelling the illusion remains with us, we
need not be alarmed at the number and variety of the momentary
misapprehensions to which we are liable.



The phenomena of dreams may well seem at first sight to form a world of
their own, having no discoverable links of connection with the other
facts of human experience. First of all, there is the mystery of sleep,
which quietly shuts all the avenues of sense and so isolates the mind
from contact with the world outside. To gaze at the motionless face of a
sleeper temporarily rapt from the life of sight, sound, and
movement--which, being common to all, binds us together in mutual
recognition and social action--has always something awe-inspiring. This
external inaction, this torpor of sense and muscle, how unlike to the
familiar waking life, with its quick responsiveness and its overflowing
energy! And then, if we look at dreams from the inside, we seem to find
but the reverse face of the mystery. How inexpressibly strange does the
late night-dream seem to a person on waking! He feels he has been seeing
and hearing things no less real than those of waking life; but things
which belong to an unfamiliar world, an order of sights and a sequence
of events quite unlike those of waking experience; and he asks himself
in his perplexity where that once-visited region really lies, or by what
magic power it was suddenly and for a moment created for his vision. In
truth, the very name of dream suggests something remote and mysterious,
and when we want to characterize some impression or scene which by its
passing strangeness filled us with wonder, we naturally call it

_Theories of Dreams._

The earliest theories respecting dreams illustrate very clearly this
perception of the remoteness of dream-life from waking experience. By
the simple mind of primitive man this dream-world is regarded as similar
in its nature or structure to our common world, only lying remote from
this. The savage conceives that when he falls asleep, his second self
leaves his familiar body and journeys forth to unfamiliar regions, where
it meets the departed second selves of his dead ancestors, and so on.
From this point of view, the experience of the night, though equal in
reality to that of the day, is passed in a wholly disconnected

A second and more thoughtful view of dreams, marking a higher grade of
intellectual culture, is that these visions of the night are symbolic
pictures unfolded to the inner eye of the soul by some supernatural
being. The dream-experience is now, in a sense, less real than it was
before, since the phantasms that wear the guise of objective realities
are simply images spread out to the spirit's gaze, or the direct
utterance of a divine message. Still, this mysterious contact of the
mind with the supernatural is regarded as a fact, and so the dream
assumes the appearance of a higher order of experience. Its one point of
attachment to the experience of waking life lies in its symbolic
function; for the common form which this supernatural view assumes is
that the dream is a dim prevision of coming events. Artemidorus, the
great authority on dream interpretation (_oneirocritics_) for the
ancient world, actually defines a dream as "a motion or fiction of the
soul in a diverse form signifying either good or evil to come;" and even
a logician like Porphyry ascribes dreams to the influence of a good
demon, who thereby warns us of the evils which another and bad demon is
preparing for us. The same mode of viewing dreams is quite common
to-day, and many who pride themselves on a certain intellectual culture,
and who imagine themselves to be free from the weakness of superstition,
are apt to talk of dreams as of something mysterious, if not distinctly
ominous. Nor is it surprising that phenomena which at first sight look
so wild and lawless, should still pass for miraculous interruptions of
the natural order of events.[70]

Yet, in spite of this obvious and impressive element of the mysterious
in dream-life, the scientific impulse to illuminate the less known by
the better known has long since begun to play on this obscure subject.
Even in the ancient world a writer might here and there be found, like
Democritus or Aristotle, who was bold enough to put forward a natural
and physical explanation of dreams. But it has been the work of modern
science to provide something like an approximate solution of the
problem. The careful study of mental life in its intimate union with
bodily operations, and the comparison of dream-combinations with other
products of the imagination, normal as well as morbid, have gradually
helped to dissolve a good part of the mystery which once hung like an
opaque mist about the subject. In this way, our dream-operations have
been found to have a much closer connection with our waking experiences
than could be supposed on a superficial view. The materials of our
dreams are seen, when closely examined, to be drawn from our waking
experience. Our waking consciousness acts in numberless ways on our
dreams, and these again in unsuspected ways influence our waking mental
life.[71] Not only so, it is found that the quaint chaotic play of
images in dreams illustrates mental processes and laws which are
distinctly observable in waking thought. Thus, for example, the apparent
objective reality of these visions has been accounted for, without the
need of resorting to any supernatural agency, in the light of a vast
assemblage of facts gathered from the by-ways, so to speak, of waking
mental life. I need hardly add that I refer to the illusions of sense
dealt with in the foregoing chapters.

Dreams are to a large extent the semblance of external perceptions.
Other psychical phenomena, as self-reflection, emotional activity, and
so on, appear in dream-life, but they do so in close connection with
these quasi-perceptions. The name "vision," given by old writers to
dreams, sufficiently points out this close affinity of the mental
phenomena to sense-perception; and so far as science is concerned, they
must be regarded as a peculiar variety of sense-illusion. Hence the
appropriateness of studying them in close connection with the illusions
of perception of the waking state. Though marked off by the presence of
very exceptional physiological conditions, they are largely intelligible
by help of these physiological and psychological principles which we
have just been considering.

_The State of Sleep._

The physiological explanation of dreams must, it is plain, set out with
an account of the condition of the organism known as sleep. While there
is here much that is uncertain, there are some things which are fairly
well known. Recent physiological observation has gone to prove that
during sleep all the activities of the organism are appreciably lowered.
Thus, for example, according to Testa, the pulse falls by about
one-fifth. This lowering of the organic functions appears, under
ordinary circumstances, to increase towards midnight, after which there
is a gradual rising.

The nervous system shares in this general depression of the vital
activities. The circulation being slower, the process of reparation and
nutrition of the nerves is retarded, and so their degree of excitability
diminished. This is clearly seen in the condition of the peripheral
regions of the nervous system, including the sense-organs, which appear
to be but very slightly acted on by their customary stimuli.

The nervous centres must participate in this lethargy of the system. In
other words, the activity of the central substance is lowered, and the
result of this is plainly seen in what is usually thought of as the
characteristic feature of sleep, namely, a transition from vigorous
mental activity or intense and clear consciousness, to comparative
inactivity or faint and obscure consciousness. The cause of this
condition of the centres is supposed to be the same as that of the
torpidity of all the other organs in sleep, namely, the retardation of
the circulation. But, though there is no doubt as to this, the question
of the proximate physiological conditions of sleep is still far from
being settled. Whether during sleep the blood-vessels of the brain are
fuller or less full than during waking, is still a moot point. Also the
qualitative condition of the blood in the cerebral vessels is still a
matter of discussion.[72]

Since the effect of sleep is to lower central activity, the question
naturally occurs whether the nervous centres are ever rendered inactive
to such an extent as to interrupt the continuity of our conscious life.
This question has been discussed from the point of view of the
metaphysician, of the psychologist, and of the physiologist, and in no
case is perfect unanimity to be found. The metaphysical question,
whether the soul as a spiritual substance is capable of being wholly
inactive, or whether it is not in what seem the moments of profoundest
unconsciousness partially awake--the question so warmly discussed by the
Cartesians, Leibnitz, etc.--need not detain us here.

Of more interest to us are the psychological and the physiological
discussions. The former seeks to settle the question by help of
introspection and memory. On the one side, it is urged against the
theory of unbroken mental activity, that we remember so little of the
lowered consciousness of sleep.[73] To this it is replied that our
forgetfulness of the contents of dream-consciousness, even if this were
unbroken, would be fully accounted for by the great dissimilarity
between dreaming and waking mental life. It is urged, moreover, on this
side that a sudden rousing of a man from sleep always discovers him in
the act of dreaming, and that this goes to prove the uniform connection
of dreaming and sleeping. This argument, again, may be met by the
assertion that our sense of the duration of our dreams is found to be
grossly erroneous; that, owing to the rapid succession of the images,
the _realization_ of which would involve a long duration, we enormously
exaggerate the length of dreams in retrospection.[74] From this it is
argued that the dream which is recalled on our being suddenly awakened
may have had its whole course during the transition state of waking.

Again, the fact that a man may resolve, on going to sleep, to wake at a
certain hour, has often been cited in proof of the persistence of a
degree of mental activity even in perfectly sound sleep. The force of
this consideration, however, has been explained away by saying that the
anticipation of rising at an unusual hour necessarily produces a slight
amount of mental disquietude, which is quite sufficient to prevent sound
sleep, and therefore to expose the sleeper to the rousing action of
faint external stimuli.

While the purely psychological method is thus wholly inadequate to solve
the question, physiological reasoning appears also to be not perfectly
conclusive. Many physiologists, not unnaturally desirous of upsetting
what they regard as a gratuitous metaphysical hypothesis, have
pronounced in favour of an absolutely dreamless or unconscious sleep.
From the physiological point of view, there is no mystery in a totally
suspended mental activity. On the other hand, there is much to be said
on the opposite side, and perhaps it may be contended that the purely
physiological evidence rather points to the conclusion that central
activity, however diminished during sleep, always retains a minimum
degree of intensity. At least, one would be disposed to argue in this
way from the analogy of the condition of the other functions of the
organism during sleep. Possibly this modicum of positive evidence may
more than outweigh any slight presumption against the doctrine of
unbroken mental activity drawn from the negative circumstance that we
remember so little of our dream-life.[75]

Such being the state of physiological knowledge respecting the
immediate conditions of sleep, we cannot look for any certain
information on the nature of that residual mode of cerebral activity
which manifests itself subjectively in dreams. It is evident, indeed,
that this question can only be fully answered when the condition of the
brain as a whole during sleep is understood. Meanwhile we must be
content with vague hypotheses.

It may be said, for one thing, that during sleep the nervous substance
as a whole is less irritable than during waking hours. That is to say, a
greater amount of stimulus is needed to produce any conscious
result.[76] This appears plainly enough in the case of the peripheral
sense-organs. Although these are not, as it is often supposed, wholly
inactive during sleep, they certainly require a more potent external
stimulus to rouse them to action. And what applies to the peripheral
regions applies to the centres. In truth, it is clearly impossible to
distinguish between the diminished irritability of the peripheral and
that of the central structures.

At first sight it seems contradictory to the above to say that stimuli
which have little effect on the centres of consciousness during waking
life produce an appreciable result in sleep. Nevertheless, it will be
found that this is the case. Thus organic processes which scarcely make
themselves known to the mind in a waking state, may be shown to be the
originators of many of our dreams. This fact can only be explained on
the physical side by saying that the special cerebral activities
engaged in an act of attention are greatly liberated during sleep by the
comparative quiescence of the external senses. These activities, by
co-operating with the faint results of the stimuli coming from the
internal organs, serve very materially to increase their effect.

Finally, it is to be observed that, while the centres thus respond with
diminished energy to peripheral stimuli, external and internal, they
undergo a direct, or "automatic," mode of excitation, being roused into
activity independently of an incoming nervous impulse. This automatic
stimulation has been plausibly referred to the action of the products of
decomposition accumulating in the cerebral blood-vessels.[77] It is
possible that there is something in the nature of this stimulation to
account for the force and vividness of its conscious results, that is to
say, of dreams.

_The Dream State._

Let us now turn to the psychic side of these conditions, that is to say,
to the general character of the mental states known as dreams. It is
plain that the closing of the avenues of the external senses, which is
the accompaniment of sleep, will make an immense difference in the
mental events of the time. Instead of drawing its knowledge from
without, noting its bearings in relation to the environment, the mind
will now be given over to the play of internal imagination. The activity
of fancy will, it is plain, be unrestricted by collision with external
fact. The internal mental life will expand in free picturesque

To say that in sleep the mind is given over to its own imaginings, is to
say that the mental life in these circumstances will reflect the
individual temperament and mental history. For the play of imagination
at any time follows the lines of our past experience more closely than
would at first appear, and being coloured with emotion, will reflect the
predominant emotional impulses of the individual mind. Hence the saying
of Heraclitus, that, while in waking we all have a common world, in
sleep we have each a world of our own.

This play of imagination in sleep is furthered by the peculiar attitude
of attention. When asleep the voluntary guidance of attention ceases;
its direction is to a large extent determined by the contents of the
mind at the moment. Instead of holding the images and ideas, and
combining them according to some rational end, the attention relaxes its
energies and succumbs to the force of imagination. And thus, in sleep,
just as in the condition of reverie or day-dreaming, there is an
abandonment of the fancy to its own wild ways.

It follows that the dream-state will not appear to the mind as one of
fancy, but as one of actual perception, and of contact with present
reality. Dreams are clearly illusory, and, unlike the illusions of
waking life, are complete and persistent.[78] And the reason of this
ought now to be clear. First of all, the mind during sleep wants what M.
Taine calls the corrective of a present sensation. When awake under
ordinary circumstances, any momentary illusion is at once set right by a
new act of orientation. The superior vividness of the external
impression cannot leave us in any doubt, when calm and self-possessed,
whether our mental images answer to present realities or not. On the
other hand, when asleep, this reference to a fixed objective standard is
clearly impossible. Secondly, we may fairly argue that the mental images
of sleep approximate in character to external impressions. This they do
to some extent in point of intensity, for, in spite of the diminished
excitability of the centres, the mode of stimulation which occurs in
sleep may, as I have hinted, involve an energetic cerebral action. And,
however this be, it is plain that the image will gain a preternatural
force through the greatly narrowed range of attention. When the mind of
the sleeper is wholly possessed by an image or group of images, and the
attention kept tied down to these, there is a maximum reinforcement of
the images. But this is not all. When the attention is thus held captive
by the image, it approximates in character to an external impression in
another way. In our waking state, when our powers of volition are
intact, the external impression is characterized by its fixity or its
obdurate resistance to our wishes. On the other hand, the mental image
is fluent, accommodating, and disappears and reappears according to the
direction of our volitions. In sleep, through the suspension of the
higher voluntary power of attention, the mental image seems to lord it
over our minds just as the actual impression of waking life.

This much may suffice, perhaps, by way of a general description of the
sleeping and dreaming state. Other points will make themselves known
after we have studied the contents and structure of dreams in detail.

Dreams are commonly classified (_e.g._ by Wundt) with hallucinations,
and this rightly, since, as their common appellation of "vision"
suggests, they are for the most part the semblance of percepts in the
absence of external impressions. At the same time, recent research goes
to show that in many dreams something answering to the "external
impression" in waking perception is the starting-point. Consequently, in
order to be as accurate as possible, I shall divide dreams into
illusions (in the narrow sense) and hallucinations.


By dream-illusions I mean those dreams which set out from some
peripheral nervous stimulation, internal or external. That the organic
processes of digestion, respiration, etc., act as stimuli to the centres
in sleep is well known. Thus, David Hartley assigns as the second great
source of dreams "states of the body."[79] But it is not so well known
to what an extent our dreams may be influenced by stimuli acting on the
exterior sense-organs. Let us first glance at the action of such
external stimuli.

_Action of External Stimuli._

During sleep the eyes are closed, and consequently the action of
external light on the retina impeded. Yet it is found that even under
these circumstances any very bright light suddenly introduced is capable
of stimulating the optic fibres, and of affecting consciousness. The
most common form of this is the effect of bright moonlight, and of the
early sun's rays. Krauss tells a funny story of his having once, when
twenty-six years old, caught himself, on waking, in the act of
stretching out his arms towards what his dream-fancy had pictured as the
image of his mistress. When fully awake, this image resolved itself into
the full moon.[80] It is not improbable, as Radestock remarks, that the
rays of the sun or moon are answerable for many of the dreams of
celestial glory which persons of a highly religious temperament are said
to experience.

External sounds, when not sufficient to rouse the sleeper, easily
incorporate themselves into his dreams. The ticking of a watch, the
stroke of a clock, the hum of an insect, the song of a bird, the patter
of rain, are common stimuli to the dream-phantasy. M. Alf. Maury tells
us, in his interesting account of the series of experiments to which he
submitted himself in order to ascertain the result of external
stimulation on the mind during sleep, that when a pair of tweezers was
made to vibrate near his ear, he dreamt of bells, the tocsin, and the
events of June, 1848.[81] Most of us, probably, have gone through the
experience of impolitely falling asleep when some one was reading to us,
and of having dream-images suggested by the sounds that were still
indistinctly heard. Scherner gives an amusing case of a youth who was
permitted to whisper his name into the ear of his obdurate mistress,
the consequence of which was that the lady contracted a habit of
dreaming about him, which led to a felicitous change of feeling on her

The two lower senses, smell and taste, seem to play a less-important
part in the production of dream-illusions. Radestock says that the odour
of flowers in a room easily leads to visual images of hot-houses,
perfumery shops, and so on; and it is probable that the contents of the
mouth may occasionally act as a stimulus to the organ of taste, and so
give rise to corresponding dreams. As Radestock observes, these lower
sensations do not commonly make known their quality to the sleeper's
mind. They become transformed at once into visual, instead of into
olfactory or gustatory percepts. That is to say, the dreamer does not
imagine himself smelling or tasting, but seeing an object.

The contact of objects with the tactual organ is one of the best
recognized causes of dreams. M. Maury found that when his lips were
tickled, his dream-fancy interpreted the impression as of a pitch
plaster being torn off his face. An unusual pressure on any part of the
body, as, for example, from contact with a fellow-sleeper, is known to
give rise to a well-marked variety of dream. Our own limbs may even
appear as foreign bodies to our dream-imagination, when through pressure
they become partly paralyzed. Thus, on one occasion, I awoke from a
miserable dream, in which I felt sure I was grasping somebody's hand in
bed, and I was racked by terrifying conjectures as to who it might be.
When fully awake, I discovered that I had been lying on my right side,
and clasping the wrist of the right arm (which had been rendered
insensible by the pressure of the body) with the left hand.

In close connection with these stimuli of pressure are those of muscular
movement, whether unimpeded or impeded. We need not enter into the
difficult question how far the "muscular sense" is connected with the
activity of the motor nerves, and how far with sensory fibres attached
to the muscular or the adjacent tissues. Suffice it to say that an
actual movement, a resistance to an attempted movement, or a mere
disposition to movement, whether consequent on a surplus of motor energy
or on a sensation of discomfort or fatigue in the part to be moved,
somehow or other makes itself known to our minds, even when we are
deprived of the assistance of vision. And these feelings of movement,
impeded or unimpeded, are common initial impulses in our
dream-experiences. It is quite a mistake to suppose that dreams are
built up out of the purely passive sensations of sight and hearing. A
close observation will show that in nearly every dream we imagine
ourselves either moving among the objects we perceive or striving to
move when some weighty obstacle obstructs us. All of us are familiar
with the common forms of nightmare, in which we strive hopelessly to
flee from some menacing evil, and this dream-experience, it may be
presumed, frequently comes from a feeling of strain in the muscles, due
to an awkward disposition of the limbs during sleep. The common
dream-illusion of falling down a vast abyss is plausibly referred by
Wundt to an involuntary extension of the foot of the sleeper.

_Action of Internal Stimuli._

Let us now pass from the action of stimuli lying outside the organism,
to that of stimuli lying within the peripheral regions of the
sense-organs. I have already spoken of the influence of subjective
sensations of sight, hearing, etc., on the illusions of waking life, and
it is now to be added that these sensations play an important part in
our dream-life. Johannes Müller lays great prominence on the part taken
by ocular spectra in the production of dreams. As he observes, the
apparent rays of light, light-patches, mists of light, and so on, due to
changes of blood-pressure in the retina, only manifest themselves
clearly when the eyes are closed and the more powerful effect of the
external stimulus cut off. These subjective spectra come into prominence
in the sleepy condition, giving rise to what M. Maury calls
"hallucinations hypnagogiques," and which he regards (after Gruithuisen)
as the chaos out of which the dream-cosmos is evolved.[83] They are
pretty certainly the starting-point in those picturesque dreams in which
figure a number of bright objects, such as beautiful birds, butterflies,
flowers, or angels.

That the visual images of our sleep do often involve the peripheral
regions of the organ of sight, seems to be proved by the singular fact
that they sometimes persist after waking. Spinoza and Jean Paul Richter
both experienced this survival of dream-images. Still more pertinent is
the fact that the effects of retinal fatigue are producible by
dream-images. The physiologist Gruithuisen had a dream, in which the
principal feature was a violet flame, and which left behind it, _after
waking_, for an appreciable duration, a complementary image of a yellow

Subjective auditory sensations appear to be much less frequent causes of
dream-illusions than corresponding visual sensations. Yet the rushing,
roaring sound caused by the circulation of the blood in the ear is,
probably, a not uncommon starting-point in dreams. With respect to
subjective sensations of smell and taste, there is little to be said. On
the other hand, subjective sensations due to varying conditions in the
skin are a very frequent exciting cause of dreams. Variations in the
state of tension of the skin, brought about by alteration of position,
changes in the character of the circulation, the irradiation of heat to
the skin or the loss of the same, chemical changes,--these are known to
give rise to a number of familiar sensations, including those of
tickling, itching, burning, creeping, and so on; and the effects of
these sensations are distinctly traceable in our dreams. For example,
the exposure of a part of the body through a loss of the bed-clothes is
a frequent excitant of distressing dreams. A cold foot suggests that the
sleeper is walking over snow or ice. On the other hand, if the cold foot
happens to touch a warm part of the body, the dream-fancy constructs
images of walking on burning lava, and so on.

These sensations of the skin naturally conduct us to the organic
sensations as a whole; that is to say, the feelings connected with the
varying condition of the bodily organs. These include the feelings which
arise in connection with the processes of digestion, respiration, and
circulation, and the condition of various organs according to their
state of nutrition, etc. During our waking life these organic feelings
coalesce for the most part, forming as the "vital sense" an obscure
background for our clear discriminative consciousness, and only come
forward into this region when very exceptional in character, as when
respiration or digestion is impeded, or when we make a special effort of
attention to single them out.[85] When we are asleep, however, and the
avenues of external perception are closed, they assume greater
prominence and distinctness. The centres, no longer called upon to react
on stimuli coming from without the organism, are free to react on
stimuli coming from its hidden recesses. So important a part, indeed, do
these organic feelings take in the dream-drama, that some writers are
disposed to regard them as the great, if not the exclusive, cause of
dreams. Thus, Schopenhauer held that the excitants of dreams are
impressions received from the internal regions of the organism through
the sympathetic nervous system.[86]

It is hardly necessary, perhaps, to give many illustrations of the
effect of such organic sensations on our dreams. Among the most common
provocatives of dreams are sensations connected with a difficulty in
breathing, due to the closeness of the air or to the pressure of the
bed-clothes on the mouth. J. Börner investigated the influence of these
circumstances by covering with the bed-clothes the mouth and a part of
the nostrils of persons who were sound asleep. This was followed by a
protraction of the act of breathing, a reddening of the face, efforts to
throw off the clothes, etc. On being roused, the sleeper testified that
he had experienced a nightmare, in which a horrid animal seemed to be
weighing him down.[87] Irregularity of the heart's action is also a
frequent cause of dreams. It is not improbable that the familiar
dream-experience of flying arises from disturbances of the respiratory
and circulatory movements.

Again, the effects of indigestion, and more particularly stomachic
derangement, on dreams are too well known to require illustration. It
may be enough to allude to the famous dream which Hood traces to an
excessive indulgence at supper. It is known that the varying condition
of the organs of secretion influences our dream-fancy in a number of

Finally, it is to be observed that an injury done to any part of the
organism is apt to give rise to appropriate dream-images. In this way,
very slight disturbances which would hardly affect waking consciousness
may make themselves felt during sleep. Thus, for example, an incipient
toothache has been known to suggest that the teeth are being

It is worth observing that the interpretation of these various orders of
sensations by the imagination of the dreamer takes very different forms
according to the person's character, previous experience, ruling
emotions, and so on. This is what is meant by saying that during sleep
every man has a world of his own, whereas, when awake, he shares in the
common world of perception.


It is to be noticed, further, that this interpretation of sensation
during sleep is uniformly a process of exaggeration.[89] The exciting
causes of the feeling of discomfort, for example, are always absurdly
magnified. The reason of this seems to be that, owing to the condition
of the mind during sleep, the nature of the sensation is not clearly
recognizable. Even in the case of familiar external impressions, such as
the sound of the striking of a clock, there appears to be wanting that
simple process of reaction by which, in a waking condition of the
attention, a sense-impression is instantly discriminated and classed. In
sleep, as in the artificially induced hypnotic condition, the slighter
differences of quality among sensations are not clearly recognized. The
activity of the higher centres, which are concerned in the finer
processes of discrimination and classification, being greatly reduced,
the impression may be said to come before consciousness as something
novel and unfamiliar. And just as we saw that in waking life novel
sensations agitate the mind, and so lead to an exaggerated mode of
interpretation; so here we see that what is unfamiliar disturbs the
mind, rendering it incapable of calm attention and just interpretation.

This failure to recognize the real nature of an impression is seen most
conspicuously in the case of the organic sensations. As I have remarked,
these constitute for the most part, in waking life, an undiscriminated
mass of obscure feeling, of which we are only conscious as the mental
tone of the hour. And in the few instances in which we do attend to them
separately, whether through their exceptional intensity or in
consequence of an extraordinary effort of discriminative attention, we
can only be said to perceive them, that is, recognize their local
origin, very vaguely. Hence, when asleep, these sensations get very
oddly misinterpreted.

The localization of a bodily sensation in waking life means the
combination of a tactual and a visual image with the sensation. Thus, my
recognition of a twinge of toothache as coming from a certain tooth,
involves representations of the active and passive sensations which
touching and looking at the tooth would yield me. That is to say, the
feeling instantly calls up a compound mental image exactly answering to
a visual percept. This holds good in dream-interpretation too; the
interpretation is effected by means of a visual image. But since the
feeling is only very vaguely recognized, this visual image does not
answer to the bodily part concerned. Instead of this, the fancy of the
dreamer constructs some visual image which bears a vague resemblance to
the proper one, and is generally, if not always, an exaggeration of this
in point of extensive magnitude, etc. For example, a sensation arising
from pressure on the bladder, being dimly connected with the presence of
a fluid, calls up an image of a flood, and so on.

This mode of dream-interpretation has by some writers been erected into
the typical mode, under the name of dream-symbolism. Thus Scherner, in
his interesting though somewhat fanciful work, _Das Leben des Traumes_,
contends that the various regions of the body regularly disclose
themselves to the dream-fancy under the symbol of a building or group of
buildings; a pain in the head calling up, for example, the image of
spiders on the ceiling, intestinal sensations exciting an image of a
narrow alley, and so on. Such theories are clearly an exaggeration of
the fact that the localization of our bodily sensations during sleep is
necessarily imperfect.[90]

In many cases the image called up bears on its objective side no
discoverable resemblance to that of the bodily region or the exciting
cause of the sensation. Here the explanation must be looked for in the
subjective side of the sensation and mental image, that is to say, in
their emotional quality, as pleasurable or painful, distressing,
quieting, etc. It is to be observed, indeed, that in natural sleep, as
in the condition known as hypnotism, while differences of specific
quality in the sense-impressions are lost, the broad difference of the
pleasurable and the painful is never lost. It is, in fact, the
subjective emotional side of the sensation that uniformly forces itself
into consciousness. This being so, it follows that, speaking generally,
the sensations of sleep, both external and internal, or organic, will be
interpreted by what G.H. Lewes has called "an analogy of feeling;" that
is to say, by means of a mental image having some kindred emotional
character or colouring.

Now, the analogy between the higher emotional and the bodily states is a
very close one. A sensation of obstruction in breathing has its exact
analogue in a state of mental embarrassment, a sensation of itching its
counterpart in mental impatience, and so on. And since these emotional
experiences are deeper and fuller than the sensations, the tendency to
exaggerate the nature and causes of these last would naturally lead to
an interpretation of them by help of these experiences. In addition to
this, the predominance of visual imagery in sleep would aid this
transformation of a bodily sensation into an emotional experience, since
visual perceptions have, as their accompaniments of pleasure and pain,
not sensations, but emotions.[91]

Since in this vague interpretation of bodily sensation the actual
impression is obscured, and not taken up as an integral part into the
percept, it is evident that we cannot, strictly speaking, call the
process an imitation of an act of perception, that is to say, an
illusion. And since, moreover, the visual image by which the sensation
is thus displaced appears as a present object, it would, of course, be
allowable to speak of this as an hallucination. This substitution of a
more or less analogous visual image for that appropriate to the
sensation forms, indeed, a transition from dream-illusion, properly so
called, to dream-hallucination.


On the physical side, these hallucinations answer to cerebral
excitations which are central or automatic, not depending on movements
transmitted from the periphery of the nervous system. Of these
stimulations some appear to be direct, and due to unknown influences
exerted by the state of nutrition of the cerebral elements, or the
action of the contents of the blood-vessels on these elements.

_Effects of Direct Central Stimulation._

That such action does prompt a large number of dream-images may be
regarded as fairly certain. First of all, it seems impossible to account
for all the images of dream-fancy as secondary phenomena connected by
links of association with the foregoing classes of sensation. However
fine and invisible many of the threads which hold together our ideas may
be, they will hardly explain the profusion and picturesque variety of
dream-imagery. Secondly, we are able in certain cases to infer with a
fair amount of certainty that a dream-image is due to such central
stimulation. The common occurrence that we dream of the more stirring
events, the anxieties and enjoyments of the preceding day, appears to
show that when the cerebral elements are predisposed to a certain kind
of activity, as they are after having been engaged for some time in this
particular work, they are liable to be excited by some stimulus brought
directly to bear on them during sleep. And if this is so, it is not
improbable that many of the apparently forgotten images of persons and
places which return with such vividness in dreams are excited by a mode
of stimulation which is for the greater part confined to sleep. I say
"for the greater part," because even in our indolent, listless moments
of waking existence such seemingly forgotten ideas sometimes return as
though by a spontaneous movement of their own and by no discoverable
play of association.

It may be well to add that this immediate revival of impressions
previously received by the brain includes not only the actual
perceptions of waking life, but also the ideas derived from others, the
ideal fancies supplied by works of fiction, and even the images which
our unaided waking fancy is wont to shape for itself. Our daily
conjectures as to the future, the communications to us by others of
their thoughts, hopes, and fears,--these give rise to numberless vague
fugitive images, any one of which may become distinctly revived in
sleep.[92] This throws light on the curious fact that we often dream of
experiences and events quite unlike those of our individual life. Thus,
for example, the common construction by the dream-fancy of the
experience of flight in mid-air, and the creation of those weird forms
which the terror of a nightmare is wont to bring in its train, seem to
point to the past action of waking fancy. To imagine one's self flying
when looking at a bird is probably a common action with all persons, at
least in their earlier years, and images of preternaturally horrible
beings are apt to be supplied to most of us some time during life by
nurses or by books.

_Indirect Central Stimulation._

Besides these direct central stimulations, there are others which, in
contradistinction, may be called indirect, depending on some previous
excitation. These are, no doubt, the conditions of a very large number
of our dream-images. There must, of course, be some primary cerebral
excitation, whether that of a present peripheral stimulation, or that
which has been termed central and spontaneous; but when once this first
link of the imaginative chain is supplied, other links may be added in
large numbers through the operation of the forces of association. One
may, indeed, safely say that the large proportion of the contents of
every dream arise in this way.

The very simplest type of dream excited by a present sensation contains
these elements. To take an example, I once dreamt, as a consequence of
the loud barking of a dog, that a dog approached me when lying down, and
began to lick my face. Here the play of the associative forces was
apparent: a mere sensation of sound called up the appropriate visual
image, this again the representation of a characteristic action, and so
on. So it is with the dreams whose first impulse is some central or
spontaneous excitation. A momentary sight of a face or even the mention
of a name during the preceding day may give the start to dream-activity;
but all subsequent members of the series of images owe their revival to
a tension, so to speak, in the fine threads which bind together, in so
complicated a way, our impressions and ideas.

Among the psychic accompaniments of these central excitations visual
images, as already hinted, fill the most conspicuous place. Even
auditory images, though by no means absent, are much less numerous than
visual. Indeed, when there are the conditions for the former, it
sometimes happens that the auditory effect transforms itself into a
visual effect. An illustration of this occurred in my own experience.
Trying to fall asleep by means of the well-known device of counting, I
suddenly found myself losing my hold on the faint auditory effects, my
imagination transforming them into a visual spectacle, under the form of
a path of light stretching away from me, in which the numbers appeared
under the grotesque form of visible objects, tumbling along in glorious

Next to these visual phantasms, certain motor hallucinations seem to be
most prominent in dreams. By a motor hallucination, I mean the illusion
that we are actually moving when there is no peripheral excitation of
the motor organ. Just as the centres concerned in passive sensation are
susceptible of central stimulation, so are the centres concerned in
muscular sensation. A mere impulse in the centres of motor innervation
(if we assume these to be the central seat of the muscular feelings) may
suffice to give rise to a complete representation of a fully executed
movement. And thus in our sleep we seem to walk, ride, float, or fly.

The most common form of motor hallucination is probably the vocal. In
the social encounters which make up so much of our sleep-experience, we
are wont to be very talkative. Now, perhaps, we find ourselves zealously
advocating some cause, now very fierce in denunciation, now very amusing
in witty repartee, and so on. This imagination of ourselves as speaking,
as distinguished from that of hearing others talking, must, it is clear,
involve the excitation of the structures engaged in the production of
the muscular feelings which accompany vocal action, as much as, if not
more than, the auditory centres. And the frequency of this kind of
dream-experience may be explained, like that of visual imagery, by the
habits of waking life. The speech impulse is one of the most deeply
rooted of all our impulses, and one which has been most frequently
exercised in waking life.

_Combination of Dream-Elements._

It is commonly said that dreams are a grotesque dissolution of all
order, a very chaos and whirl of images without any discoverable
connection. On the other hand, a few writers claim for the mind in sleep
a power of arranging and grouping its incongruous elements in definite
and even life-like pictures. Each of these views is correct within
certain limits; that is to say, there are dreams in which the strangest
disorder seems to prevail, and others in which one detects the action of
a central control. Yet, speaking generally, sequences of dream-images
will be found to be determined by certain circumstances and laws, and so
far not to be haphazard or wholly chaotic. We have now to inquire into
the laws of these successions; and, first of all, we may ask how far the
known laws of association, together with the peculiar conditions of the
sleeping state, are able to account for the various modes of
dream-combination. We have already regarded mental association as
furnishing a large additional store of dream-imagery; we have now to
consider it as explaining the sequences and concatenations of our

_Incoherence of Dreams._

First of all, then, let us look at the chaotic and apparently lawless
side of dreaming, and see whether any clue is discoverable to the centre
of this labyrinth. In the case of all the less elaborately ordered
dreams, in which sights and sounds appear to succeed one another in the
wildest dance (which class of dreams probably belongs to the deeper
stages of sleep), the mind may with certainty be regarded as purely
passive, and the mode of sequence may be referred to the action of
association complicated by the ever-recurring introduction of new
initial impulses, both peripheral and central. These are the dreams in
which we are conscious of being perfectly passive, either as spectators
of a strange pageant, or as borne away by some apparently extraneous
force through a series of the most diverse experiences. The flux of
images in these dreams is very much the same as that in certain waking
conditions, in which we relax attention, both external and internal, and
yield ourselves wholly to the spontaneous play of memory and fancy.

It is plain at a glance that the simultaneous concurrence of wholly
disconnected initial impulses will serve to impress a measure of
disconnectedness on our dream-images. From widely remote parts of the
organism there come impressions which excite each its peculiar visual or
other image according as its local origin or its emotional tone is the
more distinctly present to consciousness. Now it is a subjective ocular
sensation suggesting a bouquet of lovely flowers, and close on its heels
comes an impression from the organs of digestion suggesting all manner
of obstacles, and so our dream-fancy plunges from a vision of flowers to
one of dreadful demons.

Let us now look at the way in which the laws of association working on
the incongruous elements thus cast up into our dream-consciousness, will
serve to give a yet greater appearance of disorder and confusion to our
dream-combinations. According to these laws, any idea may, under
certain circumstances, call up another, if the corresponding impressions
have only once occurred together, or if the ideas have any degree of
resemblance, or, finally, if only they stand in marked contrast with one
another. Any accidental coincidence of events, such as meeting a person
at a particular foreign resort, and any insignificant resemblance
between objects, sounds, etc., may thus supply a path, so to speak, from
fact to dream-fancy.

In our waking states these innumerable paths of association are
practically closed by the supreme energy of the coherent groups of
impressions furnished us from the world without through our organs of
sense, and also by the volitional control of internal thought in
obedience to the pressure of practical needs and desires. In dream-life
both of these influences are withdrawn, so that delicate threads of
association, which have no chance of exerting their pull, so to speak,
in our waking states, now make known their hidden force. Little wonder,
then, that the filaments which bind together these dream-successions
should escape detection, since even in our waking thought we so often
fail to see the connection which makes us pass in recollection from a
name to a visible scene or perhaps to an emotional vibration.

It is worth noting that the origin of an association is often to be
looked for in one of those momentary half-conscious acts of waking
imagination to which reference has already been made. A friend, for
example, has been speaking to us of some common acquaintance, remarking
on his poor health. The language calls up, vaguely, a visual
representation of the person sinking in health and dying. An
association will thus be formed between this person and the idea of
death. A night or two after, the image of this person somehow recurs to
our dream-fancy, and we straightway dream that we are looking at his
corpse, watching his funeral, and so on. The links of the chain which
holds together these dream-images were really forged, in part, in our
waking hours, though the process was so rapid as to escape our
attention. It may be added, that in many cases where a juxtaposition of
dream-images seems to have no basis in waking life, careful reflection
will occasionally bring to light some actual conjunction of impressions
so momentary as to have faded from our recollection.

We must remember, further, how great an apparent disorder will invade
our imaginative dream-life when the binding force of resemblance has
unchecked play. In waking thought we have to connect things according to
their essential resemblances, classifying objects and events for
purposes of knowledge or action, according to their widest or their most
important points of similarity. In sleep, on the contrary, the slightest
touch of resemblance may engage the mind and affect the direction of
fancy. In a sense we may be said, when dreaming, to discover mental
affinities between impressions and feelings, including those subtle
links of emotional analogy of which I have already spoken. This effect
is well illustrated in a dream recorded by M. Maury, in which he passed
from one set of images to another through some similarity of names, as
that between _corps_ and _cor_. Such a movement of fancy would, of
course, be prevented in full waking consciousness by a predominant
attention to the meaning of the sounds.

It will be possible, I think, after a habit of analyzing one's dreams in
the light of preceding experience has been formed, to discover in a good
proportion of cases some hidden force of association which draws
together the seemingly fortuitous concourse of our dream-atoms. That we
should expect to do so in every case is unreasonable, since, owing to
the numberless fine ramifications which belong to our familiar images,
many of the paths of association followed by our dream-fancy cannot be
afterwards retraced.

To illustrate the odd way in which our images get tumbled together
through the action of occult association forces, I will record a dream
of my own. I fancied I was at the house of a distinguished literary
acquaintance, at her usual reception hour. I expected the friends I was
in the habit of meeting there. Instead of this, I saw a number of
commonly dressed people having tea. My hostess came up and apologized
for having asked me into this room. It was, she said, a tea-party which
she prepared for poor people at sixpence a head. After puzzling over
this dream, I came to the conclusion that the missing link was a verbal
one. A lady who is a connection of my friend, and bears the same name,
assists her sister in a large kind of benevolent scheme. I may add that
I had not, so far as I could recollect, had occasion very recently to
think of this benevolent friend, but I had been thinking of my literary
friend in connection with her anticipated return to town.

In thus seeking to trace, amid the superficial chaos of dream-fancy,
its hidden connections, I make no pretence to explain why in any given
case these particular paths of association should be followed, and more
particularly why a slender thread of association should exert a pull
where a stronger cord fails to do so. To account for this, it would be
necessary to call in the physiological hypothesis that among the nervous
elements connected with a particular element, _a_, already excited,
some, as _m_ and _n_, are at the moment, owing to the state of their
nutrition or their surrounding influences, more powerfully predisposed
to activity than other elements, as _b_ and _c_.

The subject of association naturally conducts us to the second great
problem in the theory of dreams--the explanation of the order in which
the various images group themselves in all our more elaborate dreams.

_Coherence of Dreams._

A fully developed dream is a complex of many distinct illusory
sense-presentations: in this respect it differs from the illusions of
normal waking life, which are for the most part single and isolated. And
this complex of quasi-presentations appears somehow or other to fall
together into one whole scene or series of events, which, though it may
be very incongruous and absurdly impossible from a waking point of view,
nevertheless makes a single object for the dreamer's internal vision,
and has a certain degree of artistic unity. This plastic force, which
selects and binds together our unconnected dream-images, has frequently
been referred to as a mysterious spiritual faculty, under the name of
"creative fancy." Thus Cudworth remarks, in his _Treatise concerning
Eternal and Immutable Morality_: "That dreams are many times begotten by
the phantastical power of the soul itself ... is evident from the
orderly connection and coherence of imaginations which many times are
continued in a long chain or series." One may find a good deal of
mystical writing on the nature and activity of this faculty, especially
in German literature. The explanation of this element of organic unity
in dreams is, it may be safely said, the crux in the science of dreams.
That the laws of psychology help us to understand the sequences of
dream-images, we have seen. What we have now to ask is whether these
laws throw any light on the orderly grouping of the elements so brought
up in consciousness in the form of a connected experience.

It is to be remarked at the outset that a singular kind of unity is
sometimes given to our dream-combinations by a total or partial
coalescence of different images. The conditions of such coalescence have
been referred to already.[93] Simultaneous impressions or images will
always tend to coalesce with a force which varies directly as the degree
of their similarity. Sometimes this coalescence is instantaneous and not
made known to consciousness. Thus, Radestock suggests that if the mind
of the sleeper is simultaneously invaded by an unpleasant sensation
arising out of some disturbance of the functions of the skin, and a
subjective visual sensation, the resulting mental image may be a
combination of the two, under the form of a caterpillar creeping over
the bodily surface. And the coalescence may even be prepared by
sub-conscious operations of waking imagination. Thus, for example, I
once spoke about the cheapness of hares to a member of my family, who
somewhat grimly suggested that they were London cats. I did not dwell on
the idea, but the following night I dreamt that I saw a big hybrid
creature, half hare, half cat, sniffing about a cottage. As it stood on
its hind legs and took a piece of food from a window-ledge, I became
sure that it was a cat. Here it is plain that the cynical observation of
my relative had, at the moment, partially excited an image of this
feline hare. In some dreams, again, we may become aware of the process
of coalescence, as when persons who at one moment were seen to be
distinct appear to our dream-fancy to run together in some third person.

A very similar kind of unification takes place between sequent images
under the form of transformation. When two images follow one another
closely, and have anything in common, they readily assume the form of a
transmutation. There is a sort of overlapping of the mental images, and
so an appearance of continuity produced in some respects analogous to
that which arises in the wheel-of-life (thaumatrope) class of
sense-illusions. This would seem to account for the odd transformations
of personality which not unfrequently occur in dreams, in which a person
appears, by a kind of metempsychosis, to transfer his physical ego to
another, and in which the dreamer's own bodily phantom plays similar
freaks. And the same principle probably explains those dissolving-view
effects which are so familiar an accompaniment of dream-scenery.[94]

But passing from this exceptional kind of unity in dreams, let us
inquire how the heterogeneous elements of our dream-fancy become ordered
and arranged when they preserve their separate existence. If we look
closely at the structure of our more finished dreams, we find that the
appearance of harmony, connectedness, or order, may be given in one of
two ways. There may, first of all, be a subjective harmony, the various
images being held together by an emotional thread. Or there may,
secondly, be an objective harmony, the parts of the dream, though
answering to no particular experiences of waking life, bearing a certain
resemblance to our habitual modes of experience. Let us inquire into the
way in which each kind of order is brought about.

_Lyrical Element in Dreams._

The only unity that belongs to many of our dreams is a subjective
emotional unity. This is the basis of harmony in lyrical poetry, where
the succession of images turns mainly on their emotional colouring.
Thus, the images that float before the mind of the Poet Laureate, in his
_In Memoriam_, clearly have their link of connection in their common
emotional tone, rather than in any logical continuity. Dreaming has been
likened to poetic composition, and certainly many of our dreams are
built upon a groundwork of lyrical feeling. They might be marked off,
perhaps, as our lyrical dreams.

The way in which this emotional force acts in these cases has already
been hinted at. We have seen that the analogy of feeling is a common
link between dream-images. Now, if any shade of feeling becomes fixed
and dominant in the mind, it will tend to control all the images of the
time, allowing certain congruous ones to enter, and excluding
others.[95] If, for example, a feeling of distress occupies the mind,
distressing images will have the advantage in the struggle for existence
which goes on in the world of mind as well as in that of matter. We may
say that attention, which is here wholly a passive process, is
controlled by the emotion of the time, and bent in the direction of
congruent or harmonious images.

Now, a ground-tone of feeling of a certain complexion, answering to the
sum of sensations arising in connection with the different organic
processes of the time, is a very frequent foundation of our
dream-structure. So frequent is it, indeed, that one might almost say
there is no dream in which it is not one great determining factor. The
analysis of a very large number of dreams has convinced me that traces
of this influence are discoverable in a great majority.

I will give a simple illustration of this lyrical type of dream. A
little girl of about four years and three-quarters went with her parents
to Switzerland. On their way she was taken to the cathedral at
Strasburg, and saw the celebrated clock strike, and the figures of the
Apostles come out, etc. In Switzerland she stayed at Gimmelwald, near
Mürren, opposite a fine mass of snowy mountains. One morning she told
her father that she had had "such a lovely dream." She fancied she was
on the snow-peaks with her nurse, and walked on to the sky. There came
out of the sky "such beautiful things," just like the figures of the
clock. This vision of celestial things was clearly due to the fact that
both the clock and the snow-peaks touching the blue sky had powerfully
excited her imagination, filling her with much the same kind of emotion,
namely, wonder, admiration, and longing to reach an inaccessible height.

Our feelings commonly have a gradual rise and fall, and the organic
sensations which so often constitute the emotional basis of our lyrical
dreams generally have stages of increasing intensity. Moreover, such a
persistent ground-feeling becomes reinforced by the images which it
sustains in consciousness. Hence a certain _crescendo_ character in our
emotional dreams, or a gradual rise to some culminating point or climax.

This phase of dream can be illustrated from the experience of the same
little girl. When just five years old, she was staying at Hampstead,
near a church which struck the hours somewhat loudly. One morning she
related the following dream to her father (I use her own language). The
biggest bells in the world were ringing; when this was over the earth
and houses began to tumble to pieces; all the seas, rivers, and ponds
flowed together, and covered all the land with black water, as deep as
in the sea where the ships sail; people were drowned; she herself flew
above the water, rising and falling, fearing to fall in; she then saw
her mamma drowned, and at last flew home to tell her papa. The gradual
increase of alarm and distress expressed in this dream, having its
probable cause in the cumulative effect of the disturbing sound of the
church bells, must be patent to all.

The following rather comical dream illustrates quite as clearly the
growth of a feeling of irritation and vexation, probably connected with
the development of some slightly discomposing organic sensation. I
dreamt I was unexpectedly called on to lecture to a class of young
women, on Herder. I began hesitatingly, with some vague generalities
about the Augustan age of German literature, referring to the three
well-known names of Lessing, Schiller, and Goethe. Immediately my
sister, who suddenly appeared in the class, took me up, and said she
thought there was a fourth distinguished name belonging to this period.
I was annoyed at the interruption, but said, with a feeling of triumph,
"I suppose you mean Wieland?" and then appealed to the class whether
there were not twenty persons who knew the names I had mentioned to one
who knew Wieland's name. Then the class became generally disorderly. My
feeling of embarrassment gained in depth. Finally, as a climax, several
quite young girls, about ten years and less, came and joined the class.
The dream broke off abruptly as I was in the act of taking these
children to the wife of an old college tutor, to protest against their

It is worth noting, perhaps, that in this evolution of feeling in
dreaming the quality of the emotion may vary within certain limits. One
shade of feeling may be followed by another and kindred shade, so that
the whole dream still preserves a degree, though a less obvious degree,
of emotional unity. Thus, for example, a lady friend of mine once dreamt
that she was in church, listening to a well-known novelist of the more
earnest sort, preaching. A wounded soldier was brought in to be shot,
because he was mortally wounded, and had distinguished himself by his
bravery. He was then shot, but not killed, and, rolling over in agony,
exclaimed, "How long!" The development of an extreme emotion of horror
out of the vague feeling of awe which is associated with a church, gives
a curious interest to this dream.

_Verisimilitude in Dreams._

I must not dwell longer on this emotional basis of dreams, but pass to
the consideration of the second and objective kind of unity which
characterizes many of our more elaborate dream-performances. In spite of
all that is fitful and grotesque in dream-combination, it still
preserves a distant resemblance to our actual experience. Though no
dream reproduces a particular incident or chain of incidents in this
experience, though the dream-fancy invariably transforms the particular
objects, relations, and events of waking life, it still makes the order
of our daily experience its prototype. It fashions its imaginary world
on the model of the real. Thus, objects group themselves in space, and
act on one another conformably to these perceived space-relations;
events succeed one another in time, and are often seen to be connected;
men act from more or less intelligible motives, and so on. In this way,
though the dream-fancy sets at nought the particular relations of our
experience, it respects the general and constant relations. How are we
to account for this?

It is said by certain philosophers that this superposition of the
relations of space, time, causation, etc., on the products of our
dream-fancy is due to the fact that all experience arises by a synthesis
of mental forms with the chaotic matter of sense-impressions. These
philosophers allow, however, that all particular connections are
determined by experience. Accordingly, what we have to do here is to
inquire how far this scientific method of explaining mental connections
by facts of experience will carry us. In other words, we have to ask
what light can be thrown on these tendencies of dream-imagination by
ascertained psychological laws, and more particularly by what are known
as the laws of association.

These laws tell us that of two mental phenomena which occur together,
each will tend to recall the other whenever it happens to be revived. On
the physiological side, this means that any two parts of the nervous
structures which have acted together become in some way connected, so
that when one part begins to work the other will tend to work also. But
it is highly probable that a particular structure acts in a great many
different ways. Thus, it may be stimulated by unlike modes of stimuli,
or it may enter into very various connections with other structures.
What will follow from this? One consequence would appear to be that
there will be developed an organic connection between the two
structures, of such a kind that whenever one is excited the other will
be disposed to act somehow and anyhow, even when there is nothing in the
present mode of activity of the first structure to determine the second
to act in some one definite way, in other words, when this mode of
activity is, roughly speaking, novel.

Let me illustrate this effect in one of the simplest cases, that of the
visual organ. If, when walking out on a dark night, a few points in my
retina are suddenly stimulated by rays of light, and I recognize some
luminous object in a corresponding direction, I am prepared to see
something above and below, to the right and to the left of this object.
Why is this? There may from the first have been a kind of innate
understanding among contiguous optic fibres, predisposing them to such
concerted action. But however this be, this disposition would seem to
have been largely promoted by the fact that, throughout my experience,
the stimulation of any retinal point has been connected with that of
adjoining points, either simultaneously by some second object, or
successively by the same object as the eye moves over it, or as the
object itself moves across the field of vision.

When, therefore, in sleep any part of the optic centres is excited in a
particular way, and the images thus arising have their corresponding
loci in space assigned to them, there will be a disposition to refer any
other visual images which happen at the moment to arise in consciousness
to adjacent parts of space. The character of these other images will be
determined by other special conditions of the moment; their locality or
position in space will be determined by this organic connection. We may,
perhaps, call these tendencies to concerted action of some kind general
associative dispositions.

Just as there are such dispositions to united action among various parts
of one organ of sense, so there may be among different organs, which are
either connected originally in the infant organism, or have
communications opened up by frequent coexcitation of the two. Such links
there certainly are between the organs of taste and smell, and between
the ear and the muscular system in general, and more particularly the
vocal organ.[96] A new odour often sets us asking how the object would
taste, and a series of sounds commonly disposes us to movement of some
kind or another. How far there may be finer threads of connection
between other organs, such as the eye and the ear, which do not betray
themselves amid the stronger forces of waking mental life, one cannot
say. Whatever their number, it is plain that they will exert their
influence within the comparatively narrow limits of dream-life, serving
to impress a certain character on the images which happen to be called
up by special circumstances, and giving to the combination a slight
measure of congruity. Thus, if I were dreaming that I heard some lively
music, and at the same time an image of a friend was anyhow excited, my
dream-fancy might not improbably represent this person as performing a
sequence of rhythmic movements, such as those of riding, dancing, etc.

A narrower field for these general associative dispositions may be found
in the tendency, on the reception of an impression of a given character,
to look for a certain kind of second impression; though the exact nature
of this is unknown. Thus, for example, the form and colour of a new
flower suggest a scent, and the perception of a human form is
accompanied by a vague representation of vocal utterances. These general
tendencies of association appear to me to be most potent influences in
our dream-life. The many strange human forms which float before our
dream-fancy are apt to talk, move, and behave like men and women in
general, however little they resemble their actual prototypes, and
however little individual consistency of character is preserved by each
of them. Special conditions determine what they shall say or do; the
general associative disposition accounts for their saying or doing

We thus seem to find in the purely passive processes of association some
ground for that degree of natural coherence and rational order which our
more mature dreams commonly possess. These processes go far to explain,
too, that odd mixture of rationality with improbability, of natural
order and incongruity, which characterizes our dream-combinations.

_Rational Construction in Dreams._

Nevertheless, I quite agree with Herr Volkelt that association, even in
the most extended meaning, cannot explain all in the shaping of our
dream-pictures. The "phantastical power" which Cudworth talks about
clearly includes something besides. It is an erroneous supposition that
when we are dreaming there is a complete suspension of the voluntary
powers, and consequently an absence of all direction of the intellectual
processes. This supposition, which has been maintained by numerous
writers, from Dugald Stewart downwards, seems to be based on the fact
that we frequently find ourselves in dreams striving in vain to move the
whole body or a limb. But this only shows, as M. Maury remarks in the
work already referred to, that our volitions are frustrated through the
inertia of our bodily organs, not that these volitions do not take
place. In point of fact, the dreamer, not to speak of the somnambulist,
is often conscious of voluntarily going through a series of actions.
This exercise of volition is shown unmistakably in the well-known
instances of extraordinary intellectual achievements in dreams, as
Condillac's composition of a part of his _Cours d'Études_. No one would
maintain that a result of this kind was possible in the total absence of
intellectual action carefully directed by the will. And something of
this same control shows itself in all our more fully developed dreams.

One manifestation of this voluntary activity in sleep is to be found in
those efforts of attention which not unfrequently occur. I have remarked
that, speaking roughly and in relation to the waking condition, the
state of sleep is marked by a subjection of the powers of attention to
the force of the mental images present to consciousness. Yet something
resembling an exercise of voluntary attention sometimes happens in
sleep. The intellectual feats just spoken of, unless, indeed, they are
referred to some mysterious unconscious mental operations, clearly
involve a measure of volitional guidance. All who dream frequently are
occasionally aware on awaking of having greatly exercised their
attention on the images presented to them during sleep. I myself am
often able to recall an effort to see beautiful objects, which
threatened to disappear from my field of vision, or to catch faint
receding tones of preternatural sweetness; and some dreamers allege that
they are able to retain a recollection of the feeling of strain
connected with such exercise of attention in sleep.

The main function of this voluntary attention in dream-life is seen in
the selection of those images which are to pass the threshold of clear
consciousness. I have already spoken of a selective action brought about
by the ruling emotion. In this case, the attention is held captive by
the particular feeling of the moment. Also a selective process goes on
in the case of the action of those associative dispositions just
referred to. But in each of these cases the action of selective
attention is comparatively involuntary, passive, and even unconscious,
not having anything of the character of a conscious striving to compass
some end. Besides this comparatively passive play of selective
attention, there is an active play, in which there is a conscious wish
to gain an end; in other words, the operation of a definite motive. This
motive may be described as an intellectual impulse to connect and
harmonize what is present to the mind. The voluntary kind of selection
includes and transcends each of the involuntary kinds. It has as its
result an imitation of that order which is brought about by what I have
called the associative dispositions, only it consciously aims at this
result. And it is a process controlled by a feeling, namely, the
intellectual sentiment of consistency, which is not a mode of emotional
excitement enthralling the will, but a calm motive, guiding the
activities of attention. It thus bears somewhat the same relation to the
emotional selection already spoken of, as dramatic creation bears to
lyrical composition.

This process of striving to seize some connecting link, or thread of
order, is illustrated whenever, in waking life, we are suddenly brought
face to face with an unfamiliar scene. When taken into a factory, we
strive to arrange the bewildering chaos of visual impressions under some
scheme, by help of which we are said to understand the scene. So, if on
entering a room we are plunged in _medias res_ of a lively conversation,
we strive to find a clue to the discussion. Whenever the meaning of a
scene is not at once clear, and especially whenever there is an
appearance of confusion in it, we are conscious of a painful feeling of
perplexity, which acts as a strong motive to ever-renewed attention.[97]

In touching on this intellectual impulse to connect the disconnected, we
are, it is plain, approaching the question of the very foundations of
our intellectual structure. That there is this impulse firmly rooted in
the mature mind nobody can doubt; and that it manifests itself in early
life in the child's recurring "Why?" is equally clear. But how we are to
account for it, whether it is to be viewed as a mere result of the play
of associated fragments of experience, or as something involved in the
very process of the association of ideas itself, is a question into
which I cannot here enter.

What I am here concerned to show is that the search for consistency and
connection in the manifold impressions of the moment is a deeply rooted
habit of the mind, and one which is retained in a measure during sleep.
When, in this state, our minds are invaded by a motley crowd of
unrelated images, there results a disagreeable sense of confusion; and
this feeling acts as a motive to the attention to sift out those
products of the dream-fancy which may be made to cohere. When once the
foundations of a dream-action are laid, new images must to some extent
fit in with this; and here there is room for the exercise of a distinct
impulse to order the chaotic elements of dream-fancy in certain forms.
The perception of any possible relation between one of the crowd of new
images ever surging above the level of obscure consciousness, and the
old group at once serves to detain it. The concentration of attention on
it, in obedience to this impulse to seek for an intelligible order, at
once intensifies it and fixes it, incorporating it into the series of

Here is a dream which appears to illustrate this impulse to seek an
intelligible order in the confused and disorderly. After being occupied
with correcting the proofs of my volume on _Pessimism_, I dreamt that my
book was handed to me by my publisher, fully illustrated with coloured
pictures. The frontispiece represented the fantastic figure of a man
gesticulating in front of a ship, from which he appeared to have just
stepped. My publisher told me it was meant for Hamlet, and I immediately
reflected that this character had been selected as a concrete example of
the pessimistic tendency. I may add that, on awaking, I was distinctly
aware of having felt puzzled when dreaming, and of having striven to
read a meaning into the dream.

The _rationale_ of this dream seems to me to be somewhat as follows. The
image of the completed volume represented, of course, a recurring
anticipatory image of waking life. The coloured plates were due probably
to subjective optical sensations simultaneously excited, which were made
to fit in (with or without an effort of voluntary attention) with the
image of the book under the form of illustrations. But this stage of
coherency did not satisfy the mind, which, still partly confused by the
incongruity of coloured plates in a philosophic work, looked for a
closer connection. The image of Hamlet was naturally suggested in
connection with pessimism. The effort to discover a meaning in the
pictures led to the fusion of this image with one of the subjective
spectra, and in this way the idea of a Hamlet frontispiece probably

The whole process of dream-construction is clearly illustrated in a
curious dream recorded by Professor Wundt.[98] Before the house is a
funeral procession: it is the burial of a friend, who has in reality
been dead for some time past. The wife of the deceased bids him and an
acquaintance who happens to be with him go to the other side of the
street and join the procession. After she has gone away, his companion
remarks to him, "She only said that because the cholera rages over
yonder, and she wants to keep this side of the street to herself." Then
comes an attempt to flee from the region of the cholera. Returning to
his house, he finds the procession gone, but the street strewn with
rich nosegays; and he further observes crowds of men who seem to be
funeral attendants, and who, like himself, are hastening to join the
procession. These are, oddly enough, dressed in red. When hurrying on,
it occurs to him that he has forgotten to take a wreath for the coffin.
Then he wakes up with beating of the heart.

The sources of this dream are, according to Wundt, as follows. First of
all, he had, on the previous day, met the funeral procession of an
acquaintance. Again, he had read of cholera breaking out in a certain
town. Once more, he had talked about the particular lady with this
friend, who had narrated facts which clearly proved her selfishness. The
hastening to flee from the infected neighbourhood and to overtake the
procession was prompted by the sensation of heart-beating. Finally, the
crowd of red bier-followers, and the profusion of nosegays, owed their
origin to subjective visual sensations, the "light-chaos" which often
appears in the dark.

Let us now see for a moment how these various elements may have become
fused into a connected chain of events. First of all, it is clear that
this dream is built up on a foundation of a gloomy tone of feeling,
arising, as it would seem, from an irregularity of the heart's action.
Secondly, it owes its special structure and its air of a connected
sequence of events, to those tendencies, passive and active, to order
the chaotic of which I have been speaking. Let us try to trace this out
in detail.

To begin with, we may suppose that the image of the procession occupies
the dreamer's mind. From quite another source the image of the lady
enters consciousness, bringing with it that of her deceased husband and
of the friend who has recently been talking about her. These new
elements adapt themselves to the scene, partly by the passive mechanism
of associative dispositions, and partly, perhaps, by the activity of
voluntary selection. Thus, the idea of the lady's husband would
naturally recall the fact of his death, and this would fall in with the
pre-existing scene under the form of the idea that he is the person who
is now being buried. The next step is very interesting. The image of the
lady is associated with the idea of selfish motives. This would tend to
suggest a variety of actions, but the one which becomes a factor of the
dream is that which is specially adapted to the pre-existing
representations, namely, of the procession on the further side of the
street, and the cholera (which last, like the image of the funeral, is,
we may suppose, due to an independent central excitation). That is to
say, the request of the lady, and its interpretation, are a _resultant_
of a number of adaptative or assimilative actions, under the sway of a
strong desire to connect the disconnected, and a lively activity of
attention. Once more, the feeling of oppression of the heart, and the
subjective stimulation of the optic nerve, might suggest numberless
images besides those of anxious flight and of red-clad men and nosegays;
they suggest these, and not others, in this particular case, because of
the co-operation of the impulse of consistency, which, setting out with
the pre-existing mental images, selects from among many tendencies of
reproduction those which happen to chime in with the scene.

_The Nature of Dream-Intelligence._

It must not be supposed that this process of welding together the
chaotic materials of our dreams is ever carried out with anything like
the clear rational purpose of which we are conscious when seeking, in
waking life, to comprehend some bewildering spectacle. At best it is a
vague longing, and this longing, it may be added, is soon satisfied.
There is, indeed, something, almost pathetic in the facility with which
the dreamer's mind can be pacified with the least appearance of a
connection. Just as a child's importunate "Why?" is often silenced by a
ridiculous caricature of an explanation, so the dreamer's intelligence
is freed from its distress by the least semblance of a uniting order.

It thus remains true with respect even to our most coherent dreams, that
there is a complete suspension, or at least a considerable retardation,
of the highest operations of judgment and thought; also a great
enfeeblement, to say the least of it, of those sentiments such as the
feeling of consistency and the sense of the absurd which are so
intimately connected with these higher intellectual operations.

In order to illustrate how oddly our seemingly rational dreams
caricature the operations of waking thought, I may, perhaps, be allowed
to record two of my own dreams, of which I took careful note at the

On the first occasion I went "in my dream" to the "Stores" in August,
and found the place empty. A shopman brought me some large fowls. I
asked their price, and he answered, "Tenpence a pound." I then asked
their weight, so as to get an idea of their total cost, and he replied,
"Forty pounds." Not in the least surprised, I proceeded to calculate
their cost: 40x10=400÷12=33-1/3. But, oddly enough, I took this quotient
as pence, just as though I had not already divided by 12, and so made
the cost of a fowl to be 2s. 9d., which seemed to me a fair enough

In my second dream I was at Cambridge, among a lot of undergraduates. I
saw a coach drive up with six horses. Three undergraduates got out of
the coach. I asked them why they had so many horses, and they said,
"Because of the luggage." I then said, "The luggage is much more than
the undergraduates. Can you tell me how to express this in mathematical
symbols? This is the way: if _x_ is the weight of an undergraduate, then
_x_ + _x_.n represents the weight of an undergraduate and his luggage
together." I noticed that this sally was received with evident

We may say, then, that the structure of our dreams, equally with the
fact of their completely illusory character, points to the conclusion
that during sleep, just as in the moments of illusion in waking life,
there is a deterioration of our intellectual life. The highest
intellectual activities answering to the least stable nervous
connections are impeded, and what of intellect remains corresponds to
the most deeply organized connections.

In this way, our dream-life touches that childish condition of the
intelligence which marks the decadence of old age and the encroachments
of mental disease. The parallelism between dreams and insanity has been
pointed out by most writers on the subject. Kant observed that the
madman is a dreamer awake, and more recently Wundt has remarked that,
when asleep, we "can experience nearly all the phenomena which meet us
in lunatic asylums." The grotesqueness of the combinations, the lack of
all judgment as to consistency, fitness, and probability, are common
characteristics of the short night-dream of the healthy and the long
day-dream of the insane.[100]

But one great difference marks off the two domains. When dreaming, we
are still sane, and shall soon prove our sanity. After all, the dream of
the sleeper is corrected, if not so rapidly as the illusion of the
healthy waker. As soon as the familiar stimuli of light and sound set
the peripheral sense-organs in activity, and call back the nervous
system to its complete round of healthy action, the illusion disappears,
and we smile at our alarms and agonies, saying, "Behold, it was a

On the practical side, the illusions and hallucinations of sleep must be
regarded as comparatively harmless. The sleeper, in healthy conditions
of sleep, ceases to be an agent, and the illusions which enthral his
brain have no evil practical consequences. They may, no doubt, as we
shall see in a future chapter, occasionally lead to a subsequent
confusion of fiction and reality in waking recollection. But with the
exception of this, their worst effect is probably the lingering sense of
discomfort which a "nasty dream" sometimes leaves with us, though this
may be balanced by the reverberations of happy dream-emotions which
sometimes follow us through the day. And however this be, it is plain
that any disadvantages thus arising are more than made good by the
consideration that our liability to these nocturnal illusions is
connected with the need of that periodic recuperation of the higher
nervous structures which is a prime condition of a vigorous intellectual
activity, and so of a triumph over illusion during waking life.

For these reasons dreams may properly be classed with the illusions of
normal or healthy life, rather than with those of disease. They
certainly lie nearer this region than the very similar illusions of the
somnambulist, which with respect to their origin appear to be more
distinctly connected with a pathological condition of the nervous
system, and which, with respect to their practical consequences may
easily prove so disastrous.


In concluding this account of dreams, I would call attention to the
importance of the transition states between sleeping and waking, in
relation to the production of sense-illusion. And this point may be
touched on here all the more appropriately, since it helps to bring out
the close relation between waking and sleeping illusion. The mind does
not pass suddenly and at a bound from the condition of dream-fancy to
that of waking perception. I have already had occasion to touch on the
"hypnagogic state," that condition of somnolence or "sleepiness" in
which external impressions cease to act, the internal attention is
relaxed, and the weird imagery of sleep begins to unfold itself. And
just as there is this anticipation of dream-hallucination in the
presomnial condition, so there is the survival of it in the postsomnial
condition. As I have observed, dreams sometimes leave behind them, for
an appreciable interval after waking, a vivid after-impression, and in
some cases even the semblance of a sense-perception.

If one reflects how many ghosts and other miraculous apparitions are
seen at night, and when the mind is in a more or less somnolent
condition, the idea is forcibly suggested that a good proportion of
these visions are the _débris_ of dreams. In some cases, indeed, as that
of Spinoza, already referred to, the hallucination (in Spinoza's case
that of "a scurvy black Brazilian") is recognized by the subject himself
as a dream-image.[101] I am indebted to Mr. W.H. Pollock for a fact
which curiously illustrates the position here adopted. A lady was
staying at a country house. During the night and immediately on waking
up she had an apparition of a strange-looking man in mediæval costume,
a figure by no means agreeable, and which seemed altogether unfamiliar
to her. The next morning, on rising, she recognized the original of her
hallucinatory image in a portrait hanging on the wall of her bedroom,
which must have impressed itself on her brain before the occurrence of
the apparition, though she had not attended to it. Oddly enough, she now
learnt for the first time that the house at which she was staying had
the reputation of being haunted, and by the very same somewhat
repulsive-looking mediæval personage that had troubled her
inter-somnolent moments. The case seems to me to be typical with respect
to the genesis of ghosts, and of the reputation of haunted houses.

       *       *       *       *       *



I have not in this chapter discussed the relation of dreaming to
hypnotism, or the state of artificially produced quasi-sleep, because
the nature of this last is still but very imperfectly understood. In
this condition, which is induced in a number of ways by keeping the
attention fixed on some non-exciting object, and by weak continuous and
monotonous stimulation, as stroking the skin, the patient can be made to
act conformably to the verbal or other suggestion of the operator, or to
the bodily position which he is made to assume. Thus, for example, if a
glass containing ink is given to him, with the command to drink, he
proceeds to drink. If his hands are folded, he proceeds to act as if he
were in church, and so on.

Braid, the writer who did so much to get at the facts of hypnotism, and
Dr. Carpenter who has helped to make known Braid's careful researches,
regard the actions of the hypnotized subject as analogous to ideomotor
movements; that is to say, the movements due to the tendency of an idea
to act itself out apart from volition. On the other hand, one of the
latest inquirers into the subject, Professor Heidenhain, of Breslau,
appears to regard these actions as the outcome of "unconscious
perceptions" (_Animal Magnetism_, English translation, p. 43, etc.).

In the absence of certain knowledge, it seems allowable to argue from
the analogy of natural sleep that the actions of the hypnotized patient
are accompanied with the lower forms of consciousness, including
sensation and perception, and that they involve dream-like
hallucinations respecting the external circumstances of the moment.
Regarding them in this light, the points of resemblance between
hypnotism and dreaming are numerous and striking. Thus, Dr. Heidenhain
tells us that the threshold or liminal value of stimulation is lowered
just as in ordinary sleep sense-activity as a whole is lowered.
According to Professor Weinhold, the hypnotic condition begins in a
gradual loss of taste, touch, and the sense of temperature; then sight
is gradually impaired, while hearing remains throughout the least
interfered with.[102] In this way, the mind of the patient is largely
cut off from the external world, as in sleep, and the power of
orientation is lost. Moreover, there are all the conditions present,
both positive and negative, for the hallucinatory transformation of
mental images into percepts just as in natural sleep. Thus, the higher
centres connected with the operations of reflection and reasoning are
thrown _hors de combat_ or, as Dr. Heidenhain has it, "inhibited."

The condition of hypnotism is marked off from that of natural sleep,
first of all, by the fact that the accompanying hallucinations are
wholly due to external suggestion (including the effects of bodily
posture). Dreams may, as we have seen, be very faintly modified by
external influences, but during sleep there is nothing answering to the
perfect control which the operator exercises over the hypnotized
subject. The largest quantity of our "dream-stuff" comes, as we have
seen, from within and not from without the organism. And this fact
accounts for the chief characteristic difference between the natural and
the hypnotic dream. The former is complex, consisting of crowds of
images, and continually changing: the latter is simple, limited, and
persistent. As Braid remarks, the peculiarity of hypnotism is that the
attention is concentrated on a remarkably narrow field of mental images
and ideas. So long as a particular bodily posture is assumed, so long
does the corresponding illusion endure. One result of this, in
connection with that impairing of sensibility already referred to, is
the scope for a curious overriding of sense-impressions by the dominant
illusory percept, a process that we have seen illustrated in the active
sense-illusions of waking life. Thus, if salt water is tasted and the
patient is _told_ that it is beer, he complains that it is sour.

In being thus in a certain rapport, though so limited and unintelligent
a rapport, with the external world, the mind of the hypnotized patient
would appear to be nearer the condition of waking illusion than is the
mind of the dreamer. It must be remembered, however, and this is the
second point of difference between dreaming and hypnotism, that the
hypnotized subject tends _to act out_ his hallucinations. His
quasi-percepts are wont to transform themselves into actions with a
degree of force of which we see no traces in ordinary sleep. Why there
should be this greater activity of the motor organs in the one condition
than in the other, seems to be a point as yet unexplained. All
sense-impressions and percepts are doubtless accompanied by some degree
of impulse to movement, though, for some reason or another, in natural
and healthy sleep these impulses are restricted to the stage of faint
nascent stirrings of motor activity which hardly betray themselves
externally. This difference, involving a great difference in the
possible practical consequences of the two conditions of natural and
hypnotic sleep, clearly serves to bring the latter condition nearer to
that of insanity than the former condition is brought. A strong
susceptibility to the hypnotic influence, such as Dr. Heidenhain
describes, might, indeed, easily prove a very serious want of
"adaptation of internal to external relations," whereas a tendency to
dreaming would hardly prove a maladaptation at all.



We have now, perhaps, sufficiently reviewed sense-illusions, both of
waking life and of sleep. And having roughly classified them according
to their structure and origin, we are ready to go forwards and inquire
whether the theory thus reached can be applied to other forms of
illusory error. And here we are compelled to inquire at the outset if
anything analogous to sense-illusion is to be found in that other great
region of presentative cognition usually marked off from external
perception as internal perception, self-reflection, or introspection.

_Illusions of Introspection defined._

This inquiry naturally sets out with the question: What is meant by
introspection? This cannot be better defined, perhaps, than by saying
that it is the mind's immediate reflective cognition of its own states
as such.

In one sense, of course, everything we know may be called a mental
state, actual or imagined. Thus, a sense-impression is known, exactly
like any other feeling of the mind, as a mental phenomenon or mental
modification. Yet we do not usually speak of introspectively
recognizing a sensation. Our sense-impressions are marked off from all
other feelings by having an objective character, that is to say, an
immediate relation to the external world, so that in attending to one of
them our minds pass away from themselves in what Professor Bain calls
the attitude of objective regard. Introspection is confined to feelings
which want this intimate connection with the external region, and
includes sensation only so far as it is viewed apart from external
objects and on its mental side as a feeling, a process which is next to
impossible where the sensation has little emotional colour, as in the
case of an ordinary sensation of sight or of articulate sound.

This being so, errors of introspection, supposing such to be found, will
in the main be sufficiently distinguished from those of perception. Even
an hallucination of sense, whether setting out from a subjective
sensation or not, always contains the semblance of a sense-impression,
and so would not be correctly classed with errors of introspection.

Just as introspection must be marked off from perception, so must it be
distinguished from memory. It may be contended that, strictly speaking,
all introspection is retrospection, since even in attending to a present
feeling the mind is reflectively representing to itself the immediately
preceding momentary experience of that feeling. Yet the adoption of this
view does not hinder us from drawing a broad distinction between acts of
introspection and acts of memory. Introspection must be regarded as
confined to the knowledge of immediately antecedent mental states with
reference to which, no error of memory can be supposed to arise.

It follows from this that an illusion of introspection could only be
found in connection with the apprehension of present or immediately
antecedent mental states. On the other hand, any illusions connected
with the consciousness of personal continuity and identity would fall
rather under the class of mnemonic than that of introspective error.

Once more, introspection must be carefully distinguished from what I
have called belief. Some of our beliefs may be found to grow out of and
be compounded of a number of introspections. Thus, my conception of my
own character, or my psychological conception of mind as a whole, may be
seen to arise by a combination of the results of a number of acts of
introspection. Yet, supposing this to be so, we must still distinguish
between the single presentative act of introspection and the
representative belief growing out of it.

It follows from this that, though an error of the latter sort might
conceivably have its origin in one of the former; though, for example, a
man's illusory opinion of himself might be found to involve errors of
introspection, yet the two kinds of illusion would be sufficiently
unlike. The latter would be a simple presentative error, the former a
compound representative error.

Finally, in order to complete this preliminary demarcation of our
subject-matter, it is necessary to distinguish between an introspection
(apparent or real) of a feeling or idea, and a process of inference
based on this feeling. The term introspective knowledge must, it is
plain, be confined to what is or appears to be in the mind at the moment
of inspection.

By observing this distinction, we are in a position to mark off an
_illusion_ of introspection from a _fallacy_ of introspection. The
former differs from the latter in the absence of anything like a
conscious process of inference. Thus, if we suppose that the derivation
by Descartes of the fact of the existence of God from his possession of
the idea to be erroneous, such a consciously performed act of reasoning
would constitute a fallacy rather than an illusion of introspection.

We may, then, roughly define an illusion of introspection as an error
involved in the apprehension of the contents of the mind at any moment.
If we mistake the quality or degree of a feeling or the structure of a
complex mass of feeling, or if we confuse what is actually present to
the mind with some inference based on this, we may be said to fall into
an illusion of introspection.

But here the question will certainly be raised: How can we conceive the
mind erring as to the nature of its present contents; and what is to
determine, if not my immediate act of introspection, what is present in
my mind at any moment? Indeed, to raise the possibility of error in
introspection seems to do away with the certainty of presentative

If, however, the reader will recall what was said in an earlier chapter
about the possibility of error in recognizing the quality of a
sense-impression, he will be prepared for a similar possibility here.
What we are accustomed to call a purely presentative cognition is, in
truth, partly representative. A feeling as pure feeling is not known; it
is only known when it is distinguished, as to quality or degree, and so
classed or brought under some representation of a kind or description of
feeling, as acute, painful, and so on. The accurate recognition of an
impression of colour depends, as we have seen, on this process of
classing being correctly performed. Similarly, the recognition of
internal feelings implies the presence of the appropriate or
corresponding class-representation. Accordingly, if it is possible for a
wrong representation to get substituted for the right one, there seems
to be an opening for error.

Any error that would thus arise can, of course, only be determined as
such in relation to some other act of introspection of the same mind. In
matters of internal perception other minds cannot directly assist us in
correcting error as they can in the case of external perception, though,
as we shall see by-and-by, they may do so indirectly. The standard of
reality directly applicable to introspective cognition is plainly what
the individual mind recognizes at its best moments, when the processes
of attention and classifying are accurately performed, and the
representation may be regarded with certainty as answering to the
feeling. In other words, in the sphere of internal, as in that of
external experience, the criterion of reality is the average and
perfect, as distinguished from the particular variable and imperfect act
of cognition.

We see, then, that error in the process of introspection is at least
conceivable. And now let us examine this process a little further, in
order to find out what probabilities of error attach to it.

To begin with, then, an act of introspection, to be complete, clearly
involves the apprehension of an internal feeling or idea as something
mental and marked off from the region of external experience. This
distinct recognition of internal states of mind as such, in opposition
to external impressions, is by no means easy, but presupposes a certain
degree of intellectual culture, and a measure of the power of abstract

_Confusion of Internal and External Experience._

Accordingly, we find that where this is wanting there is a manifest
disposition to translate internal feelings into terms of external
impressions. In this way there may arise a slight amount of habitual and
approximately constant error. Not that the process approaches to one of
hallucination; but only that the internal feelings are intuited as
having a cause or origin analogous to that of sense-impressions. Thus to
the uncultivated mind a sudden thought seems like an audible
announcement from without. The superstitious man talks of being led by
some good or evil spirit when new ideas arise in his mind or new
resolutions shape themselves. To the simple intelligence of the boor
every thought presents itself as an analogue of an audible voice, and he
commonly describes his rough musings as saying this and that to himself.
And this, mode of viewing the matter is reflected even, in the language
of cultivated persons. Thus we say, "The idea struck me," or "was borne
in on me," "I was forced to do so and so," and so on, and in this
manner we tend to assimilate internal to external mental phenomena.

Much the same thing shows itself in our customary modes of describing
our internal feelings of pleasure and pain. When a man in a state of
mental depression speaks of having "a load" on his mind it is evident
that he is interpreting a mental by help of an analogy to a bodily
feeling. Similarly, when we talk of the mind being torn by doubt or worn
by anxiety. It would seem as though we tended mechanically to translate
mental pleasures and pains into the language of bodily sensations.

The explanation of this deeply rooted tendency to a slightly illusory
view of our mental states is, I think, an easy one. For one thing, it
follows from the relation of the mental image to the sense-impression
that we should tend to assimilate the former to the latter as to its
nature and origin. This would account for the common habit of regarding
thoughts, which are of course accompanied by representatives of their
verbal symbols, as internal voices, a habit which is probably especially
characteristic of the child and the uncivilized man, as we have found it
to be characteristic of the insane.

Another reason, however, must be sought for the habit of assimilating
internal feelings to external sensations. If language has been evolved
as an incident of social life, at once one of its effects and its
causes, it would seem to follow that it must have first shaped Itself to
the needs of expressing these common objective experiences which we
receive by way of our senses. Our habitual modes of thought, limited as
they are by language, retain traces of this origin. We cannot conceive
any mental process except by some vague analogy to a physical process.
In other words, we can even now only think with perfect clearness when
we are concerned with some object of common cognition. Thus, the sphere
of external sensation and of physical agencies furnishes us with the one
type of thinkable thing or object of thought, and we habitually view
subjective mental states as analogues of these.

Still, it may be said that these slight nascent errors are hardly worth
naming, and the question would still appear to recur whether there are
other fully developed errors deserving to rank along with illusions of
sense. Do we, it may be asked, ever actually mistake the quality,
degree, or structure of our internal feelings in the manner hinted
above, and if so, what is the range of such error? In order to
appreciate the risks of such error, let us compare the process of
self-observation with that of external perception with respect to the
difficulties in the way of accurate presentative knowledge.

_Misreading of Internal Feelings._

First of all, it is noteworthy that a state of consciousness at any one
moment is an exceedingly complex thing. It is made up of a mass of
feelings and active impulses which often combine and blend in a most
inextricable way. External sensations come in groups, too, but as a rule
they do not fuse in apparently simple wholes as our internal feelings
often do. The very possibility of perception depends on a clear
discrimination of sense-elements, for example, the several sensations
of colour obtained by the stimulation of different parts of the
retina.[103] But no such clearly defined mosaic of feelings presents
itself in the internal region: one element overlaps and partly loses
itself in another, and subjective analysis is often an exceedingly
difficult matter. Our consciousness is thus a closely woven texture in
which the mental eye often fails to trace the several threads or
strands. Moreover, there is the fact that many of these ingredients are
exceedingly shadowy, belonging to that obscure region of
sub-consciousness which it is so hard to penetrate with the light of
discriminative attention. This remark applies with particular force to
that mass of organic feelings which constitutes what is known as
coenæsthesis; or vital sense.

While, to speak figuratively, the minute anatomy of consciousness is
thus difficult with respect to longitudinal sections of the mental
column, it is no less difficult with respect to transverse sections.
Under ordinary circumstances, external impressions persist so that they
can be transfixed by a deliberate act of attention, and objects rarely
flit over the external scene so rapidly as to allow us no time for a
careful recognition of the impression. Not so in the case of the
internal region of mind. The composite states of consciousness just
described never remain perfectly uniform for the shortest conceivable
duration. They change continually, just as the contents of the
kaleidoscope vary with every shake of the instrument. Thus, one shade
of feeling runs into another in such a way that it is often impossible
to detect its exact quality; and even when the character of the feeling
does not change, its intensity is undergoing alterations so that an
accurate observation of its quantity is impracticable. Also, in this
unstable shifting internal scene features may appear for a duration too
short to allow of close recognition. In this way it happens that we
cannot sharply divide the feeling of the moment from its antecedents and
its consequents.

If, now, we take these facts in connection with what has been said above
respecting the nature of the process of introspection, the probability
of error will be made sufficiently clear. To transfix any particular
feeling of the moment, to selectively attend to it, and to bring it
under the proper representation, is an operation that requires time, a
time which, though short, is longer than the fugitive character of so
much of our internal mental life allows. From all of which it would
appear to follow that it must be very easy to overlook, confuse, and
transform, both as to quality and as to quantity, the actual ingredients
of our internal consciousness.

From these sources there spring a number of small errors of
introspection which, to distinguish them from others to be spoken of
presently, may be called passive. These would include all errors in
detecting what is in consciousness due to the intricacies of the
phenomena, and not aided by any strong basis. For example, a mental
state may fail to disclose its component parts to introspective
attention. Thus, a motive may enter into our action which is so
entangled with other feelings as to escape our notice. The fainter the
feeling the greater the difficulty of detaching it and inspecting it in
isolation. Again, an error of introspection may have its ground in the
fugitive character of a feeling. If, for example, a man is asked whether
a rapid action was a voluntary one, he may in retrospection easily
imagine that it was not so, when as a matter of fact the action was
preceded by a momentary volition. When a person exclaims, "I did a thing
inadvertently or mechanically," it often means that he did not note the
motive underlying the action. Such transitory feelings which cannot at
the moment be seized by an act of attention are pretty certain to
disappear at once, leaving not even a temporary trace in consciousness.

We will now pass to the consideration of other illusions of
introspection more analogous to what I have called the active illusions
of perception. In our examination of these we found that a pure
representation may under certain circumstances simulate the appearance
of a presentation, that a mental image may approximate to a
sense-impression. In the case of the internal feelings this liability
shows itself in a still more striking form.

The higher feelings or emotions are distinguished from the simple
sense-feelings in being largely representative. Thus, a feeling of
contentment at any moment, though no doubt conditioned by the bodily
state and the character of the organic sensations or coenæsthesis,
commonly depends for the most part on intellectual representations of
external circumstances or relations, and may be called an ideal
foretaste of actual satisfactions, such as the pleasures of success, of
companionship, and so on. This being so, it is easy for imagination to
call up a semblance of these higher feelings. Since they depend largely
on representation, a mere act of representation may suffice to excite a
degree of the feeling hardly distinguishable from the actual one. Thus,
to imagine myself as contented is really to see myself at the moment as
actually contented. Again, the actor, though, as we shall see by-and-by,
he does not feel all that the spectator is apt to attribute to him,
tends, when vividly representing to himself a particular shade of
feeling, to regard himself as actually feeling in this way. Thus, it is
said of Garrick, that when acting Richard III., he felt himself for the
moment to be a villain.

We should expect from all this that in the act of introspection the mind
is apt, within certain limits, to find what it is prepared to find. And
since there is in these acts often a distinct wish to detect some
particular feeling, we can see how easy it must be for a man through
bias and a wrong focussing of the attention to deceive himself up to a
certain point with respect to the actual contents of his mind.

Let us examine one of these active illusions a little more fully. It
would at first sight seem to be a perfectly simple thing to determine at
any given moment whether we are enjoying ourselves, whether our
emotional condition rises above the pleasure-threshold or point of
indifference and takes on a positive hue of the agreeable or
pleasurable. Yet there is good reason for supposing that people not
unfrequently deceive themselves on this matter. It is, perhaps, hardly
an exaggeration to say that most of us are capable of imagining that we
are having enjoyment when we conform to the temporary fashion of social
amusement. It has been cynically observed that people go into society
less in order to be happy than to seem so, and one may add that in this
semblance of enjoyment they may, provided they are not _blasé_, deceive
themselves as well as others. The expectation of enjoyment, the
knowledge that the occasion is intended to bring about this result, the
recognition of the external signs of enjoyment in others--all this may
serve to blind a man in the earlier stages of social amusement to his
actual mental condition.

If we look closely into this variety of illusion, we shall see that it
is very similar in its structure and origin to that kind of erroneous
perception which arises from inattention to the actual impression of the
moment under the influence of a strong expectation of something
different. The representation of ourselves as entertained dislodges from
our internal field of vision our actual condition, relegating this to
the region of obscure consciousness. Could we for a moment get rid of
this representation and look at the real feelings of the time, we should
become aware of our error; and it is possible that the process of
becoming _blasé_ involves a waking up to a good deal of illusion of the

Just as we can thus deceive ourselves within certain limits as to our
emotional condition, so we can mistake the real nature of our
intellectual condition. Thus, when an idea is particularly grateful to
our minds, we may easily imagine that we believe it, when in point of
fact all the time there is a sub-conscious process of criticism going
on, which if we attended to it for a moment would amount to a distinct
act of disbelief. Some persons appear to be capable of going on
habitually practising this petty deceit on themselves, that is to say,
imagining they believe what in fact they are strongly inclined to doubt.
Indeed, this remark applies to all the grateful illusions respecting
ourselves and others, which will have to be discussed by-and-by. The
impulse to hold to the illusion in spite of critical reflection,
involves the further introspective illusion of taking a state of doubt
for one of assurance. Thus, the weak, flattered man or woman manages to
keep up a sort of fictitious belief in the truth of the words which are
so pleasant to the ear.

It is plain that the external conditions of life impose on the
individual certain habits of feeling which often conflict with his
personal propensities. As a member of society he has a powerful motive
to attribute certain feelings to himself, and this motive acts as a bias
in disturbing his vision of what is actually in his mind. While this
holds good of lighter matters, as that of enjoyment just referred to, it
applies still more to graver matters. Thus, for example, a man may
easily persuade himself that he feels a proper sentiment of indignation
against a perpetrator of some mean or cruel act, when as a matter of
fact his feeling is much more one of compassion for the previously liked
offender. In this way we impose on ourselves, disguising our real
sentiments by a thin veil of make-believe.

So far I have spoken of an illusion of introspection as analogous to
the slight misapprehensions of sense-impression which were touched on in
connection with illusions of sense (Chapter III.). It is to be observed,
however, that the confusing of elements of consciousness, which is so
prominent a factor in introspective illusion, involves a species of
error closely analogous to a complete illusion of perception, that is to
say, one which involves a misinterpretation of a sense-impression.

This variety of illusion is illustrated in the case in which a present
feeling or thought is confounded with some inference based on it. For
example, a present thought may, through forgetfulness, be regarded as a
new discovery. Its originality appears to be immediately made known in
the very freshness which characterizes it. Every author probably has
undergone the experience of finding that ideas which started up to his
mind as fresh creations, were unconscious reminiscences of his own or of
somebody else's ideas.

In the case of present emotional states this liability to confuse the
present and the past is far greater. Here there is something hardly
distinguishable from an active illusion of sense-perception. In this
condition of mind a man often says that he has an "intuition" of
something supposed to be immediately given in the feeling itself. For
instance, one whose mind is thrilled by the pulsation of a new joy
exclaims, "This is the happiest moment of my life," and the assurance
seems to be contained in the very intensity of the feeling itself. Of
course, cool reflection will tell him that what he affirms is merely a
belief, the accuracy of which presupposes processes of recollection and
judgment, but to the man's mind at the moment the supremacy of this
particular joy is immediately intuited. And so with the assurance that
the present feeling, for example of love, is undying, that it is equal
to the most severe trials, and so on. A man is said to _feel_ at the
moment that it is so, though as the facts believed have reference to
absent circumstances and events, it is plain that the knowledge is by no
means intuitive.

At such times our minds are in a state of pure feeling: intellectual
discrimination and comparison are no longer possible. In this way our
emotions in the moments of their greatest intensity carry away our
intellects with them, confusing the region of pure imagination with that
of truth and certainty, and even the narrow domain of the present with
the vast domain of the past and future. In this condition differences of
present and future may be said to disappear and the energy of the
emotion to constitute an immediate assurance of its existence

The great region for the illustration of these active illusions is that
of the moral and religious life. With respect to our real motives, our
dominant aspirations, and our highest emotional experiences, we are
greatly liable to deceive ourselves. The moralist and the theologian
have clearly recognized the possibilities of self-deception in matters
of feeling and impulse. To them it is no mystery that the human heart
should mistake the fictitious for the real, the momentary and evanescent
for the abiding. And they have recognized, too, the double bias in these
errors, namely, the powerful disposition to exaggerate the intensity and
persistence of a present feeling on the one hand, and on the other hand
to take a mere wish to feel in a particular way for the actual
possession of the feeling.

_Philosophic Illusions._

The opinion of theologians respecting the nature of moral introspection
presents a singular contrast to that entertained by some philosophers as
to the nature of self-consciousness. It is supposed by many of these
that in interrogating their internal consciousness they are lifted above
all risk of error. The "deliverance of consciousness" is to them
something bearing the seal of a supreme authority, and must not be
called in question. And so they make an appeal to individual
consciousness a final resort in all matters of philosophical dispute.

Now, on the face of it, it does not seem probable that this operation
should have an immunity from all liability to error. For the matters
respecting which we are directed to introspect ourselves, are the most
subtle and complex things of our intellectual and emotional life. And
some of these philosophers even go so far as to affirm that the plain
man is quite equal to the niceties of this process.

It has been brought as a charge against some of these same philosophers
that they have based certain of their doctrines on errors of
introspection. This charge must, of course, be received with some sort
of suspicion here, since it has been brought forward by avowed disciples
of an opposite philosophic school. Nevertheless, as there is from our
present disinterested and purely scientific point of view a presumption
that philosophers like other men are fallible, and since it is certain
that philosophical introspection does not materially differ from other
kinds, it seems permissible just to glance at some of these alleged
illusions in relation to other and more vulgar forms. Further reference
to them will be made at the end of our study.

These so-called philosophical illusions will be found, like the vulgar
ones just spoken of, to illustrate the distinction drawn between passive
and active illusions. That is to say, the alleged misreading of
individual consciousness would result now from a confusion of distinct
elements, including wrong suggestion, due to the intricacies of the
phenomena, now from a powerful predisposition to read something into the

A kind of illusion in which the passive element seems most conspicuous
would be the error into which the interrogator of the individual
consciousness is said to fall respecting simple unanalyzable states of
mind. On the face of it, it is not likely that a mere inward glance at
the tangle of conscious states should suffice to determine what is such
a perfectly simple mental phenomenon. Accordingly, when a writer
declares that an act of introspection demonstrates the simple
unanalyzable character of such a feeling as the sentiment of beauty or
that of moral approval, the opponent of this view clearly has some show
of argument for saying that this simplicity may be altogether illusory
and due to the absence of a perfect act of attention. Similarly, when it
is said that the idea of space contains no representations of muscular
sensation, the statement may clearly arise from the want of a
sufficiently careful kind of introspective analysis.[105]

In most cases of these alleged philosophical errors, however, the active
and passive factors seem to combine. There are certain intricacies in
the mental phenomenon itself favouring the chances of error, and there
are independent predispositions leading the mind to look at the
phenomenon in a wrong way. This seems to apply to the famous declaration
of a certain school of thinkers that by an act of introspection we can
intuit the fact of liberty, that is to say, a power of spontaneous
determination of action superior to and regulative of the influence of
motives. It may be plausibly contended that this idea arises partly
from a mixing up of facts of present consciousness with inferences from
them, and partly from a natural predisposition of the mind to invest
itself with this supreme power of absolute origination.[106]

In a similar way, it might be contended that other famous philosophic
dicta are founded on a process of erroneous introspection of subjective
mental states. In some cases, indeed, it seems a plausible explanation
to regard these illusions as mere survivals in attenuated shadowy form
of grosser popular illusions. But this is not yet the time to enter on
these, which, moreover, hardly fall perhaps under our definition of an
illusion of introspection.

_Value of the Introspective Method._

In drawing up this rough sketch of the illusions of introspection, I
have had no practical object in view. I have tried to look at the facts
as they are apart from any conclusions to be drawn from them. The
question how far the liability to error in any region of inquiry
vitiates the whole process is a difficult one; and the question whether
the illusions to which we are subject in introspection materially affect
the value of self-knowledge as a whole and consequently of the
introspective method in psychology, as many affirm, is too subtle a one
to be fully treated now. All that I shall attempt here is to show that
it does not do this any more than the risk of sense-illusion can be said
materially to affect the value of external observation.

It is to be noted first of all that the errors of introspection are much
more limited than those of sense-perception. They broadly answer to the
slight errors connected with the discrimination and recognition of the
sense-impression. There is nothing answering to a complete hallucination
in the sphere of the inner mental life. It follows, too, from what has
been said above, that the amount of active error in introspection is
insignificant, since the representation of a feeling or belief is so
very similar to the actual experience of it.

In brief, the errors of introspection, though numerous, are all too
slight to render the process of introspection as a whole unsound and
untrustworthy. Though, as we have seen, it involves, strictly speaking,
an ingredient of representation, this fact does not do away with the
broad distinction between presentative and representative cognition.
Introspection is presentative in the sense that the reality constituting
the object of cognition, the mind's present feeling, is as directly
present to the knowing mind as anything can be conceived to be. It may
be added that the power of introspection is a comparatively new
acquisition of the human race, and that, as it improves, the amount of
error connected with its operation may reasonably be expected to become

It is often supposed by those who undervalue the introspective method in
psychology that there is a special difficulty in the detection of error
in introspection, owing to the fact that the object of inspection is
something individual and private, and not open to common scrutiny as the
object of external perception. Yet, while allowing a certain force to
this objection I would point out, first of all, that even in
sense-perception, what the individual mind is immediately certain of is
its own sensations. The relatively perfect certainty which finally
attaches to the presentative side of sense-perception is precisely that
which finally attaches to the results of introspection.

In the second place, it may be said that the contrast between the inner
and the outer experience is much less than it seems. In many cases our
emotions are the direct result of a common external cause, and even when
they are not thus attached to some present external circumstance, we are
able, it is admitted, by the use of language, roughly to compare our
individual feelings. And such comparison is continually bringing to
light the fact that there is a continuity in our mental structure, that
our highest thoughts and emotions lead us back to our common
sense-impressions, and that consequently, in spite of all individual
differences of temperament and mental organization, our inner experience
is in all its larger features a common experience.

I may add that this supposition of the common nature of our internal
experience, as a whole, not only underlies the science of psychology,
but is implied in the very process of detecting and correcting errors of
introspection. I do not mean that in matters of feeling "authority" is
to override "private judgment." Our last resort with respect to things
of the mind is, as I have said, that of careful self-inspection. And the
progress of psychology and the correction of illusion proceed by means
of an ever-improving exercise of the introspective faculty. Yet such
individual inspection can at least be _guided_ by the results of others'
similar inspection, and should be so guided as soon as a general
consensus in matters of internal experience is fairly made out. In point
of fact, the preceding discussion of illusions of introspection has
plainly rested on the sufficiently verified assumption that the calmest
and most efficient kind of introspection, in bringing to light what is
permanent as compared with what is variable in the individual cognition,
points in the direction of a common body of introspected fact.



Besides the perception of external objects, and the inspection of our
internal mental states, there are other forms of quasi-presentative
cognition which need to be touched on here, inasmuch as they are
sometimes erroneous and illusory.

In the last chapter I alluded to the fact that emotion may arise as the
immediate accompaniment of a sense-impression. When this is the case
there is a disposition to read into the external object a quality
answering to the emotion, just as there is a disposition to ascribe to
objects qualities of heat and cold answering to the sensations thus
called. And such a reference of an emotional result to an external
exciting cause approximates in character to an immediate intuition. The
cognition of the quality is instantaneous, and quite free from any
admixture of conscious inference. Accordingly, we have to inquire into
the illusory forms of such intuition, if such there be.

_Æsthetic Intuition._

Conspicuous among these quasi-presentative emotional cognitions is
æsthetic intuition, that is to say, the perception of an object as
beautiful. It is not necessary here to raise the question whether there
is, strictly speaking, any quality in things answering to the sentiment
of beauty in our minds: this is a philosophical and not a psychological
question, and turns on the further question, what we mean by object. All
that we need to assume here is that there are certain aspects of
external things, certain relations of form, together with a power of
exciting certain pleasurable ideas in the spectator's mind, which are
commonly recognized as the cause of the emotion of beauty, and indeed
regarded as constituting the embodiments of the objective quality,
beauty. Æsthetic intuition thus clearly implies the immediate assurance
of the existence of a common source of æsthetic delight, a source bound
up with an object of common sense-perception. And so we may say that to
call a thing beautiful is more or less distinctly to recognize it as a
cause of a present emotion, and to attribute to it a power of raising a
kindred emotion in other minds.

_Æsthetic Illusion._

According to this view of the matter, an illusion of æsthetic intuition
would arise whenever this power of affecting a number of minds
pleasurably is wrongly attributed, by an act of "intuition," to an
object of sense-perception, on the ground of a present personal

Now, this error is by no means unfrequent. Our delight in viewing
external things, though agreeing up to a certain point, does not agree
throughout. It is a trite remark that there is a large individual
factor, a considerable "personal equation," in matters of taste, as in
other matters. Permanent differences of natural sensibility, of
experience, of intellectual habits, and so on, make an object
æsthetically impressive and valuable to one man and not to another. Yet
these differences tend to be overlooked. The individual mind, filled
with delight at some spectacle, automatically projects its feeling
outwards in the shape of a cause of a common sentiment. And the force of
this impulse cannot be altogether explained as the effect of past
experiences and of association. It seems to involve, in addition, the
play of social instincts, the impulse of the individual mind to connect
itself in sympathy with the collective mind.

Here, as in the other varieties of illusion already treated of, we may
distinguish between a passive and an active side; only in this case the
passive side must not be taken as corresponding to any common
suggestions of the object, as in the case of perception proper. So far
as an illusion of æsthetic intuition may be considered as passive, it
must be due to the effect of circumscribed individual associations with
the object.

All agree that what is called beauty consists, to a considerable extent,
of a power of awaking pleasant suggestions, but in order that these
should constitute a ground of æsthetic value, they must be common,
participated in by all, or at least by an indefinite number. This will
be the case when the association rests on our common every-day
experiences, and our common knowledge of things, as in the case of the
peaceful beauty of an ascending curl of blue smoke in a woody landscape,
or the awful beauty of a lofty precipice. On the other hand, when the
experience and recollections, which are the source of the pleasure, are
restricted and accidental, any attribution of objective worth is
illusory. Thus, the ascription of beauty to one's native village, to
one's beloved friends, and so on, in so far as it carries the conviction
of objective worth, may imply a confusion of the individual with the
common experience.

The active side of this species of illusions would be illustrated in
every instance of ascribing beauty to objects which is due, in a
considerable measure at least, to some pre-existing disposition in the
mind, whether permanent or temporary. A man brings his peculiar habits
of thought and feeling to the contemplation of objects, and the æsthetic
impression produced is coloured by these predispositions. Thus, a person
of a sad and gloomy cast of mind will be disposed to see a sombre beauty
where other eyes see nothing of the kind. And then there are all the
effects of temporary conditions of the imagination and the feelings.
Thus, the individual mind may be focussed in a certain way through the
suggestion of another. People not seldom see a thing to be beautiful
because they are told that it is so. It might not be well to inquire too
curiously how many of the frequenters of the annual art exhibitions use
their own eyes in framing their æsthetic judgments. Or the temporary
predisposition may reside in a purely personal feeling or desire
uppermost at the time. Our enjoyment of nature or of art is coloured by
our temporary mood. There are moments of exceptional mental
exhilaration, when even a commonplace scene will excite an appreciable
kind of admiration. Or there may be a strong wish to find a thing
beautiful begotten of another feeling. Thus, a lover desires to find
beauty in his mistress; or, having found it in her face and form,
desires to find a harmonious beauty in her mind. In these different ways
temporary accidents of personal feeling and imagination enter into and
determine our æsthetic intuition, making it deviate from the common
standard. This kind of error may even approximate in character to an
hallucination of sense when there is nothing answering to a common
source of æsthetic pleasure. Thus, the fond mother, through the very
force of her affection, will construct a beauty in her child, which for
others is altogether non-existent.

What applies to the perception of beauty in the narrow sense will apply
to all other modes of æsthetic intuition, as that of the sublime and the
ludicrous, and the recognition of the opposite of beauty or the ugly. In
like manner, it will apply to moral intuition in so far as it is an
instantaneous recognition of a certain quality in a perceived action
based on, or at least conjoined with, a particular emotional effect. In
men's intuitive judgments respecting the right and the wrong, the noble
and base, the admirable and contemptible, and so on, we may see the same
kind of illusory universalizing of personal feeling as we have seen in
their judgments respecting the beautiful. And the sources of the error
are the same in the two cases. Accidents of experience, giving special
associations to the actions, will not unfrequently warp the individual
intuition. Ethical culture, like æsthetic culture, means a continual
casting aside of early illusory habits of intuition. And further, moral
intuition illustrates all those effects of feeling which we have briefly
traced in the case of æsthetic intuition. The perversions of the moral
intuition under the sway of prejudice are too familiar to need more than
a bare allusion.

_Nature of Insight._

There remains one further mode of cognition which approximates in
character to presentative knowledge, and is closely related to external
perception. I refer to the commonly called "intuitive" process by which
we apprehend the feelings and thoughts of other minds through the
external signs of movement, vocal sound, etc., which make up expression
and language. This kind of knowledge, which is not sufficiently marked
off from external perception on the one side and introspection on the
other, I venture to call Insight.

I am well aware that this interpretation of the mental states of others
is commonly described as a process of inference involving a conscious
reference to our own similar experiences. I willingly grant that it is
often so. At the same time, it must be perfectly plain that it is not
always so. It is, indeed, doubtful whether in its first stages in early
life it is invariably so, for there seem to be good reasons for
attributing to the infant mind a certain degree of instinctive or
inherited capability in making out the looks and tones of others.[107]
And, however this may be, it is certain that with the progress of life a
good part of this interpretation comes to be automatic or unconscious,
approximating in character to a sense-perception. To recognize
contentment in a placid smile is, one would say, hardly less immediate
and intuitive than to recognize the coolness of a stream.

We must, of course, all allow that the fusion of the presentative and
the representative element is, speaking generally, more complete in the
case of sense-perception than in that here considered. In spite of
Berkeley's masterly account of the _rationale_ of visual perception as
an interpretation of "visual language" and all that has confirmed it,
the plain man cannot, at the moment of looking at an object, easily
bring himself to admit that distance is not directly present to his
vision. On the other hand, on cool reflection, he will recognize that
the complacent benevolent sentiment is distinct from the particular
movements and changes in the eye and other features which express it.
Yet, while admitting this, I must contend that there is no very hard and
fast line dividing the two processes, but that the reading of others'
feelings approximates in character to an act of perception.

An intuitive insight may, then, be defined as that instantaneous,
automatic, or "unconscious" mode of interpreting another's feeling
which occurs whenever the feeling is fully expressed, and when its signs
are sufficiently familiar to us. This definition will include the
interpretation of thoughts by means of language, though not, of course,
the belief in an objective fact grounded on a recognition of another's
belief. On the other hand, it will exclude all the more complex
interpretations of looks and words which imply conscious comparison,
reflection, and reasoning. Further, it will exclude a large part of the
interpretation of actions as motived, since this, though sometimes
approaching the intuitive form, is for the most part a process of
conjectural or doubtful inference, and wanting in the immediate
assurance which belongs to an intuitive reading of a present emotion or

From this short account of the process of insight, its relation to
perception and introspection becomes pretty plain. On the one hand, it
closely resembles sense-perception, since it proceeds by the
interpretation of a sense-impression by means of a representative image.
On the other hand, it differs from sense-perception, and is more closely
allied to introspection in the fact that, while the process of
interpretation in the former case is a reconstruction of _external_
experiences, in the latter case it is a reconstruction of _internal_
experiences. To intuit another's feeling is clearly to represent to
ourselves a certain kind of internal experience previously known, in its
elements at least, by introspection, while these represented experiences
are distinctly referred to another personality.

And now we see what constitutes the object of insight. This is, in part,
a common experience, as in the case of sense-perception and æsthetic
intuition, since to perceive another's feeling is implicitly to cognize
the external conditions of a common insight. But this is clearly not the
whole, nor even the main part of objective reality in this act of
cognition. An intuitive insight differs from a sense-perception in that
it involves an immediate assurance of the existence of a feeling
presentatively known, though not to our own minds. The object in insight
is thus a presentative feeling as in introspection, though not our own,
but another's. And so it differs from the object in sense-perception in
so far as this last involves sense-experiences, as muscular and tactual
feelings, which are not _at the moment_ presentatively known to any

_Illusions of Insight._

And now we are in a position, perhaps, to define an illusion of insight,
and to inquire whether there is anything answering to our definition. An
illusory insight is a quasi-intuition of another's feelings which does
not answer to the internal reality as presentatively known to the
subject himself. In spite of the errors of introspection dealt with in
the last chapter, nobody will doubt that, when it is a question between
a man's knowing what is at the moment in his own mind and somebody
else's knowing, logic, as well as politeness, requires us to give
precedence to the former.

An illusion of insight, like the other varieties of illusion already
dealt with, may arise either by way of wrong suggestion or by way of a
warping preconception. Let us look at each of these sources apart.

Our insights, like our perceptions, though intuitive in form, are
obviously determined by previous experience, association, and habit.
Hence, on its passive side, an illusion of insight may be described as a
wrong interpretation of a new or exceptional case. For example, having
associated the representation of a slight feeling of astonishment with
uplifted eyebrows, we irresistibly tend to see a face in which this is a
constant feature as expressing this particular shade of emotion. In this
way we sometimes fall into grotesque errors as to mental traits. And the
most practised physiognomist may not unfrequently err by importing the
results of his special circle of experiences into new and unlike cases.

Much the same thing occurs in language. Our timbre of voice, our
articulation, and our vocabulary, like our physiognomy, have about them
something individual, and error often arises from overlooking this, and
hastily reading common interpretations into exceptional cases. The
misunderstandings that arise even among the most open and confiding
friends sufficiently illustrate this liability to error.

Sometimes the error becomes more palpable, as, for example, when we
visit another country. A foreign language, when heard, provokingly
suggests all kinds of absurd meanings through analogies to our familiar
tongue. Thus, the Englishman who visits Germany cannot, for a time, hear
a lady use the expression, "Mein Mann," without having the amusing
suggestion that the speaker is wishing to call special attention to the
fact of her husband's masculinity. And doubtless the German who visits
us derives a similar kind of amusement from such involuntary

A fertile source of illusory insight is, of course, conscious deception
on the part of others. The rules of polite society require us to be
hypocrites in a small way, and we have occasionally to affect the signs
of amiability, interest, and amusement, when our actual sentiment is one
of indifference, weariness, or even positive antipathy. And in this way
a good deal of petty illusion arises. Although we may be well aware of
the general untrustworthiness of this society behaviour, such is the
force of association and habit, that the bland tone and flattering word
irresistibly excite a momentary feeling of gratification, an effect
which is made all the more easy by the co-operation of the recipient's
own wishes, touched on in the last chapter.

Among all varieties of this deception, that of the stage is the most
complete. The actor is a man who has elaborately trained himself in the
simulation of certain feelings. And when his acting is of the best
quality, and the proper bodily attitude, gesture, tone of voice, and so
on, are hit off, the force of the illusion completely masters us. For
the moment we lose sight of the theatrical surroundings, and see the
actor as really carried away by the passion which he so closely
imitates. Histrionic illusion is as complete as any artistic variety can
venture to be.[108]

I have said that our insights are limited by our own mental experience,
and so by introspection. In truth, every interpretation of another's
look and word is determined ultimately, not by what we have previously
observed in others, but by what we have personally felt, or at least
have in a sense made our own by intense sympathy. Hence we may, in
general, regard an illusion of insight on the active side as a hasty
projection of our own feelings, thoughts, etc., into other minds.

We habitually approach others with a predisposition to attribute to them
our own modes of thinking and feeling. And this predisposition will be
the more powerful, the more desirous we are for sympathy, and for that
confirmation of our own views which the reflection of another mind
affords. Thus, when making a new acquaintance, people are in general
disposed to project too much of themselves into the person who is the
object of inspection. They intuitively endow him with their own ideas,
ways of looking at things, prejudices of sentiment, and so on, and
receive something like a shock when later on they find out how different
he is from this first hastily formed and largely performed image.

The same thing occurs in the reading of literature, and the appreciation
of the arts of expression generally. We usually approach an author with
a predisposition to read our own habits of thought and sentiment into
his words. It is probably a characteristic defect of a good deal of
current criticism of remote writers to attribute to them too much of our
modern conceptions and aims. Similarly, we often import our own special
feelings into the utterances of the poet and of the musical composer.
That much of this intuition is illusory, may be seen by a little
attention to the "intuitions" of different critics. Two readers of
unlike emotional organization will find incompatible modes of feeling in
the same poet. And everybody knows how common it is for musical critics
and amateurs to discover quite dissimilar feelings in the same

The effect of this active projection of personal feeling will, of
course, be seen most strikingly when there is a certain variety of
feeling actually excited at the time in the observer's mind. A man who
is in a particularly happy mood tends to reflect his exuberant gladness
on others. The lover, in the moment of exalted emotion, reads a response
to all his aspirations in his mistress's eyes. Again, a man will tend to
project his own present ideas into the minds of others, and so imagine
that they know what he knows; and this sometimes leads to a comical kind
of embarrassment, and even to a betrayal of something which it was the
interest of the person to keep to himself. Once more, in interpreting
language, we may sometimes catch ourselves mistaking the meaning, owing
to the presence of a certain idea in the mind at the time. Thus, if I
have just been thinking of Comte, and overhear a person exclaim, "I'm
positive," I irresistibly tend, for the moment, to ascribe to him an
avowal of discipleship to the great positivist.

_Poetic Illusion._

The most remarkable example of this projection of feeling is
undoubtedly illustrated in the poetic interpretation of inanimate
nature. The personification of tree, mountain, ocean, and so on,
illustrates, no doubt, the effect of association and external
suggestion; for there are limits to such personification. But
resemblance and suggestion commonly bear, in this case, but a small
proportion to active constructive imagination. One might, perhaps, call
this kind of projection the hallucination of insight, since there is
nothing objective corresponding to the interpretative image.

The imaginative and poetic mind is continually on the look out for hints
of life, consciousness, and emotion in nature. It finds a certain kind
of satisfaction in this half-illusory, dream-like transformation of
nature. The deepest ground of this tendency must probably be looked for
in the primitive ideas of the race, and the transmission by inheritance
of the effect of its firmly fixed habits of mind. The undisciplined mind
of early man, incapable of distinguishing the object of perception from
the product of spontaneous imagination, and taking his own double
existence as the type of all existence, actually saw the stream, the
ocean, and the mountain as living beings; and so firmly rooted is this
way of regarding objects, that even our scientifically trained minds
find it a relief to relapse occasionally into it.[110]

While there is this general imaginative disposition in the poetic mind
to endow nature with life and consciousness, there are special
tendencies to project the individual feelings into objects. Every
imaginative mind looks for reflections of its own deepest feelings in
the world about it. The lonely embittered heart, craving for sympathy,
which he cannot meet with in his fellow-man, finds traces of it in the
sighing of the trees or the moaning of the sad sea-wave. Our Poet
Laureate, in his great elegy, has abundantly illustrated this impulse of
the imagination to reflect its own emotional colouring on to inanimate
things: for example in the lines--

    "The wild unrest that lives in woe
  Would dote and pore on yonder cloud
  That rises upward always higher,
     And onward drags a labouring breast,
     And topples round the dreary west,
  A looming bastion fringed with fire."

So far I have been considering active illusions of insight as arising
through the play of the impulse of the individual mind to project its
feelings outwards, or to see their reflections in external things. I
must now add that active illusion may be due to causes similar to those
which we have seen to operate in the sphere of illusory perception and
introspection. That is to say, there may be a disposition, permanent or
temporary, to ascribe a certain kind of feeling to others in accordance
with our wishes, fears, and so on.

To give an illustration of the permanent causes, it is well known that a
conceited man will be disposed to attribute admiration of himself to
others. On the other hand, a shy, timid person will be prone to read
into other minds the opposite kind of feeling.

Coming to temporary forces, we find that any expectation to meet with a
particular kind of mental trait in a new acquaintance will dispose the
observer hastily and erroneously to attribute corresponding feelings to
the person. And if this expectation springs out of a present feeling,
the bias to illusory insight is still more powerful. For example, a
child that fears its parent's displeasure will be prone to misinterpret
the parent's words and actions, colouring them according to its fears.
So an angry man, strongly desirous of making out that a person has
injured him, will be disposed to see signs of conscious guilt in this
person's looks or words. Similarly, a lover will read fine thoughts or
sentiments into the mind of his mistress under the influence of a strong
wish to admire.

And what applies to the illusory interpretation of others' feelings
applies to the ascription of feelings to inanimate objects. This is due
not simply to the impulse to expand one's conscious existence through
far-reaching resonances of sympathy, but also to a permanent or
temporary disposition to attribute a certain kind of feeling to an
object. Thus, the poet personifies nature in part because his emotional
cravings prompt him to construct the idea of something that can be
admired or worshipped. Once more, the action of a momentary feeling when
actually excited is seen in the "mechanical" impulse of a man to
retaliate when he strikes his foot against an object, as a chair, which
clearly involves a tendency to attribute an intention to hurt to the
unoffending body, and the _rationale_ of which odd procedure is pretty
correctly expressed in the popular phrase: "It relieves the feelings."

It is worth noting, perhaps, that these illusions of insight, like those
of perception, may involve an inattention to the actual impression of
the moment. To erroneously attribute a feeling to another through an
excess of sympathetic eagerness is often to overlook what a perfectly
dispassionate observer would see, as, for example, the immobility of the
features or the signs of a deliberate effort to simulate. This
inattention will, it is obvious, be greatest in the poetic attribution
of life and personality to natural objects, in so far as this
approximates to a complete momentary illusion. To see a dark overhanging
rock as a grim sombre human presence, is for the moment to view it under
this aspect only, abstracting from its many obvious unlikenesses.

In the same manner, a tendency to read a particular meaning into a word
may lead to the misapprehension of the word. To give an illustration: I
was lately reading the fifth volume of G. H. Lewes's _Problems of Life
and Mind_. In reading the first sentence of one of the sections, I again
and again fell into the error of taking "The great Lagrange," for "The
great Language." On glancing back I saw that the section was headed "On
Language," and I at once recognized the cause of my error in the
pre-existence in my mind of the representative image of the word

In concluding this short account of the errors of insight, I may observe
that their range is obviously much greater than that of the previously
considered classes of presentative illusion. This is, indeed, involved
in what has been said about the nature of the process. Insight, as we
have seen, though here classed with preservative cognition, occupies a
kind of border-land between immediate knowledge or intuition and
inference, shading off from the one to the other. And in the very nature
of the case the scope for error must be great. Even overlooking human
reticence, and, what is worse, human hypocrisy, the conditions of an
accurate reading of others' minds are rarely realized. If, as has been
remarked by a good authority, one rarely meets, even among intelligent
people, with a fairly accurate observer of external things, what shall
be said as to the commonly claimed power of "intuitive insight" into
other people's thoughts and feelings, as though it were a process above
suspicion? It is plain, indeed, on a little reflection, that, taking
into account what is required in the way of large and varied experience
(personal and social), a habit of careful introspection, as well as a
habit of subtle discriminative attention to the external signs of mental
life, and lastly, a freedom from prepossession and bias, only a very few
can ever hope even to approximate to good readers of character.

And then we have to bear in mind that this large amount of error is apt
to remain uncorrected. There is not, as in the case of external
perception, an easy way of verification, by calling in another sense; a
misapprehension, once formed, is apt to remain, and I need hardly say
that errors in these matters of mutual comprehension have their palpable
practical consequences. All social cohesion and co-operation rest on
this comprehension, and are limited by its degree of perfection. Nay,
more, all common knowledge itself, in so far as it depends on a mutual
communication of impressions, ideas, and beliefs, is limited by the
fact of this great liability to error in what at first seems to be one
of the most certain kinds of knowledge.

In view of this depressing amount of error, our solace must be found in
the reflection that this seemingly perfect instrument of intuitive
insight is, in reality, like that of introspection, in process of being
fashioned. Mutual comprehension has only become necessary since man
entered the social state, and this, to judge by the evolutionist's
measure of time, is not so long ago. A mental structure so complex and
delicate requires for its development a proportionate degree of
exercise, and it is not reasonable to look yet for perfect precision of
action. Nevertheless, we may hope that, with the advance of social
development, the faculty is continually gaining in precision and
certainty. And, indeed, this hope is already assured to us in the fact
that the faculty has begun to criticise itself, to distinguish between
an erroneous and a true form of its-operation. In fact, all that has
been here said about illusions of insight has involved the assumption
that intellectual culture sharpens the power and makes it less liable to



Thus far we have been dealing with Presentative Illusions, that is to
say, with the errors incident to the process of what may roughly be
called presentative cognition. We have now to pass to the consideration
of Representative Illusion, or that kind of error which attends
representative cognition in so far as it is immediate or
self-sufficient, and not consciously based on other cognition. Of such
immediate representative cognition, memory forms the most conspicuous
and most easily recognized variety. Accordingly, I proceed to take up
the subject of the Illusions of Memory.[111]

The mystery of memory lies in the apparent immediateness of the mind's
contact with the vanished past. In "looking back" on our life, we seem
to ourselves for the moment to rise above the limitations of time, to
undo its work of extinction, seizing again the realities which its
on-rushing stream had borne far from us. Memory is a kind of
resurrection of the buried past: as we fix our retrospective glance on
it, it appears to start anew into life; forms arise within our minds
which, we feel sure, must faithfully represent the things that were. We
do not ask for any proof of the fidelity of this dramatic representation
of our past history by memory. It is seen to be a faithful imitation,
just because it is felt to be a revival of the past. To seek to make the
immediate testimony of memory more sure seems absurd, since all our ways
of describing and illustrating this mental operation assume that in the
very act of performing it we do recover a part of our seemingly "dead

To challenge the veracity of a person's memory is one of the boldest
things one can do in the way of attacking deep-seated conviction. Memory
is the peculiar domain of the individual. In going back in recollection
to the scenes of other years he is drawing on the secret store-house of
his own consciousness, with which a stranger must not intermeddle. To
cast doubt on a person's memory is commonly resented as an impertinence,
hardly less rude than to question his reading of his own present mental
state. Even if the challenger professedly bases his challenge on the
testimony of his own memory, the challenged party is hardly likely to
allow the right of comparing testimonies. He can in most cases boldly
assert that those who differ from him are lacking in _his_ power of
recollection. The past, in becoming the past, has, for most people,
ceased to be a common object of reference; it has become a part of the
individual's own inner self, and cannot be easily dislodged or shaken.

Yet, although people in general are naturally disposed to be very
confident about matters of recollection, reflective persons are pretty
sure to find out, sooner or later, that they occasionally fall into
errors of memory. It is not the philosopher who first hints at the
mendacity of memory, but the "plain man" who takes careful note of what
really happens in the world of his personal experience. Thus, we hear
persons, quite innocent of speculative doubt, qualifying an assertion
made on personal recollection by the proviso, "unless my memory has
played me false." And even less reflective persons, including many who
pride themselves on their excellent memory, will, when sorely pressed,
make a grudging admission that they may, after all, be in error. Perhaps
the weakest degree of such an admission, and one which allows to the
conceding party a semblance of victory, is illustrated in the "last
word" of one who has boldly maintained a proposition on the strength of
individual recollection, but begins to recognize the instability of his
position: "I either witnessed the occurrence or dreamt it." This is
sufficient to prove that, with all people's boasting about the
infallibility of memory, there are many who have a shrewd suspicion that
some of its asseverations will not bear a very close scrutiny.

_Psychology of Memory._

In order to understand the errors of memory, we must proceed, as in the
case of illusions of perception, by examining a little into the nature
of the normal or correct process.

An act of recollection is said by the psychologist to be purely
representative in character, whereas perception is partly
representative, partly preservative. To recall an object to the mind is
to reconstruct the percept in the absence of a sense-impression.[112]

An act of memory is obviously distinguished from one of simple
imagination by the presence of a conscious reference to the past. Every
recollection is an immediate reapprehension of some past object or
event. However vague this reference may be, it must be there to
constitute the process one of recollection.

The every-day usages of language do not at first sight seem to
consistently observe this distinction. When a boy says, "I remember my
lesson," he appears to be thinking of the present only, and not
referring to the past. In truth, however, there is a vague reference to
the fact of retaining a piece of knowledge through a given interval of

Again, when a man says, "I recollect your face," this means, "Your face
seems familiar to me." Here again, though there is no definite reference
to the past, there is a vague and indefinite one.

It is plain from this definition that recollection is involved in all
recognition or identification. Merely to be aware that I have seen a
person before implies a minimum exercise of memory. Yet we may roughly
distinguish the two actions of perception and recollection in the
process of recognition. The mere recognition of an object does not
imply the presence of a distinct representative or mnemonic image. In
point of fact, in so far as recognition is assimilation, it cannot be
said to imply a _distinct_ act of memory at all. It is only when
similarity is perceived amid difference, only when the accompaniments or
surroundings of the object as previously seen, differencing it from the
object as now seen, are brought up to the mind that we may be said
distinctly to recall the past. And our state of mind in recognizing an
object or person is commonly an alternation between these two acts of
separating the mnemonic image from the percept and so recalling or
recollecting the past, and fusing the image and the percept in what is
specifically marked off as recognition.[113]

Although I have spoken of memory as a reinstatement in representative
form of external experience, the term must be understood to include
every revival of a past experience, whether external or internal, which
is recognized as a revival. In a general way, the recallings of our
internal feelings take place in close connection with the recollection
of external circumstances or events, and so they may be regarded as
largely conditioned by the laws of this second kind of reproduction.

The old conceptions of mind, which regarded every mental phenomenon as a
manifestation of an occult spiritual substance, naturally led to the
supposition that an act of recollection involves the continued,
unbroken existence of the reproductive or mnemonic image in the hidden
regions of the mind. To recollect is, according to this view, to draw
the image out of the dark vaults of unconscious mind into the upper
chamber of illumined consciousness.

Modern psychology recognizes no such pigeonhole apparatus in unconscious
mind. On the purely psychical side, memory is nothing but an occasional
reappearance of a past mental experience. And the sole mental conditions
of this reappearance are to be found in the circumstances of the moment
of the original experience and in those of the moment of the

Among these are to be specially noted, first of all, the degree of
impressiveness of the original experience, that is to say, the amount of
interest it awakened and of attention it excited. The more impressive
any experience, the greater the chances of its subsequent revival.
Moreover, the absence of impressiveness in the original experience may
be made good either by a repetition of the actual experience or, in the
case of non-recurring experiences, by the fact of previous mnemonic

In the second place, the pre-existing mental states at the time of
revival are essential conditions. It is now known that every
recollection is determined by some link of association, that every
mnemonic image presents itself in consciousness only when it has been
preceded by some other mental state, presentative or representative,
which is related to the image. This relation may be one of contiguity,
that is to say, the original experiences may have occurred at the same
time or in close succession; or one of similarity (partial and not
amounting to identity), as where the sight of one place or person
recalls that of another place or person. Finally, it is to be observed
that recollection is often an act, in the full sense of that term,
involving an effort of voluntary attention at the moment of revival.

Modern physiology has done much towards helping us to understand the
nervous conditions of memory. The biologist regards memory as a special
phase of a universal property of organic structure, namely,
modifiability by the exercise of function, or the survival after any
particular kind of activity of a disposition to act again in that
particular way. The revival of a mental impression in the weaker form of
an image is thus, on its physical side, due in part to this remaining
functional disposition in the central nervous tracts concerned. And so,
while on the psychical or subjective side we are unable to find anything
permanent in memory, on the physical or objective side we do find such a
permanent substratum.

With respect to the special conditions of mnemonic revival at any time,
physiology is less explicit. In a general way, it informs us that such a
reinstatement of the past is determined by the existence of certain
connections between the nervous structures concerned in the reviving and
revived mental elements. Thus, it is said that when the sound of a name
calls up in the mind a visual image of a person seen some time since, it
is because connections have been formed between particular regions and
modes of activity of the auditory and the visual centres. And it is
supposed that the existence of such connections is somehow due to the
fact that the two regions acted simultaneously in the first instance,
when the sight of the person was accompanied by the hearing of his name.
In other words, the centres, as a whole, will tend to act at any future
moment in the same complex way in which they have acted in past moments.

All this is valuable hypothesis so far as it goes, though it plainly
leaves much unaccounted for. As to why this reinstatement of a total
cerebral pulsation in consequence of the re-excitation of a portion of
the same should be accompanied by the specific mode of consciousness
which we call recollection of something past, it is perhaps unreasonable
to ask of physiology any sort of explanation.[114]

Thus far as to the general or essential characteristics of memory on its
mental and its bodily side. But what we commonly mean by memory is, on
its psychical side at least, much more than this. We do not say that we
properly recollect a thing unless we are able to refer it to some more
or less clearly defined region of the past, and to localize it in the
succession of experiences making up our mental image of the past. In
other words, though we may speak of an imperfect kind of recollection
where this definite reference is wanting, we mean by a perfect form of
memory something which includes this reference.

Without entering just now upon a full analysis of what this reference to
a particular region of the past means, I may observe that it takes place
by help of an habitual retracing of the past, or certain portions of it,
that is to say, a regressive movement of the imagination along the lines
of our actual experience. Setting out from the present moment, I can
move regressively to the preceding state of consciousness, to the
penultimate, and so on. The fact that each distinct mental state is
continuous with the preceding and the succeeding, and in a certain sense
overlaps these, makes any portion of our experience essentially a
succession of states of consciousness, involving some rudimentary idea
of time. And thus, whether I anticipate a future event or recall a past
one, my imagination, setting out from the present moment, constructs a
sequence of experiences of which the one particularly dwelt on is the
other term or boundary. And our idea of the position of this last in
time, like that of an object in space, is one of a relation to our
present position, and is determined by the length of the sequence of
experiences thus run over by the imagination.[115] It may be added that
since the imagination can much more easily follow the actual order of
experience than conceive it as reversed, the retrospective act of memory
naturally tends to complete itself by a return movement forwards from
the remembered event to the present moment.

In practice this detailed retracing of successive moments of mental life
is confined to very recent experiences. If I try to localize in time a
remote event, I am content with placing it in relation to a series of
prominent events or landmarks which serves me as a rough scheme of the
past. The formation of such a mnemonic framework is largely due to the
needs of social converse, which proceeds by help of a common standard of
reference. This standard is supplied by those objective, that is to say,
commonly experienced regularities of succession which constitute the
natural and artificial divisions of the years, seasons, months, weeks,
etc. The habit of recurring to these fixed divisional points of the past
renders a return of imagination to any one of them more and more easy. A
man has a definite idea of "a year ago" which the child wants, just
because he has had so frequently to execute that vague regressive
movement by which the idea arises. And though, as our actual point in
time moves forward, the relative position of any given landmark is
continually changing, the change easily adapts itself to that scheme of
time-divisions which holds good for any present point.

Few of our recollections of remote events involve a definite reference
to this system of landmarks. The recollections of early life are, in the
case of most people, so far as they depend on individual memory, very
vaguely and imperfectly localized. And many recent experiences which are
said to be half forgotten, are not referred to any clearly assignable
position in time. One may say that in average cases definite
localization characterizes only such supremely interesting personal
experiences as spontaneously recur again and again to the mind. For the
rest it is confined to those facts and events of general interest to
which our social habits lead us repeatedly to go back.[116]

The consciousness of personal identity is said to be bound up with
memory. That is to say, I am conscious of a continuous permanent self
under all the varying surface-play of the stream of consciousness, just
because I can, by an act of recollection, bring together any two
portions of this stream of experience, and so recognize the unbroken
continuity of the whole. If this is so, it would seem to follow from the
very fragmentary character of our recollections that our sense of
identity is very incomplete. As we shall see presently, there is good
reason to look upon, this consciousness of continuous personal existence
as resting only in part on memory, and mainly on our independently
formed representation of what has happened in the numberless and often
huge lacunæ of the past left by memory.

Having thus a rough idea of the mechanism of memory to guide us, we may
be able to investigate the illusions incident to the process.

_Illusions of Memory._

By an illusion of memory we are to understand a false recollection or a
wrong reference of an idea to some region of the past. It might,
perhaps, be roughly described as a wrong interpretation of a special
kind of mental image, namely, what I have called a mnemonic image.

Mnemonic illusion is thus distinct from mere forgetfulness or imperfect
memory. To forget or be doubtful about a past event is one thing; to
seem to ourselves to remember it when we afterwards find that the fact
was otherwise than we represented it in the apparent act of recollection
is another thing. Indistinctness of recollection, or the decay of
memory, is, as we shall soon see, an important co-operant condition of
mnemonic illusion, but does not constitute it, any more than haziness of
vision or disease of the visual organ, though highly favourable to
optical illusion, can be said to constitute it.

We may conveniently proceed in our detailed examination of illusions of
memory, by distinguishing between three facts which appear to be
involved in every complete and accurate process of recollection. When I
distinctly recall an event, I am immediately sure of three things: (1)
that something did really happen to me; (2) that it happened in the way
I now think; and (3) that it happened when it appears to have happened.
I cannot be said to recall a past event unless I feel sure on each of
these points. Thus, to be able to say that an event happened at a
particular date, and yet unable to describe how it happened, means that
I have a very incomplete recollection. The same is true when I can
recall an event pretty distinctly, but fail to assign it its proper
date. This being so, it follows that there are three possible openings,
and only three, by which errors of memory may creep in. And, as a matter
of fact, each of these openings will be found to let in one class of
mnemonic illusion. Thus we have (1) false recollections, to which there
correspond no real events of personal history; (2) others which
misrepresent the manner of happening of the events; and (3) others which
falsify the date of the events remembered.

It is obvious, from a mere glance at this threefold classification, that
illusions of memory closely correspond to visual illusions. Thus, class
(1) may be likened to the optical illusions known as subjective
sensations of light, or ocular spectra. Here we can prove that there is
nothing actually seen in the field of vision, and that the semblance of
a visible object arises from quite another source than that of ordinary
external light-stimulation, and by what may be called an accident.
Similarly, in the case of the first class of mnemonic illusions, we
shall find that there is nothing actually recollected, but that the
mnemonic spectra or phantoms of recollected objects can be accounted for
in quite another way. Such illusions come nearest to hallucinations in
the region of memory.

Again, class (2) has its visual analogue in those optical illusions
which depend on effects of haziness and of the action of refracting
media interposed between the eye and the object; in which cases, though
there is some real thing corresponding to the perception, this is seen
in a highly defective, distorted, and misleading form. In like manner,
we can say that the images of memory often get obscured, distorted, and
otherwise altered when they have receded into the dim distance, and are
looked back upon through a long space of intervening mental experience.
Finally, class (3) has its visual counterpart in erroneous perceptions
of distance, as when, for example, owing to the clearness of the
mountain atmosphere and the absence of intervening objects, the side of
the Jungfrau looks to the inexperienced tourist at Wengernalp hardly
further than a stone's throw. It will be found that when our memory
falsifies the date of an event, the error arises much in the same way as
a visual miscalculation of distance.

This threefold division of illusions of memory is plainly a rather
superficial one, and not based on distinctions of psychological nature
or origin. In order to make our treatment of the subject scientific as
well as popular, it will be necessary to introduce the distinction
between the passive and the active factor under each head. It will be
found, I think, without forcing the analogy too far, that here, as in
the case of the illusions of perception and introspection, error is
attributable now to misleading suggestion on the part of the mental
content of the moment, now to a process of incorporating into this
content a mental image not suggested by it, but existing independently.

If we are to proceed as we did in the case of the illusions of sense,
and take up the lower stages of error first of all, we shall need to
begin with the third class of errors, those of localization in time, or
of what may be called mnemonic perspective. It has been already observed
that the definite localization of a mnemonic image is only an occasional
accompaniment of what is loosely called recollection. Hence, error as
to the position of an event in the past chain of events would seem to
involve the least degree of violation of the confidence which we are
wont to repose in memory. After this, we may proceed to the discussion
of the second class, which I may call distortions of the mnemonic
picture. And, finally, we may deal with the most signal and palpable
variety of error of memory, namely, the illusions which I have called
mnemonic spectra.

_Illusions of Perspective: A. Definite Localization._

In order to understand these errors of mnemonic perspective, we shall
have to inquire more closely than we have yet done into the
circumstances which customarily determine our idea of the degree of
propinquity or of remoteness of a past event. And first of all, we will
take the case of a complete act of recollection when the mind is able to
travel back along an uninterrupted series of experiences to a definitely
apprehended point. Here there would seem, at first sight, to be no room
for error, since this movement of retrospective imagination may be said
to involve a direct measurement of the distance, just as a sweep of the
eye over the ground between a spectator and an object affords a direct
measurement of the intervening space.

Modern science, however, tells us that this mode of measurement is by no
means the simple and accurate process which it at first seems to be. In
point of fact, there is something like a constant error in all such
retrospective measurement. Vierordt has proved experimentally, by making
a person try to reproduce the varying time-intervals between the
strokes of the pendulum of a metronome, that when the interval is a very
small one, we uniformly tend to exaggerate it in retrospection; when a
large one, to regard it, on the contrary, as less than it actually

A mere act of reflection will convince any one that when he tries to
conceive a very small interval, say a quarter of a second, he is likely
to make it too great. On the other hand, when we try to conceive a year,
we do not fully grasp the whole extent of the duration. This is proved
by the fact that merely by spending more time over the attempt, and so
recalling a larger number of the details of the period, we very
considerably enlarge our first estimate of the duration. And this leads
to great discrepancies in the appreciation of the relative magnitudes of
past sections of time. Thus, as Wundt observes, though in retrospect
both a month and a year seem too short, the latter is relatively much
more shortened than the former.[118]

The cause of this constant error in the mode of reproducing durations
seems to be connected with the very nature of the reproductive act. It
must be borne in mind that this act is itself, like the experience which
it represents, a mental process, occupying time, and that consequently
it may very possibly reflect its time-character on the resulting
judgment. Thus, since it certainly takes more than a quarter of a second
to pass in imagination from one impression to another, it may be that we
tend to confound this duration with that which we try to represent.
Similarly, the fact that in the act of reproductive imagination we
under-estimate a longer interval between two impressions, say those of
the slow beats of a colliery engine, may be accounted for by the
supposition that the imagination tends to pass from the one impression
to the succeeding one too rapidly.[119]

The gross misappreciation of duration of long periods of time, while it
may illustrate the principle just touched on, clearly involves the
effect of other and more powerful influences. A mere glance at what is
in our mind when we recall such a period as a month or a year, shows
that there is no clear concrete representation at all. Time, it has been
often said, is known only so far as filled with concrete contents or
conscious experiences, and a perfect imagination of any particular
period of past time would involve a retracing of all the successive
experiences which have gone to make up this section of our life. This, I
need not say, never happens, both because, on the one hand, memory does
not allow of a complete reproduction of any segment of our experience,
and because, on the other hand, such an imaginative reproduction, even
if possible, would clearly occupy as much time as the experience

When I call up an image of the year just closing, what really happens is
a rapid movement of imagination over a series of prominent events, among
which the succession of seasons probably occupies the foremost place,
serving, as I have remarked, as a framework for my retrospective
picture. Each of the events which I thus run over is really a long
succession of shorter experiences, which, however, I do not separately
represent to myself. My imaginative reproduction of such a period is
thus essentially a greatly abbreviated and symbolic mode of
representation. It by no means corresponds to the visual imagination of
a large magnitude, say that of the length of sea horizon visible at any
one moment, which is complete in an instant, and quite independent of a
successive imagination of its parts or details. It is essentially a very
fragmentary and defective numerical idea, in which, moreover, the real
quantitative value of the units is altogether lost sight of.

Now, it seems to follow from this that there is something illusory in
all our recallings of long periods of the past. It is by no means
strictly correct to say that memory ever reinstates the past. It is more
true to say that we see the past in retrospect as greatly foreshortened.
Yet even this is hardly an accurate account of what takes place, since,
when we look at an object foreshortened in perspective, we see enough to
enable us imaginatively to reconstruct the actual size of the object,
whereas in the case of time-perspective no such reconstruction is even
indirectly possible.

It is to be added that this constant error in time-reproduction is
greater in the case of remote periods than of near ones of the same
length. Thus, the retrospective estimate of a duration far removed from
the present, say the length of time passed at a particular school, is
much more superficial and fragmentary than that of a recent
corresponding period. So that the time-vista of the past is seen to
answer pretty closely to a visible perspective in which the amount of
apparent error due to foreshortening increases with the distance.

In practice, however, this defect in the imagination of duration leads
to no error. Although, as a concrete image answering to some definite
succession of experiences a year is a gross misrepresentation, as a
general concept implying a collection of a certain number of similar
successions of experience it is sufficiently exact. That is to say,
though we cannot imagine the _absolute_ duration of any such cycle of
experience, we can, by the simple device of conceiving certain durations
as multiples of others, perfectly well compare different periods of
times, and so appreciate their _relative_ magnitudes.

Leaving, then, this constant error in time-appreciation, we will pass to
the variable and more palpable errors in the retrospective measurement
of time. Each person's experience will have told him that in estimating
the distance of a past event by a mere retrospective sense of duration,
he is liable to extraordinary fluctuations of judgment. Sometimes when
the clock strikes we are surprised at the rapidity of the hour. At other
times the timepiece seems rather to have lagged behind its usual pace.
And what is true of a short interval is still more true of longer
intervals, as months and years. The understanding of these fluctuations
will be promoted by our brief glance at the constant errors in
retrospective time-appreciation.

And here it is necessary to distinguish between the sense of duration
which we have during any period, and the retrospective sense which
survives the period, for these do not necessarily agree. The former
rests mainly on our prospective sense of time, whereas the latter must
be altogether retrospective.[121]

Our estimate of time as it passes is commonly said to depend on the
amount of consciousness which we are giving to the fact of its
transition. Thus, when the mind is unoccupied and suffering from
_ennui_, we feel time to move sluggishly. On the other hand, interesting
employment, by diverting the thoughts from time, makes it appear to move
at a more rapid pace. This fact is shown in the common expressions which
we employ, such as "to kill time," and the German _Langweile_.
Similarly, it is said that when we are eagerly anticipating an event, as
the arrival of a friend, the mere fact of dwelling on the interval makes
it appear to swell out.[122]

This view is correct in the main, and is seen, indeed, to follow from
the great psychological principle that what we attend to exists for us
more, has more reality, and so naturally seems greater than what we do
not attend to. At the same time, this principle must be supplemented by
another consideration. Suppose that I am very desirous that time should
not pass quickly. If, for example, I am enjoying myself or indulging in
idleness, and know that I have to be off to keep a not very agreeable
engagement in a quarter of an hour, time will seem to pass too rapidly;
and this not because my thoughts are diverted from the fact of its
transition, for, on the contrary, they are reverting to it more than
they usually do, but because my wish to lengthen the interval leads me
to represent the unwelcome moment as further off than it actually is, in
other words, to construct an ideal representation of the period in
contrast with which the real duration looks miserably short.

Our estimate of duration, when it is over, depends less on this
circumstance of having attended to its transition than on other
considerations. Wundt, indeed, seems to think that the feeling
accompanying the actual flow of time has no effect on the surviving
subjective appreciation; but this must surely be an error, since our
mental image of any period is determined by the character of its
contents. Wundt says that when once a tedious waiting is over, it looks
short because we instantly forget the feeling of tedium. My
self-observation, as well as the interrogation of others, has satisfied
me, on the contrary, that this feeling distinctly colours the
retrospective appreciation. Thus, when waiting at a railway station for
a belated train, I am distinctly aware that each quarter of an hour
looks long, not only as it passes, but when it is over. In fact, I am
disposed to express my feeling as one of disappointment that only so
short an interval has passed since I last looked at my watch.

Nevertheless, I am ready to allow that, though a feeling of tedium, or
the contrary feeling of irritation at the rapidity of time, will linger
for an appreciable interval and colour the retrospective estimate of
time, this backward view is chiefly determined by other considerations.
As Wundt remarks, we have no sense of time's slowness during sleep, yet
on waking we imagine that we have been dreaming for an immensely long
period. This retrospective appreciation is determined by the number and
the degree or intensity of the experiences, and, what comes very much to
the same thing, by the amount of unlikeness, freshness, and
discontinuity characterizing these experiences.

Time, as I have already hinted, is known under the form of a succession
of different conscious experiences. Unbroken uniformity would give us no
sense of time, because it would give us no conscious experience at all.
Strictly speaking, there is no such thing as a perfectly uniform mental
state extending through an appreciable duration. In looking at one and
the same object, even in listening to one and the same tone, I am in no
two successive fractions of a second in exactly the same state of mind.
Slight alterations in the strength of the sensation,[123] in the degree
or direction of attention, and in the composition of that penumbra of
vague images which it calls up, occur at every distinguishable fraction
of time.

This being so, it would seem to follow that the greater the number of
clearly marked changes, and the more impressive and exciting these
transitions, the fuller will be our sense of time. And this is borne out
by individual reflection. When striking and deeply interesting events
follow one another very rapidly, as when we are travelling, duration
appears to swell out.

It is possible that such a succession of stirring experiences may beget
a vague consciousness of time at each successive moment, and apart from
retrospection, simply by force of the change. In other words, without
our distinctly attending to time, a series of novel impressions might,
by giving us the consciousness of change, make us dimly aware of the
numerical richness of our experiences. But, however this be, there is no
doubt that, in glancing back on such a succession of exciting
transitions of mental condition, time appears to expand enormously, just
as it does in looking back on our dream-experience, or that rapid series
of intensified feelings which, according to De Quincey and others, is
produced by certain narcotics.

The reason of this is plain. Such a type of successive experience offers
to the retrospective imagination a large number of distinguishable
points, and since this mode of estimating time depends, as we have seen,
on the extent of the process of filling in, time will necessarily appear
long in this case. On the other hand, when we have been engaged in very
ordinary pursuits, in which few deeply interesting or exciting events
have impressed themselves on memory, our retrospective picture will
necessarily be very much of a blank, and consequently the duration of
the period will seem to be short.

I observed that this retrospective appreciation of time depended on the
degree of connection between the successive experiences. This condition
is very much the same as the other just given, namely, the degree of
uniformity of the experiences, since the more closely the successive
stages of the experience are connected--as when, for example, we are
going through our daily routine of work--the more quiet and unexciting
will be the transition from each stage to its succeeding one. And on the
other hand, all novelty of impression and exciting transition of
experience clearly involves a want of connection. Wundt thinks the
retrospective estimate of a connected series of experiences, such as
those of our daily round of occupations, is defective just because the
effort of attention, which precedes even an imaginative reproduction of
an impression, so quickly accommodates itself in this case to each of
the successive steps, whereas, when the experiences to be recalled are
disconnected, the effort requires more time. In this way, the estimate
of a past duration would be coloured by the sense of time accompanying
the reproductive process itself. This may very likely be the case, yet I
should be disposed to attach most importance to the number of
distinguishable items of experience recalled.

Our representation of the position of a given event in the past is, as I
have tried to show, determined by the movement of imagination in going
back to it from the present. And this is the same thing as to say that
it depends on our retrospective sense of the intervening space. That is
to say, the sense of distance in time, as in space, is the recognition
of a term to a movement. And just as the distance of an object will seem
greater when there are many intervening objects affording points of
measurement, than when there are none (as on the uniform surface of the
sea), so the distance of an event will vary with the number of
recognized intervening points.

The appreciation of the distance of an event in time does not, however,
wholly depend on the character of this movement of imagination. Just as
the apparent distance of a visible object depends _inter alia_ on the
distinctness of the retinal impression, so the apparent temporal
remoteness of a past event depends in part on the degree of intensity
and clearness of the mnemonic image. This is seen even in the case of
those images which we are able distinctly to localize in the
time-perspective. For a series of exciting experiences intervening
between the present and a past event appears not only _directly_ to add
to our sense of distance by constituting an apparently long interval,
but _indirectly_ to add to it by giving an unusual degree of faintness
to the recalled image. An event preceding some unusually stirring series
of experiences gets thrust out of consciousness by the very engrossing
nature of the new experiences, and so tends to grow more faint and
ghost-like than it would otherwise have done.

The full force of this circumstance is best seen in the fact that a very
recent event, bringing with it a deep mental shock and a rapid stirring
of wide tracts of feeling and thought, may get to look old in a
marvellously short space of time. An announcement of the loss of a dear
friend, when sudden and deeply agitating, will seem remote even after an
hour of such intense emotional experience. And the same twofold
consideration probably explains the well-known fact that a year seems
much shorter to the adult than to the child. The novel and comparatively
exciting impressions of childhood tend to fill out time in retrospect,
and also to throw back remote events into a dimly discernible region.

Now, this same circumstance, the degree of vividness or of faintness of
the mnemonic image, is that which determines our idea of distance when
the character of the intervening experiences produces no appreciable
effect.[124] This is most strikingly illustrated in those imperfect
kinds of recollection in which we are unable to definitely localize the
mnemonic image. To the consideration of these we will now turn.

B. _Indefinite Localization._

Speaking roughly and generally, we may say that the vividness of an
image of memory decreases in proportion as the distance of the event
increases. And this is the rule which we unconsciously apply in
determining distance in time. Nevertheless, this rule gives us by no
means an infallible criterion of distance. The very fact that different
people so often dispute about the dates and the order of past events
experienced in common, shows pretty plainly that images of the same age
tend to arise in the mind with very unequal degrees of vividness.

Sometimes pictures of very remote incidents may suddenly present
themselves to our minds with a singular degree of brightness and force.
And when this is the case, there is a disposition to think of them as
near. If the relations of the event to other events preceding and
succeeding it are not remembered, this momentary illusion will persist.
We have all heard persons exclaim, "It seems only yesterday," under the
sense of nearness which accompanies a recollection of a remote event
when vividly excited. The most familiar instance of such lively
reproduction is the feeling which we experience on revisiting the scene
of some memorable event. At such a time the past may return with
something of the insistence of a present perceived reality. In passing
from place to place, in talking with others, and in reading, we are
liable to the sudden return by hidden paths of association of images of
incidents that had long seemed forgotten, and when they thus start up
fresh and vigorous, away from their proper surroundings, they invariably
induce a feeling of the propinquity of the events.

In many cases we cannot say why these particular images, long buried in
oblivion, should thus suddenly regain so much vitality. There seems,
indeed, to be almost as much that is arbitrary and capricious in the
selection by memory of its vivid images as in the selection of its
images as a whole; and, this being so, it is plain that we are greatly
exposed to the risk of illusion from this source.

There is an opposite effect in the case of recent occurrences that, for
some reason or another, have left but a faint impression on the memory;
though this fact is not, perhaps, so familiar as the other. I met a
friend, we will suppose, a few days since at my club, and we exchanged a
few words. My mind was somewhat preoccupied at the time, and the
occurrence did not stamp itself on my recollection. To-day I meet him
again, and he reminds me of a promise I made him at the time. His
reminder suffices to restore a dim image of the incident, but the fact
of its dimness leads to the illusion that it really happened much longer
ago, and it is only on my friend's strong assurances, and on reasoning
from other data that it must have occurred the day he mentions, that I
am able to dismiss the illusion.

The most striking examples of the illusory effect of mere vividness,
involving a complete detachment of the event from the prominent
landmarks of the past, are afforded by public events which lie outside
the narrower circle of our personal life, and which do not in the
natural course of things become linked to any definitely localized
points in the field of memory. These events may be very stirring and
engrossing for the time, but in many cases they pass out of the mind
just as suddenly as they entered it. We have no occasion to revert to
them, and if by chance we are afterwards reminded of them, they are
pretty certain to look too near, just because the fact of their having
greatly interested us has served to render their images particularly

A curious instance of this illusory effect was supplied not long since
by the case of the ex-detectives, the expiration of whose term of
punishment (three years) served as an occasion for the newspapers to
recall the event of their trial and conviction. The news that three
years had elapsed since this well-remembered occurrence proved very
startling to myself, and to a number of my friends, all of us agreeing
that the event did not seem to be at more than a third of its real
distance. More than one newspaper commented on the apparent rapidity of
the time, and this shows pretty plainly that there was some cause at
work, such as I have suggested, producing a common illusion.

I have treated of these illusions connected with the estimate of past
time and the dating of past events as passive illusions, not involving
any active predisposition on the part of the imagination. At the same
time, it is possible that error in these matters may occasionally depend
on a present condition of the feelings and the imagination. It seems
plain that since the apparent degree of remoteness of an event not
distinctly localized in the past varies inversely as the degree of
vividness of the mnemonic image, any conscious concentration of mind on
a recollection will tend to bring it too near. In this way, then, an
illusory propinquity may be given to a recalled event through a mere
desire to dwell on it, or even a capricious wish to deceive one's self.

When, for example, old friends come together and talk over the days of
yore, there is a gradual reinstatement of seemingly lost experiences,
which often partakes of the character of a semi-voluntary process of
self-delusion. Through the cumulative effect of mutual reminder,
incident after incident returns, adding something to the whole picture
till it acquires a degree of completeness, coherence, and vividness that
render it hardly distinguishable from a very recent experience. The
process is like looking at a distant object through a field-glass.
Mistiness disappears, fresh details come into view, till we seem to
ourselves to be almost within reach of the object.

Where the mind habitually goes back to some painful circumstance under
the impulse of a morbid disposition to nurse regret, this momentary
illusion may become recurring, and amount to a partial confusion of the
near and the remote in our experience. An injury long brooded on seems
at length a thing that continually moves forward as we move; it always
presents itself to our memories as a very recent event. In states of
insanity brought on by some great shock, we see this morbid tendency to
resuscitate the dead past fully developed, and remote events and
circumstances becoming confused with present ones.

On the other hand, in more healthy states of mind there presents itself
an exactly opposite tendency, namely, an impulse of the will to banish
whatever when recalled gives pain to the furthest conceivable regions of
the past. Thus, when we have lost something we cherished dearly, and the
recollection of it brings fruitless longing, we instinctively seek to
expel the recollection from our minds. The very feeling that what has
been can never again be, seems to induce this idea of a vast remoteness
of the vanished reality. When, moreover, the lost object was fitted to
call forth the emotion of reverence, the impulse to magnify the
remoteness of the loss may not improbably be reinforced by the
circumstance that everything belonging to the distant past is fitted on
that account to excite a feeling akin to reverence. So, again, any
rupture in our mental development may lead us to exaggerate the distance
of some past portion of our experience. When we have broken with our
former selves, either in the way of worsening or bettering, we tend to
project these further into the past.

It is only when the sting of the recollection is removed, when, for
example, the calling up of the image of a lost friend is no longer
accompanied with the bitterness of futile longing, that a healthy mind
ventures to nourish recollections of such remote events and to view
these as part of its recent experiences. In this case the mnemonic image
becomes transformed into a kind of present emotional possession, an
element of that idealized and sublimated portion of our experience with
which all imaginative persons fill up the emptiness of their actual
lives, and to which the poet is wont to give an objective embodiment in
his verse.

_Distortions of Memory._

It is now time to pass to the second group of illusions of memory,
which, according to the analogy of visual errors, may be called
atmospheric illusions. Here the degree of error is greater than in the
case of illusions of time-perspective, since the very nature of the
events or circumstances is misconceived. We do not recall the event as
it happened, but see it in part only, and obscured, or bent and
distorted as by a process of refraction. Indeed, this transformation of
the past does closely correspond with the transformation of a visible
object effected by intervening media. Our minds are such refracting
media, and the past reappears to us not as it actually was when it was
close to us, but in numerous ways altered and disguised by the
intervening spaces of our conscious experience.

To begin with, what we call recollection is uniformly a process of
softening the reality. When we appear to ourselves to realize events of
the remote past, it is plain that our representation in a general way
falls below the reality: the vividness, the intensity of our impressions
disappears. More particularly, so far as our experiences are emotional,
they tend thus to become toned down by the mere lapse of time and the
imperfections of our reproductive power. That which we seem to see in
the act of recollection is thus very different from the reality.

Not only is there this general deficiency in mnemonic representation,
there are special deficiencies due to the fact of oblivescence. Our
memories restore us only fragments of our past life. And just as objects
seen imperfectly at a great distance may assume a shape quite unlike
their real one, so an inadequate representation of a past event by
memory often amounts to misrepresentation. When revisiting a place that
we have not seen for many years, we are apt to find that our
recollection of it consisted only of some insignificant details, which
arranged themselves in our minds into something oddly unlike the actual
scene. So, too, some accidental accompaniment of an incident in early
life is preserved, as though it were the main feature, serving to give
quite a false colouring to the whole occurrence.

It seems quite impossible to account for these particular survivals,
they appear to be so capricious. When a little time has elapsed after an
event, and the attendant circumstances fade away from memory, it is
often difficult to say why we were impressed with it as we afterwards
prove to have been. It is no doubt possible to see that many of the
recollections of our childhood owe their vividness to the fact of the
exceptional character of the events; but this cannot always be
recognized. Some of them seem to our mature minds very oddly selected,
although no doubt there are in every case good reasons, if we could only
discover them, why those particular incidents rather than any others
should have been retained.

The liability to error resulting from mere oblivescence and the
arbitrary selection of mental images is seen most plainly, perhaps, in
our subsequent representation and estimate of whole periods of early
life. Our idea of any stage of our past history, as early childhood, or
school days, is built up out of a few fragmentary intellectual relics
which cannot be certainly known to answer to the most important and
predominant experiences of the time. When, for example, we try to decide
whether our school days were our happiest days, as is so often alleged,
it is obvious that we are liable to fall into illusion through the
inadequacy of memory to preserve characteristic or typical features, and
none but these. We cannot easily recall the ordinary every-day level of
feeling of a distant period of life, but rather think of exceptional
moments of rejoicing or depression. The ordinary man's idea of the
emotional experience of his school days is probably built up out of a
few scrappy recollections of extraordinary and exciting events, such as
unexpected holidays, success in the winning of prizes, famous "rows"
with the masters, and so on.

Besides the impossibility of getting at the average and prevailing
mental tone of a distant section of life, there is a special difficulty
in determining the degree of happiness of the past, arising from the
fact that our memory for pleasures and for pains may not be equally
good. Most people, perhaps, can recall the enjoyments of the past much
more vividly than the sufferings. On the other hand, there seem to be
some who find the retention of the latter the easier of the two. This
fact should not be forgotten in reading the narrative of early hardships
which some recent autobiographies have given us.

Not only does our idea of the past become inexact by the mere decay and
disappearance of essential features, it becomes positively incorrect
through the gradual incorporation of elements that do not properly
belong to it. Sometimes it is easy to see how these extraneous ideas get
imported into our mental representation of a past event. Suppose, for
example, that a man has lost a valuable scarf-pin. His wife suggests
that a particular servant, whose reputation does not stand too high, has
stolen it. When he afterwards recalls the loss, the chances are that he
will confuse the fact with the conjecture attached to it, and say he
remembers that this particular servant did steal the pin. Thus, the past
activity of imagination serves to corrupt and partially falsify
recollections that have a genuine basis of fact.

It is evident that this class of mnemonic illusions approximates in
character to illusions of perception. When the imagination supplies the
interpretation at the very time, and the mind reads this into the
perceived object, the error is one of perception. When the addition is
made afterwards, on reflecting upon the perception, the error is one of
memory. The "fallacies of testimony" which depend on an adulteration of
pure observation with inference and conjecture, as, for example, the
inaccurate and wild statements of people respecting their experiences at
spiritualist _séances_, while they illustrate the curious blending of
both kinds of error, are probably much oftener illusions of memory than
of perception.[125]

Although in many cases we can account to ourselves for this confusion of
fact and imagination, in other cases it is difficult to see any close
relation between the fact remembered and the foreign element imported
into it. An idea of memory seems sometimes to lose its proper moorings,
so to speak; to drift about helplessly among other ideas, and finally,
by some chance, to hook itself on to one of these, as though it
naturally belonged to it. Anybody who has had an opportunity of
carefully testing the truthfulness of his recollection of some remote
event in early life will have found how oddly extraneous elements become
incorporated into the memorial picture. Incidents get put into wrong
places, the wrong persons are introduced into a scene, and so on. Here
again we may illustrate the mnemonic illusion by a visual one. When a
tree standing before or behind a house and projecting above or to the
side of it is not sharply distinguished from the latter, it may serve to
give it a very odd appearance.

These confusions of the mental image may arise even when only a short
interval has elapsed. In the case of many of the fleeting impressions
that are only half recollected, this kind of error is very easy. Thus,
for example, I may have lent a book to a friend last week. I really
remember the act of lending it, but have forgotten the person. But I am
not aware of this. The picture of memory has unknowingly to myself been
filled up by this unconscious process of shifting and rearrangement, and
the idea of another person has by some odd accident got substituted for
that of the real borrower. If we could go deeply enough into the matter,
we should, of course, be able to explain why this particular confusion
arose. We might find, for example, that the two persons were associated
in my mind by a link of resemblance, or that I had dealings with the
other person about the same time. Similarly, when we manage to join an
event to a wrong place, we may find that it is because we heard of the
occurrence when staying at the particular locality, or in some other way
had the image of the place closely associated in our minds with the
event. But often we are wholly unable to explain the displacement.

So far I have been speaking of the passive processes by which the past
comes to wear a new face to our imaginations. In these our present
habits of feeling and thinking take no part; all is the work of the
past, of the decay of memory, and the gradual confusion of images. This
process of disorganization may be likened to the action of damp on some
old manuscript, obliterating some parts, altering the appearance of
others, and even dislocating certain portions. Besides this passive
process of transformation, there is a more active one in which our
present minds co-operate. In memory, as in perception and introspection,
there is a process of preparation or preadjustment of mind, and here
will be found room for what I had called active error. This may be
illustrated by the operation of "interpreting" an old manuscript which
has got partially obliterated, or of "restoring" a faded picture; in
each of which operations error will be pretty sure to creep in through
an importation of the restorer's own ideas into the relic of the past.

Just as when distant objects are seen mistily our imaginations come into
play, leading us to fancy that we see something completely and
distinctly, so when the images of memory become dim, our present
imagination helps to restore them, putting a new patch into the old
garment. If only there is some relic of the past event preserved, a bare
suggestion of the way in which it may have happened will often suffice
to produce the conviction that it actually did happen in this way. The
suggestions that naturally arise in our minds at such times will bear
the stamp of our present modes of experience and habits of thought.
Hence, in trying to reconstruct the remote past, we are constantly in
danger of importing our present selves into our past selves.

The kind of illusion of memory which thus depends on the spontaneous or
independent activity of present imagination is strikingly illustrated in
the curious cases of mistaken identity with which the proceedings of
our law courts supply us from time to time. When a witness in good
faith, but erroneously, affirms that a man is the same as an old
acquaintance of his, we may feel sure that there is some striking point
or points of similarity between the two persons. But this of itself
would only partly account for the illusion, since we often see new faces
that, by a number of curious points of affinity, call up in a
tantalizing way old and familiar ones. What helps in this case to
produce the illusion is the preconception that the present man is the
witness's old friend. That is to say, his recollection is partly true,
though largely false. He does really recall the similar feature,
movement, or tone of voice; he only seems to himself to recall the rest
of his friend's appearance; for, to speak correctly, he projects the
present impression into the past, and constructs his friend's face out
of elements supplied by the new one. Owing to this cause, an illusion of
memory is apt to multiply itself, one man's assertion of what happened
producing by contagion a counterfeit of memory's record in other minds.

I said just now that we tend to project our present modes of experience
into the past. We paint our past in the hues of the present. Thus we
imagine that things which impressed us in some remote period of life
must answer to what is impressive in our present stage of mental
development. For example, a person recalls a hill near the home of his
childhood, and has the conviction that it was of great height. On
revisiting the place he finds that the eminence is quite insignificant.
How can we account for this? For one thing, it is to be observed that to
his undeveloped childish muscles the climbing to the top meant a
considerable expenditure of energy, to be followed by a sense of
fatigue. The man remembers these feelings, and "unconsciously reasoning"
by present experience, that is to say, by the amount of walking which
would now produce this sense of fatigue, imagines that the height was
vastly greater than it really was. Another reason is, of course, that a
wider knowledge of mountains has resulted in a great alteration of the
man's standard of height.

From this cause arises a tendency generally to exaggerate the
impressions of early life. Youth is the period of novel effects, when
all the world is fresh, and new and striking impressions crowd in
thickly on the mind. Consequently, it takes much less to produce a given
amount of mental excitation in childhood than in after-life. In looking
back on this part of our history, we recall for the most part just those
events and scenes which deeply stirred our minds by their strangeness,
novelty, etc., and so impressed themselves on the tablet of our memory;
and it is this sense of something out of the ordinary beat that gives
the characteristic colour to our recollection. In other words, we
remember something as wonderful, admirable, exceptionally delightful,
and so on, rather than as a definitely imagined event. This being so, we
unconsciously transform the past occurrence by reasoning from our
present standard of what is impressive. Who has not felt an unpleasant
disenchantment on revisiting some church, house, or park that seemed a
wondrous paradise to his young eyes? All our feelings are capable of
leading us into this kind of illusion. What seemed beautiful or awful
to us as children, is now pictured in imagination as corresponding to
what moves our mature minds to delight or awe. One cannot help wondering
what we should think of our early heroes or heroines if we could see
them again with our adult eyes exactly as they were.

While the past may thus take on an illusory hue through the very
progress of our experience and our emotional life, it may become further
transformed by a more conscious process, namely, the idealizing touch of
a present feeling. The way in which the emotions of love, reverence, and
so on, thus transform their lost objects is too well known to need
illustration. Speaking generally, we may say that in healthy minds the
play of these impulses of feeling results in a softening of the harsher
features of the past, and in an idealization of its happier and brighter
aspects. As Wordsworth says, we may assign to Memory a pencil--

  "That, softening objects, sometimes even
     Outstrips the heart's demand;

  "That smoothes foregone distress, the lines
     Of lingering care subdues,
   Long-vanished happiness refines,
     And clothes in brighter hues."[126]

Enough has now been said, perhaps, to show in how many ways our
retrospective imagination transforms the actual events of our past life.
So thoroughly, indeed, do the relics of this past get shaken together in
new kaleidoscopic combinations, so much of the result of later
experiences gets imported into our early years, that it may well be
asked whether, if the record of our actual life were ever read out to
us, we should be able to recognize it. It looks as though we could be
sure of recalling only recent events with any degree of accuracy and
completeness. As soon as they recede at any considerable distance from
us, they are subject to a sort of atmospheric effect. Much grows
indistinct and drops altogether out of sight, and what is still seen
often takes a new and grotesquely unlike shape. More than this, the play
of fancy, like the action of some refracting medium, bends and distorts
the outlines of memory's objects, making them wholly unlike the

_Hallucinations of Memory._

We will now go on to the third class of mnemonic error, which I have
called the spectra of memory, where there is not simply a transformation
of the past event, but a complete imaginative creation of it. This class
of error corresponds, as I have observed, to an hallucination in the
region of sense-perception. And just as we distinguished between those
hallucinations of sense which arise first of all through some
peripherally caused subjective sensation, and those which want even this
element of reality and depend altogether on the activity of imagination,
so we may mark off two classes of mnemonic hallucination. The false
recollection may correspond to something past--and to this extent be a
recollection--though not to any objective fact, but only to a subjective
representation of such a fact, as, for example, a dream. In this case
the imitation of the mnemonic process may be very definite and complete.
Or the false recollection may be wholly a retrojection of a present
mental image, and so by no stretch of language be deserving of the name

It is doubtful whether by any effort of will a person could bring
himself to regard a figment of his present imagination as representative
of a past reality. Definite and complete hallucinations of this sort do
not in normal circumstances arise. It seems necessary for a complete
illusion of memory that there should be something past and recovered at
the moment, though this may not be a real personal experience.[127] On
the other hand, it is possible, as we shall presently see, under certain
circumstances, to create out of present materials, and in a vague and
indefinite shape, pure phantoms of past experience, that is to say,
quasi-mnemonic images to which there correspond no past occurrences

All recollection, as we have seen, takes place by means of a present
mental image which returns with a certain degree of vividness, and is
instantaneously identified with some past event. In many cases this
instinctive process of identification proves to be legitimate, for, as a
matter of fact, real impressions are the first and the commonest source
of such lively mnemonic images. But it is not always so. There are other
sources of our mental imagery which compete, so to speak, with the
region of real personal experience. And sometimes these leave behind
them a vivid image having all the appearance of a genuine mnemonic
image. When this is so, it is impossible by a mere introspective glance
to detect the falsity of the message from the past. We are in the same
position as the purchaser in a jet market, where a spurious commodity
has got inextricably mixed up with the genuine, and there is no ready
criterion by which he can distinguish the true from the false. Such a
person, if he purchases freely, is pretty sure to make a number of
mistakes. Similarly, all of us are liable to take counterfeit mnemonic
images for genuine ones; that is to say, to fall into an illusion of
"recollecting" what never really took place.

But what, it may be asked, are these false and illegitimate sources of
mnemonic images, these unauthorized mints which issue a spurious mental
coinage, and so confuse the genuine currency? They consist of two
regions of our internal mental life, which most closely resemble the
actual perception of real things in vividness and force, namely,
dream-consciousness and waking imagination. Each of these may introduce
into the mind vivid images which afterwards tend, under certain
circumstances, to assume the guise of recollections of actual events.

That our dream-experience may now and again lead us into illusory
recollection has already been hinted. And it is easy to understand why
this is so. When dreaming we have, as we have seen, a mental experience
which closely approximates in intensity and reality to that of waking
perception. Consequently, dreams may leave behind them, for a time,
vivid images which simulate the appearance of real images of memory.
Most of us, perhaps, have felt this after-effect of dreaming on our
waking thoughts. It is sometimes very hard to shake off the impression
left by a vivid dream, as, for example, that a dead friend has returned
to life. During the day that follows the dream, we have at intermittent
moments something like an assurance that we have seen our lost friend;
and though we immediately correct the impression by reflecting that we
are recalling but a dream, it tends to revive within us with a strange

In addition to this proximate effect of a dream in disturbing the normal
process of recollection, there is reason to suppose that dreams may
exert a more remote effect on our memories. So widely different in its
form is our dreaming from our waking experience, that our dreams are
rarely recalled as wholes with perfect distinctness. They revive in us
only as disjointed fragments, and only for brief moments when some
accidental resemblance in the present happens to stir the latent trace
they have left on our minds. We get sudden flashes out of our
dream-world, and the process is too rapid, too incomplete for us to
identify the region whence the flashes come.

It is highly probable that our dreams are, to a large extent, answerable
for the sense of familiarity that we sometimes experience in visiting a
new locality or in seeing a new face. If, as we have found some of the
best authorities saying, we are, when asleep, always dreaming more or
less distinctly, and if, as we know, dreaming is a continual process of
transformation of our waking impressions in new combinations, it is not
surprising that our dreams should sometimes take the form of forecasts
of our waking life, and that consequently objects and scenes of this
life never before seen should now and again wear a familiar look.

That some instances of this puzzling sense of familiarity can be
explained in this way is proved. Thus, Paul Radestock, in the work
_Schlaf und Traum_, already quoted, tells us: "When I have been taking a
walk, with my thoughts quite unfettered, the idea has often occurred to
me that I had seen, heard, or thought of this or that thing once before,
without being able to recall when, where, and in what circumstances.
This happened at the time when, with a view to the publication of the
present work, I was in the habit of keeping an exact record of my
dreams. Consequently, I was able to turn to this after these
impressions, and on doing so I generally found the conjecture confirmed
that I had previously dreamt something like it." Scientific inquiry is
often said to destroy all beautiful thoughts about nature and life; but
while it destroys it creates. Is it not almost a romantic idea that just
as our waking life images itself in our dreams, so our dream-life may
send back some of its shadowy phantoms into our prosaic every-day world,
touching this with something of its own weird beauty?

Not only may dreams beget these momentary illusions of memory, they may
give rise to something like permanent illusions. If a dream serves to
connect a certain idea with a place or person, and subsequent experience
does not tend to correct this, we may keep the belief that we have
actually witnessed the event. And we may naturally expect that this
result will occur most frequently in the case of those who habitually
dream vividly, as young children.

It seems to me that many of the quaint fancies which children get into
their heads about things they hear of arise in this way. I know a person
who, when a child, got the notion that when his baby-brother was weaned,
he was taken up on a grassy hill and tossed about. He had a vivid idea
of having seen this curious ceremony. He has in vain tried to get an
explanation of this picturesque rendering of an incident of babyhood
from his friends, and has come to the conclusion that it was the result
of a dream. If, as seems probable, children's dreams thus give rise to
subsequent illusions of memory, the fact would throw a curious light on
some of the startling quasi-records of childish experience to be met
with in autobiographical literature.

Odd though it may at first appear, old age is said to resemble youth in
this confusion of dream-recollection with the memory of waking
experience. Dr. Carpenter[128] tells us of "a lady of advanced age
who ... continually dreams about passing events, and seems entirely unable
to distinguish between her dreaming and her waking experiences,
narrating the former with implicit belief in them, and giving directions
based on them." This confusion in the case of the old may possibly
arise not from an increase in the intensity of the dreams, but from a
decrease in the intensity of the waking impressions. As Sir Henry
Holland remarks,[129] in old age life approaches to the state of a

The other source of what may, by analogy with the hallucinations of
sense, be called the peripherally originating spectra of memory is
waking imagination. In certain morbid conditions of mind, and in the
case of the few healthy minds endowed with special imaginative force,
the products of this mental activity, may, as we saw when dealing with
illusions of perception, closely resemble dreams in their vividness and
apparent actuality. When this is the case, illusions of memory may arise
at once just as in the case of dreams. This will happen more easily when
the imagination has for some time been occupied with the same group of
ideal scenes, persons, or events. To Dickens, as is well known, his
fictitious characters were for the time realities, and after he had
finished his story their forms and their doings lingered with him,
assuming the aspect of personal recollections. So, too, the energetic
activity of imagination which accompanies a deep and absorbing sympathy
with another's painful experiences, may easily result in so vivid a
realization of all their details as to leave an after-sense of
_personal_ suffering. All highly sympathetic persons who have closely
accompanied beloved friends through a great sorrow have known something
of this subsequent feeling.

The close connection and continuity between normal and abnormal states
of mind is illustrated in the fact that in insanity the illusion of
taking past imaginations for past realities becomes far more powerful
and persistent. Abercrombie (_Intellectual Powers_, Part III. sec. iv. §
2, "Insanity") speaks of "visions of the imagination which have formerly
been indulged in of that kind which we call waking dreams or
castle-building recurring to the mind in this condition, and now
believed to have a real existence." Thus, for example, one patient
believed in the reality of the good luck previously predicted by a
fortune-teller. Other writers on mental disease observe that it is a
common thing for the monomaniac to cherish the delusion that he has
actually gained the object of some previous ambition, or is undergoing
some previously dreaded calamity.

Nor is it necessary to these illusions of memory that there should be
any exceptional force of imagination. A fairly vivid representation to
ourselves of anything, whether real or fictitious, communicated by
others, will often result in something very like a personal
recollection. In the case of works of history and fiction, which adopt
the narrative tense, this tendency to a subsequent illusion of memory is
strengthened by the disposition of the mind at the moment of reading to
project itself backwards as in an act of recollection. This is a point
which will be further dealt with in the next chapter.

In most cases, however, illusions of memory growing out of previous
activities of the imagination appear only after the lapse of some time,
when in the natural course of things the mental images derived from
actual experience would sink to a certain degree of faintness. Habitual
novel-readers often catch themselves mistaking the echo of some passage
in a good story for the trace left by an actual event. A person's name,
a striking saying, and even an event itself, when we first come across
it or experience it, may for a moment seem familiar to us, and to recall
some past like impression, if it only happens to resemble something in
the works of a favourite novelist. And so, too, any recital of another's
experience, whether oral or literary, if it deeply interests us and
awakens a specially vivid imagination of the events described, may
easily become the starting-point of an illusory recollection.

Children are in the habit of "drinking in" with their vigorous and eager
imaginations what is told them and read to them, and hence they are
specially likely to fall into this kind of error. Not only so: when they
grow up and their early recollections lose their definiteness, becoming
a few fragments saved from a lost past, it must pretty certainly happen
that if any ideas derived from these recitals are preserved, they will
simulate the form of memories. Thus, I have often caught myself for a
moment under the sway of the illusion that I actually visited the
Exhibition of 1851, the reason being that I am able to recall the
descriptions given to me of it by my friends, and the excitement
attending their journey to London on the occasion. It is to be added
that repetition of the act of imagination will tend still further to
deepen the subsequent feeling that we are recollecting something. As
Hartley well observes, a man, by repeating a story, easily comes to
suppose that he remembers it.[130]

Here, then, we have another source of error that we must take into
account in judging of the authenticity of an autobiographical narration
of the events of childhood. The more imaginative the writer, the greater
the risk of illusion from this source as well as from that of
dream-fancies. It is highly probable, indeed, that in such full and
explicit records of very early life as those given by Rousseau, by
Goethe, or by De Quincey, some part of the quasi-narrative is based on
mental images which come floating down the stream of time, not from the
substantial world of the writer's personal experience, but from the airy
region of dream-land or of waking fancy.

It is to be added that even when the quasi-recollection does answer to a
real event of childish history, it may still be an illusion. The fact
that others, in narrating events to us, are able to awaken imaginations
that afterwards appear as past realities, suggests that much of our
supposed early recollection owes its existence to what our parents and
friends have from time to time told us respecting the first stages of
our history.[131] We see, then, how much uncertainty attaches to all
autobiographical description of very early life.

Modern science suggests another possible source of these distinct
spectra of memory. May it not happen that, by the law of hereditary
transmission, which is now being applied to mental as well as bodily
phenomena, ancestral experiences will now and then reflect themselves
in our mental life, and so give rise to apparently personal
recollections? No one can say that this is not so. When the infant first
steadies his eyes on a human face, it may, for aught we know, experience
a feeling akin to that described above, when through a survival of
dream-fancy we take some new scene to be already familiar. At the age
when new emotions rapidly develop themselves, when our hearts are full
of wild romantic aspirations, do there not seem to blend with the eager
passion of the time deep resonances of a vast and mysterious past, and
may not this feeling be a sort of reminiscence of prenatal, that is,
ancestral experience?

This idea is certainly a fascinating one, worthy to be a new scientific
support for the beautiful thought of Plato and of Wordsworth. But in our
present state of knowledge, any reasoning on this supposition would
probably appear too fanciful. Some day we may find out how much
ancestral experience is capable of bequeathing in this way, whether
simply shadowy, undefinable mental tendencies, or something like
definite concrete ideas. If, for example, it were found that a child
that was descended from a line of seafaring ancestors, and that had
never itself seen or heard of the "dark-gleaming sea," manifested a
feeling of recognition when first beholding it, we might be pretty sure
that such a thing as recollection of prenatal events does take place.
But till we have such facts, it seems better to refer the "shadowy
recollections" to sources which fall within the individual's own

We may now pass to those hallucinations of memory which are analogous to
the _centrally_ excited hallucinations of sense-perception. As I have
observed, these are necessarily vague and imperfectly developed.

I have already had occasion to touch on the fact of the vast amount of
our forgotten experience. And I observed that forgetfulness was a common
negative condition of mnemonic illusion. I have now to complete this
statement by the observation that total forgetfulness of any period or
stage of our past experience necessarily tends to a vague kind of
hallucination. In looking back on the past, we see no absolute gaps in
the continuity of our conscious life; our image of this past is
essentially one of an unbroken series of conscious experiences. But if
through forgetfulness a part of the series is effaced from memory, how,
it may be asked, is it possible to construct this perfectly continuous
line? The answer is that we fill up such lacunæ vaguely by help of some
very imperfectly imagined common type of conscious experience. Just as
the eye sees no gap in its field of vision corresponding to the "blind
spot" of the retina, but carries its impression over this area, so
memory sees no lacuna in the past, but carries its image of conscious
life over each of the forgotten spaces.

Sometimes this process of filling in gaps in the past becomes more
complete. Thus, for example, in recalling a particular night a week or
so ago, I instinctively represent it to myself as so many hours of lying
in bed with the waking sensations appropriate to the circumstances, as
those of bodily warmth and rest, and of the surrounding silence and

It is apparent that I cannot conceive myself apart from some mode of
conscious experience. In thinking of myself in any part of the past or
future in which there is actually no consciousness, or of which the
conscious content is quite unknown to me, I necessarily imagine myself
as consciously experiencing something. If I picture myself under any
definitely conceived circumstances, I irresistibly import into my mental
image the feelings appropriate to these surroundings. In this way,
people tend to imagine themselves after death as lying in the grave,
feeling its darkness and its chilliness. If the circumstances of the
time are not distinctly represented, the conception of the conscious
experience which constitutes that piece of the ego is necessarily vague,
and seems generally to resolve itself into a representation of ourselves
as dimly _self-conscious_. What this consciousness of self consists of
is a point that will be taken up presently.

_Illusions with respect to Personal Identity._

It would seem to follow from these errors in imaginatively filling up
our past life, that our consciousness of personal identity is by no
means the simple and exact process which it is commonly supposed to be.
I have already remarked that the very fact of there being so large a
region of the irrevocable in our past experience proves our
consciousness of personal continuity to be largely a matter of
inference, or of imaginative conjecture, and not simply of immediate
recollection. Indeed, it may be said that our power of ignoring whole
regions of the past and of leaping complacently over huge gaps in our
memory and linking on conscious experience with conscious experience,
involves an illusory sense of continuity, and so far of personal
identity. Thus, our ordinary image of our past life, if only by omitting
the very large fraction passed in sleep, in at least an approximately
unconscious state, clearly contains an ingredient of illusion.[132]

It is to be added that the numerous falsifications of our past history,
which our retrospective imagination is capable of perpetrating, make our
representation of ourselves at different moments and in different stages
of our past history to a considerable extent illusory. Thus, though to
mistake a past dream-experience for a waking one may not be to lose or
confuse the sense of identity, since our dreams are, after all, a part
of our experience, yet to imagine that we have ourselves seen what we
have only heard from another or read is clearly to confuse the
boundaries of our identity. And with respect to longer sections of our
history, it is plain that when we wrongly assimilate our remote to our
present self, and clothe our childish nature with the feelings and the
ideas of our adult life, we identify ourselves overmuch. In this way,
through the corruption of our memory, a kind of sham self gets mixed up
with the real self, so that we cannot, strictly speaking, be sure that
when we project a mnemonic image into the remote past we are not really
running away from our true personality.

So far I have been touching only on slight errors in the recognition of
that identical self which is represented as persisting through all the
fluctuations of conscious life. Other and grosser illusions connected
with personal identity are also found to be closely related to defects
or disturbances of the ordinary mnemonic process, and so can be best
treated here. In order to understand these, we must inquire a little
into the nature of our idea and consciousness of a persistent self.
Here, again, I would remind the reader that I am treating the point only
so far as it can be treated scientifically or empirically, that is to
say, by examining what concrete facts or data of experience are taken up
into the idea of self. I do not wish to foreclose the philosophic
question whether anything more than this empirical content is involved
in the conception.

My idea of myself as persisting appears to be built up of certain
similarities in the succession of my experiences. Thus, my permanent
self consists, on the bodily side, of a continually renewable perception
of my own organism, which perception is mainly visual and tactual, and
which remains pretty constant within certain limits of time. With this
objective similarity is closely conjoined a subjective similarity. Thus,
the same sensibilities continue to characterize the various parts of my
organism. Similarly, there are the higher intellectual, emotional, and
moral peculiarities and dispositions. My idea of my persistent self is
essentially a collective image representing a relatively unchanging
material object, endowed with unchanging sensibilities and forming a
kind of support for permanent higher mental attributes.

The construction of this idea of an enduring unchanging ego is rendered
very much easier by the fact that certain concrete feelings are
approximately constant elements in our mental life. Among these must be
ranked first that dimly discriminated mass of organic sensation which in
average states of health is fairly constant, and which stands in sharp
contrast to the fluctuating external sensations. These feelings enter
into and profoundly colour each person's mental image of himself. In
addition to this, there are the frequently recurring higher feelings,
the dominant passions and ideas which approximate more or less closely
to constant factors of our conscious experience.

This total image of the ego becomes defined and rendered precise by a
number of distinctions, as that between my own body or that particular
material object with which are intimately united all my feelings, and
other material objects in general; then between my organism and other
human organisms, with which I learn to connect certain feelings
answering to my own, but only faintly represented instead of actually
realized feelings. To these prime distinctions are added others, hardly
less fundamental, as those between my individual bodily appearance and
that of other living bodies, between my personal and characteristic
modes of feeling and thinking and those of others, and so on.

Our sense of personal identity may be said to be rooted in that special
side of the mnemonic process which consists in the linking of all
sequent events together by means of a thread of common consciousness. It
is closely connected with that smooth, gliding movement of imagination
which appears to involve some more or less distinct consciousness of the
uniting thread of similarity. And so long as this movement is possible,
so long, that is to say, as retrospective imagination detects the common
element, which we may specifically call the recurring consciousness of
self, so long is there the undisturbed assurance of personal identity.
Nay, more, even when such a recognition might seem to be difficult, if
not impossible, as in linking together the very unlike selves, viewed
both on their objective and subjective sides, of childhood, youth, and
mature life, the mind manages, as we have seen, to feign to itself a
sufficient amount of such similarity.

But this process of linking stage to stage, of discerning the common or
the recurring amid the changing and the evanescent, has its limits.
Every great and sudden change in our experience tends, momentarily at
least, to hinder the smooth reflux of imagination. It makes too sharp a
break in our conscious life, so that imagination is incapable of
spanning the gap and realizing the then and the now as parts of a
connected continuous tissue.[133]

These changes may be either objective or subjective. Any sudden
alteration of our bodily appearance sensibly impedes the movement of
imagination. A patient after a fever, when he first looks in the glass,
exclaims, "I don't know myself." More commonly the bodily changes which
affect the consciousness of an enduring self are such as involve
considerable alterations of coenæsthesis, or the mass of stable
organic sensation. Thus, the loss of a limb, by cutting off a portion of
the old sensations through which the organism may be said to be
immediately felt, and by introducing new and unfamiliar feelings, will
distinctly give a shock to our consciousness of self.

Purely subjective changes, too, or, to speak correctly, such as are
known subjectively only, will suffice to disturb the sense of personal
unity. Any great moral shock, involving something like a revolution in
our recurring emotional experience, seems at the moment to rupture the
bond of identity. And even some time after, as I have already remarked,
such cataclysms in our mental geology lead to the imaginative thrusting
of the old personality away from the new one under the form of a "dead

We see, then, that the failure of our ordinary assurance of personal
identity is due to the recognition of difference without similarity. It
arises from an act of memory--for the mind must still be able to recall
the past, dimly at least--but from a memory which misses its habitual
support in a recognized element of constancy. If there is no memory,
that is to say, if the past is a complete blank, the mind simply feels a
rupture of identity without any transformation of self. This is our
condition on awaking from a perfectly forgotten period of sleep, or from
a perfectly unconscious state (if such is possible) when induced by
anæsthetics. Such gaps are, as we have seen, easily filled up, and the
sense of identity restored by a kind of retrospective "skipping." On the
other hand, the confusion which arises from too great and violent a
transformation of our _remembered_ experiences is much less easily
corrected. As long as the recollection of the old feelings remains, and
with this the sense of violent contrast between the old and the new
ones, so long will the illusion of two sundered selves tend to recur.

The full development of this process of imaginative fission or cleavage
of self is to be met with in mental disease. The beginnings of such
disease, accompanied as they commonly are with disturbances of bodily
sensations and the recurring emotions, illustrate in a very interesting
way the dependence of the recognition of self on a certain degree of
uniformity in the contents of consciousness. The patient, when first
aware of these changes, is perplexed, and often regards the new feelings
as making up another self, a foreign _Tu_, as distinguished from the
familiar _Ego_. And sometimes he expresses the relation between the old
and the new self in fantastic ways, as when he imagines the former to be
under the power of some foreign personality.

When the change is complete, the patient is apt to think of his former
self as detached from his present, and of his previous life as a kind of
unreal dream; and this fading away of the past into shadowy unreal forms
has, as its result, a curious aberration in the sense of time. Thus, it
is said that a patient, after being in an asylum only one day, will
declare that he has been there a year, five years, and even ten
years.[135] This confusion as to self naturally becomes the
starting-point of illusions of perception; the transformation of self
seeming to require as its logical correlative (for there is a crude
logic even in mental disease) a transformation of the environment. When
the disease is fully developed under the particular form of monomania,
the recollection of the former normal self commonly disappears
altogether, or fades away into a dim image of some perfectly separate
personality. A new ego is now fully substituted for the old. In other
and more violent forms of disease (dementia) the power of connecting the
past and present may disappear altogether, and nothing but the _disjecta
membra_ of an ego remain.

       *       *       *       *       *

Enough has, perhaps, been said to show how much of uncertainty and of
self-deception enters into the processes of memory. This much-esteemed
faculty, valuable and indispensable though it certainly is, can clearly
lay no claim to that absolute infallibility which is sometimes said to
belong to it. Our individual recollection, left to itself, is liable to
a number of illusions even with regard to fairly recent events, and in
the case of remote ones it may be said to err habitually and uniformly
in a greater or less degree. To speak plainly, we can never be certain
on the ground of our personal recollection alone that a distant event
happened exactly in the way and at the time that we suppose. Nor does
there seem to be any simple way by mere reflection on the contents of
our memory of distinguishing what kinds of recollection are likely to be

How, then, it may be asked, can we ever be certain that we are
faithfully recalling the actual events of the past? Given a fairly good,
that is, a cultivated memory, it may be said that in the case of very
recent events a man may feel certain that, when the conditions of
careful attention at the time to what really happened were present, a
distinct recollection is substantially correct. Also it is obvious that
with respect to all repeated experiences our memories afford practically
safe guides. When memory becomes the basis of some item of generalized
knowledge, as, for example, of the truth that the pain of indigestion
has followed a too copious indulgence in rich food, there is little room
for an error of memory properly so called. On the other hand, when an
event is not repeated in our experience, but forms a unique link in our
personal history, the chances of error increase with the distance of the
event; and here the best of us will do well to have resort to a process
of verification or, if necessary, of correction.

In order thus to verify the utterances of memory, we must look beyond
our own internal mental states to some external facts. Thus, the
recollections of our early life may often be tested by letters written
by ourselves or our friends at the time, by diaries, and so on. When
there is no unerring objective record to be found, we may have recourse
to the less satisfactory method of comparing our recollections with
those of others. By so doing we may reach a rough average recollection
which shall at least be free from any individual error corresponding to
that of personal equation in perception. But even thus we cannot be sure
of eliminating all error, since there may be a cause of illusion acting
on all our minds alike, as, for example, the extraordinary nature of the
occurrence, which would pretty certainly lead to a common exaggeration
of its magnitude, etc., and since, moreover, this process of comparing
recollections affords an opportunity for that reading back a present
preconception into the past to which reference has already been made.

The result of our inquiry is less alarming than it looks at first sight.
Knowledge is valuable for action, and error is chiefly hurtful in so far
as it misdirects conduct. Now, in a general way, we do not need to act
upon a recollection of single remote events; our conduct is sufficiently
shaped by an accurate recollection of single recent events, together
with those bundles of recollections of recurring events and sequences of
events which constitute our knowledge of ourselves and our common
knowledge of the world about us. Nature has done commendably well in
endowing us with the means of cultivating our memories up to this point,
and we ought not to blame her for not giving us powers which would only
very rarely prove of any appreciable practical service to us.



The account of the apparent ruptures in our personal identity given in
this chapter may help us to understand the strange tendency to confuse
self with other objects which occasionally appears in waking
consciousness and in dreams. These errors may be said generally to be
due to the breaking up of the composite image of self into its
fragments, and the regarding of certain of these only. Thus, the
momentary occurrence of partial illusion in intense sympathy with
others, including that imaginative projection of self into inanimate
objects, to which reference has already been made, may be said to depend
on exclusive attention to the subjective aspect of self, to the total
disregard of the objective aspect. In other words, when we thus
momentarily "lose ourselves," or merge our own existence in that of
another object, we clearly let drop out of sight the visual
representation of our own individual organism. On the other hand, when
in dreams we double our personality, or represent to ourselves an
external self which becomes the object of visual perception, it is
probably because we isolate in imagination the objective aspect of our
personality from the other and subjective aspect. It is not at all
unlikely that the several confusions of self touched on in this chapter
have had something to do with the genesis of the various historical
theories of a transformed existence, as, for example, the celebrated
doctrine of metempsychosis.



Our knowledge is commonly said to consist of two large
varieties--Presentative and Representative. Representative knowledge,
again, falls into two chief divisions. The first of these is Memory,
which, though not primary or original, like presentative knowledge, is
still regarded as directly or intuitively certain. The second division
consists of all other representative knowledge besides memory,
including, among other varieties, our anticipations of the future, our
knowledge of others' past experience, and our general knowledge about
things. There is no one term which exactly hits off this large sphere of
cognition: I propose to call it Belief. I am aware that this is by no
means a perfect word for my purpose, since, on the one hand, it suggests
that every form of this knowledge must be less certain than presentative
or mnemonic knowledge, which cannot be assumed; and since, on the other
hand, the word is so useful a one in psychology, for the purpose of
marking off the subjective fact of assurance in all kinds of cognition.
Nevertheless, I know not what better one I could select in order to
make my classification answer as closely as a scientific treatment will
allow to the deeply fixed distinctions of popular psychology.

It might at first seem as if perception, introspection, and memory must
exhaust all that is meant by immediate, or self-evident, knowledge, and
as if what I have here called belief must be uniformly mediate,
derivate, or inferred knowledge. The apprehension of something now
present to the mind, externally or internally, and the reapprehension
through the process of memory of what was once so apprehended, might
appear to be the whole of what can by any stretch of language be called
direct cognition of things. This at least would seem to follow from the
empirical theory of knowledge, which regards perception and memory as
the ground or logical source of all other forms of knowledge.

And even if we suppose, with some philosophers, that there are certain
innate principles of knowledge, it seems now to be generally allowed
that these, apart from the particular facts of experience, are merely
abstractions; and that they only develop into complete knowledge when
they receive some empirical content, which must be supplied either by
present perception or by memory. So that in this case, too, all definite
concrete knowledge would seem to be either presentative cognition,
memory, or, lastly, some mode of inference from these.

A little inquiry into the mental operations which I here include under
the name belief will show, however, that they are by no means uniformly
process of inference. To take the simplest form of such knowledge,
anticipation of some personal experience: this may arise quite apart
from recollection, as a spontaneous projection of a mental image into
the future. A person may feel "intuitively certain" that something is
going to happen to him which does not resemble anything in his past
experience. Not only so; even when the expectation corresponds to a bit
of past experience, this source of the expectation may, under certain
circumstances, be altogether lost to view, and the belief assume a
secondarily automatic or intuitive character. Thus, a man may have first
entertained a belief in the success of some undertaking as the result of
a rough process of inference, but afterwards go on trusting when the
grounds for his confidence are wholly lost sight of.

This much may suffice for the present to show that belief sometimes
approximates to immediate, or self-evident, conviction. How far this is
the case will come out in the course of our inquiry into its different
forms. This being so, it will be needful to include in our present study
the errors connected with the process of belief in so far as they
simulate the immediate instantaneous form of illusion.

What I have here called belief may be roughly distinguished into simple
and compound belief. By a simple belief I mean one which has to do with
a single event or fact. It includes simple modes of expectation, as well
as beliefs in single past facts not guaranteed by memory. A compound
belief, on the other hand, has reference to a number of events or facts.
Thus, our belief in the continued existence of a particular object, as
well as our convictions respecting groups or classes of events, must be
regarded as compound, since they can be shown to include a number of
simple beliefs.

A. _Simple Illusory Belief: Expectation._

It will be well to begin our inquiry by examining the errors connected
with simple expectations, so far as these come under our definition of
illusion. And here, following our usual practice, we may set out with a
very brief account of the nature of the intellectual process in its
correct form. For this purpose we shall do well to take a complete or
definite anticipation of an event as our type.[136]

The ability of the mind to move forward, forecasting an order of events
in time, is clearly very similar to its power of recalling events. Each
depends on the capability of imagination to represent a sequence of
events or experiences. The difference between the two processes is that
in anticipation the imagination setting out from the present traces the
succession of experiences in their actual order, and not in the reverse
order. It would thus appear to be a more natural and easy process than
recollection, and observation bears out this conclusion. Any object
present to perception which is associated with antecedents and
consequents with the same degree of cohesion, calls up its consequents
rather than its antecedents. The spectacle of the rising of the sun
carries the mind much more forcibly forwards to the advancing morning
than backwards to the receding night. And there is good reason to
suppose that in the order of mental development the power of distinctly
expecting an event precedes that of distinctly recollecting one. Thus,
in the case of the infant mind, as of the animal intelligence, the
presence of signs of coming events, as the preparation of food, seems to
excite distinct and vivid expectation.[137]

As a mode of assurance, expectation is clearly marked off from memory,
and is not explainable by means of this. It is a fundamentally distinct
kind of conviction. So far as we are capable of analyzing it, we may say
that its peculiarity is its essentially active character. To expect a
thing is to have stirred the active impulses, including the powers of
attention; it is to be on the alert for it, to have the attention
already focussed for it, and to begin to rehearse the actions which the
actual happening of the event--for example, the approach of a welcome
object--would excite. It thus stands in marked contrast to memory, which
is a passive attitude of mind, becoming active only when it gives rise
to the expectation of a recurrence of the event.[138]

And now let us pass to the question whether expectation ever takes the
form of immediate knowledge. It may, perhaps, be objected that the
anticipation of something future cannot be knowledge at all in the sense
in which the perception of something present or the recollection of
something past is knowledge. But this objection, when examined closely,
appears to be frivolous. Because the future fact has not yet come into
the sphere of actual existence, it is none the less the object of a
perfect assurance.[139]

But, even if it is conceded that expectation is knowledge, the objection
may still be urged that it cannot be immediate, since it is the very
nature of expectation to ground itself on memory. I have already hinted
that this is not the case, and I shall now try to show that what is
called expectation covers much that is indistinguishable from immediate
intuitive certainty, and consequently offers room for an illusory form
of error.

Let us set out with the simplest kind of expectation, the anticipation
of something about to happen within the region of our personal
experience, and similar to what has happened before. And let the coming
of the event be first of all suggested by some present external fact or
sign. Suppose, for example, that the sky is heavy, the air sultry, and
that I have a bad headache; I confidently anticipate a thunderstorm. It
would commonly be said that such an expectation is a kind of inference
from the past. I remember that these appearances have been followed by a
thunderstorm very often, and I infer that they will in this new case be
so followed.

To this, however, it may be replied that in most cases there is no
conscious going back to the past at all. As I have already remarked,
anticipation is pretty certainly in advance of memory in early life. And
even after the habit of passing from the past to the future, from memory
to expectation, has been formed, the number of the past repetitions of
experience would prevent the mind's clearly reverting to them. And,
further, the very force of habit would tend to make the transition from
memory to expectation more and more rapid, automatic, and unconscious.
Thus it comes about that all distinctly suggested approaching events
seem to be expected by a kind of immediate act of belief. The present
signs call up the representation of the coming event with all the force
of a direct intuition. At least, it may be said that if a process of
inference, it is one which has the minimum degree of consciousness.

It might still be urged that the mind passes from the _present_ facts as
signs, and so still performs a kind of reasoning process. This is, no
doubt, true, and differentiates expectation from perception, in which
there is no conscious transition from the presented to the represented.
Still I take it that this is only a process of reasoning in so far as
the sign is consciously generalized, and this is certainly not true of
early expectations, or even of any expectations in a wholly uncultivated

For these reasons I think that any errors involved in such an
anticipation may, without much forcing, be brought under our definition
of illusion. When due altogether to the immediate force of suggestion in
a present object or event, and not involving any conscious transition
from past to future, or from general truth to particular instance, these
errors appear to me to have more of the character of illusions than of
that of fallacies.

Much the same thing may be said about the vivid anticipations of a
familiar kind of experience called up by a clear and consecutive verbal
suggestion. When a man, even with an apparent air of playfulness, tells
me that something is going to happen, and gives a consistent consecutive
account of this, I have an anticipation which is not consciously
grounded on any past experience of the value of human testimony in
general, or of this person's testimony in particular, but which is
instantaneous and quasi-immediate. Consequently, any error connected
with the mental act approximates to an illusion.

So far I have supposed that the anticipated event is a recurring one,
that is to say, a kind of experience which has already become familiar
to us. This, however, holds good only of a very few of our experiences.
Our life changes as it progresses, both outwardly and inwardly. Many of
our anticipations, when first formed, involve much more than a
reproduction of a past experience, namely, a complex act of constructive
imagination. Our representations of these untried experiences, as, for
example, those connected with a new set of circumstances, a new social
condition, a new mode of occupation, and so on, are clearly at the first
far from simple processes of inference from the past. They are put
together by the aid of many fragmentary images, restored by distinct
threads of association, yet by a process so rapid as to appear like an
intuition. Indeed, the anticipation of such new experiences more often
resembles an instantaneous imaginative intuition than a process of
conscious transition from old experiences. In the case of these
expectations, then, there would clearly seem to be room for illusion
from the first.

But even supposing that the errors connected with the first formation of
an expectation cannot strictly be called illusory, we may see that such
simple expectation will, in certain cases, tend to grow into something
quite indistinguishable from illusion. I refer to expectations of
_remote_ events which allow of frequent renewal. Even supposing the
expectation to have originated from some rational source, as from a
conscious inference from past experience, or from the acceptance of
somebody's statement, the very habit of cherishing the anticipation
tends to invest it with an automatic self-sufficient character. To all
intents and purposes the prevision becomes intuitive, by which I mean
that the mind is at the time immediately certain that something is going
to happen, without needing to fall back on memory or reflection. This
being so, whenever the initial process of inference or quasi-inference
happens to have been bad, an illusory expectation may arise. In other
words, the force of repetition and habit tends to harden what may, in
its initial form, have resembled a kind of fallacy into an illusion.

And now let us proceed further. When a permanent expectation is thus
formed, there arises the possibility of processes which favour illusion
precisely analogous to those which we have studied in the case of

In the first place, the habit of imagining a future event is attended
with a considerable amount of illusion as to time or remoteness. After
what has been said respecting the conditions of such error in the case
of memory, a very few words will suffice here.

It is clear, then, in the first place, that the mind will tend to
shorten any period of future time, and so to antedate, so to speak, a
given event, in so far as the imagination is able clearly and easily to
run over its probable experiences. From this it follows that repeated
forecastings of series of events, by facilitating the imaginative
process, tend to beget an illusory appearance of contraction in the time
anticipated. Moreover, since in anticipation so much of each division of
the future time-line is unknown, it is obviously easy for the expectant
imagination to skip over long intervals, and so to bring together widely
remote events.

In addition to this general error, there are more special errors. As in
the case of recollection, vividness of mental image suggests
propinquity; and accordingly, all vivid anticipations, to whatever cause
the vividness may be owing, whether to powerful suggestion on the part
of external objects, to verbal suggestion, or to spontaneous imagination
and feeling, are apt to represent their objects as too near.

It follows that an event intensely longed for, in so far as the
imagination is busy in representing it, will seem to approach the
present. At the same time, as we have seen, an event much longed for
commonly appears to be a great while coming, the explanation being that
there is a continually renewed contradiction between anticipation and
perception. The self-adjustment of the mind in the attitude of
expectant attention proves again and again to be vain and futile, and it
is this fact which brings home to it the slowness of the sequences of
perceived fact, as compared with the rapidity of the sequences of

When speaking of the retrospective estimate of time, I observed that the
apparent distance of an event depends on our representation of the
intervening time-segment. And the same remark applies to the prospective
estimate. Thus, an occurrence which we expect to happen next week will
seem specially near if we know little or nothing of the contents of the
intervening space, for in this case the imagination does not project the
experience behind a number of other distinctly represented events.

Finally, it is to be remarked that the prospective appreciation of any
duration will tend to err relatively by way of excess, where the time is
exceptionally filled out with clearly expected and deeply interesting
experiences. To the imagination of the child, a holiday, filled with new
experiences, appears to be boundless.

Thus far I have assumed that the date of the future event is a matter
which might be known. It is, however, obvious, from the very nature of
knowledge with respect to the future, that we may sometimes be certain
of a thing happening to us without knowing with any degree of
definiteness when it will happen. In the case of these temporally
undefined expectations, the law already expounded holds good that all
vividness of representation tends to lend the things represented an
appearance of approaching events. On the other hand, there are some
events, such as our own death, which our instinctive feelings tend to
banish to a region so remote as hardly to be realized at all.

So much with respect to errors in the localizing of future events.

In the second place, a habit of imagining a future event or group of
events will give play to those forces which tend to transform a mental
image. In other words, the habitual indulgence of a certain anticipation
tends to an illusory view, not only of the "when?" but also of the
"how?" of the future event. These transformations, due to subtle
processes of emotion and intellect, and reflecting the present habits of
these, exactly resemble those by which a remembered event becomes
gradually transformed. Thus, we carry on our present habits of thought
and feeling into the remote future, foolishly imagining that at a
distant period of life, or in greatly altered circumstances, we shall
desire and aim at the same things as now in our existing circumstances.
In close connection with this forward projection of our present selves,
there betrays itself a tendency to look on future events as answering to
our present desires and aspirations. In this way, we are wont to soften,
beautify, and idealize the future, marking it off from the hard
matter-of-fact present.

The less like the future experience to our past experience, or the more
remote the time anticipated, the greater the scope for such imaginative
transformation. And from this stage of fanciful transformation of a
future reality to the complete imaginative creation of such a reality,
the step is but a small one. Here we reach the full development of
illusory expectation, that which corresponds to hallucination in the
region of sense-perception.

In order to understand these extreme forms of illusory expectation, it
will be necessary to say something more about the relation of
imagination to anticipation in general. There are, I conceive, good
reasons for saying that any kind of vivid imagination tends to pass into
a semblance of an expectation of a coming personal experience, or an
event that is about to happen within the sphere of our own observation.
It has long been recognized by writers, among whom I may mention Dugald
Stewart, that to distinctly imagine an event or object is to feel for
the moment a degree of belief in the corresponding reality. Now, I have
already said that expectation is probably a more natural and an earlier
developed state of mind than memory. And so it seems probable that any
mental image which happens to take hold on the mind, if not recognized
as one of memory, or as corresponding to a fact in somebody else's
experience, naturally assumes the form of an expectation of a personal
experience. The force of the expectation will vary in general as the
vividness and persistence of the mental image. Moreover, it follows,
from what has been said, that this force of imagination will determine
what little time-character we ever give to these wholly ungrounded

We see, then, that any process of spontaneous imagination will tend to
beget some degree of illusory expectation. And among the agencies by
which such ungrounded imagination arises, the promptings of feeling play
the most conspicuous part. A present emotional excitement may give to an
imaginative anticipation, such as that of the prophetic enthusiast, a
reality which approximates to that of an actually perceived object. And
even where this force of excitement is wanting, a gentle impulse of
feeling may suffice to beget an assurance of a distant reality. The
unknown recesses of the remote future offer, indeed, the field in which
the illusory impulses of our emotional nature have their richest

  "Thus, from afar, each dim discover'd scene
   More pleasing seems than all the past hath been;
   And every form, that Fancy can repair
   From dark oblivion, glows divinely there."

The recurring emotions, the ruling aspirations, find objects for
themselves in this veiled region. Feelings too shy to burst forth in
unseemly anticipation of the immediate future, modestly satisfy
themselves with this remote prospect of satisfaction. And thus, there
arises the half-touching, half-amusing spectacle of men and women
continually renewing illusory hopes, and continually pushing the date of
their realization further on as time progresses and brings no actual

So far I have spoken of such expectations as refer to future personal
experience only. Growing individual experience and the enlargement of
this by the addition of social experience enable us to frame a number of
other beliefs more or less similar to the simple expectations just dealt
with. Thus, for example, I can forecast with confidence events which
will occur in the lives of others, and which I shall not even witness;
or again, I may even succeed in dimly descrying events, such as
political changes or scientific discoveries, which will happen after my
personal experience is at an end. Once more, I can believe in something
going on now at some distant and even inaccessible point of the
universe, and this appears to involve a conditional expectation, and to
mean that I am certain that I or anybody else would see the phenomenon,
if we could at this moment be transported to the spot.

All such previsions are supposed to be formed by a process of inference
from personal experience, including the trustworthiness of testimony.
Even allowing, however, that this was so in the first stages of the
belief, it is plain that, by dint of frequent renewal, the expectation
would soon cease to be a process of inference, and acquire an apparently
self-evident character. This being so, if the expectation is not
adequately grounded to start with, it is very likely to develop into an
illusion. And it is to be added that these permanent anticipations may
have their origin much more in our own wishes or emotional promptings
than in fact and experience. The mind undisciplined by scientific
training is wont to entertain numerous beliefs of this sort respecting
what is now going on in unvisited parts of the world, or what will
happen hereafter in the distant future. The remote, and therefore
obscure, in space and in time has always been the favourite region for
the projection of pleasant fancies.

Once more, besides these oblique kinds of expectation, I may form other
seemingly simple beliefs, to which the term expectation seems less
clearly applicable. Thus, on waking in the morning and finding the
ground covered with snow, my imagination moves backwards, as in the
process of memory, and realizes the spectacle of the softly falling
snow-flakes in the hours of the night. The oral communication of others'
experience, including the traditions of the race, enables me to set out
from any present point of time, and reconstruct complex chains of
experience of vast length lying beyond the bounds of my own personal

I need not here discuss what the exact nature of such beliefs is. J.S.
Mill identifies them with expectations. Thus, according to him, my
belief in the nocturnal snowstorm is the assurance that I should have
seen it had I waited up during the night. So my belief in Cicero's
oratory resolves itself into the conviction that I should have heard
Cicero under certain conditions of time and place, which is identical
with my expectation that I shall hear a certain speaker to-morrow if I
go to the House of Commons.[140] However this be, the thing to note is
that such retrospective beliefs, when once formed, tend to approximate
in character to recollections. This is true even of new beliefs in
recent events directly made known by present objective consequences or
signs, as the snowstorm. For in this case there is commonly no conscious
comparison of the present signs with previously known signs, but merely
a direct quasi-mnemonic passage of mind from the present fact to its
antecedent. And it is still more true of long-entertained retrospective
beliefs. When, for example, the original grounds of an historical
hypothesis are lost sight of, and after the belief has hardened and
solidified by time, it comes to look much more like a recollection than
an expectation. As a matter of fact, we have seen, when studying the
illusions of memory, that our personal experience does become confused
with that of others. And one may say that all long-cherished
retrospective beliefs tend to become assimilated to recollections.

Here then, again, there seems to be room for illusion to arise. Even in
the case of a recent past event, directly made known by present
objective signs, the mind is liable to err just as in the case of
forecasting an immediately approaching event. And such error has all the
force of an illusion: its contradiction is almost as great a shock as
that of a recollection. When, for example, I enter my house, and see a
friend's card lying on the table, I so vividly represent to myself the
recent call of my friend, that when I learn the card is an old one which
has accidentally been put on the table, I experience a sense of
disillusion very similar to that which attends a contradicted
perception. The early crude stages of physical science abundantly
illustrate the genesis of such illusions.

It may be added that if there be any feeling present in the mind at the
time, the barest suggestion of something having happened will suffice to
produce the immediate assurance. Thus, an angry person is apt to hastily
accuse another of having done certain things on next to no evidence. The
love of the marvellous seems to have played a conspicuous part in
building up and sustaining the fanciful hypotheses which mark the dawn
of physical science.

Verbal suggestion is a common mode of producing this semblance of a
recollected event. By means of the narrative style, it vividly suggests
the idea that the events described belong to the past, and excites the
imagination to a retrospective construction of them as though they were
remembered events. Hence the power of works of fiction on the ordinary
mind. Even when there is no approach to an illusion of perception, or to
one of memory in the strict sense, the reading of a work of fiction
begets at the moment a retrospective belief that has a certain
resemblance to a recollection.

All such illusions as those just illustrated, if not afterwards
corrected, tend to harden into yet more distinctly "intuitive" errors.
Thus, for example, one of the crude geological hypotheses, of which Sir
Charles Lyell tells us,[141] would, by the mere fact of being kept
before the mind, tend to petrify into a hard fixed belief. And this
process of hardening is seen strikingly illustrated in the case of
traditional errors, especially when these fall in with our own emotional
propensities. Our habitual representations of the remote historical past
are liable to much the same kind of error as our recollections of early
personal experience. The wrong statements of others and the promptings
of our own fancies may lead in the first instance to a filling up of the
remote past with purely imaginary shapes. Afterwards the particular
origin of the belief is forgotten, and the assurance assumes the aspect
of a perfectly intuitive conviction. The hoary traditional myths
respecting the golden age, and so on, and the persistent errors of
historians under the sway of a strong emotional bias, illustrate such

So much as to simple illusions of belief, or such as involve single
representations only. Let us now pass to compound illusions, which
involve a complex group of representations.

B. _Compound Illusory Belief._

A familiar example of a compound belief is the belief in a permanent or
persistent individual object of a certain character. Such an idea,
whatever its whole meaning may be--and this is a disputed point in
philosophy--certainly seems to include a number of particular
representations, corresponding to direct personal recollections, to the
recollections of others, and to numerous anticipations of ourselves and
of others. And if the object be a living creature endowed with feelings,
our idea of it will contain, in addition to these represented
perceptions of ourselves or of others, a series of represented insights,
namely, such as correspond to the inner experience of the being, so far
as this is known or imagined.

It would thus seem that the idea which we habitually carry about with us
respecting a complex individual object is a very composite idea. In
order to see this more fully, let us inquire into what is meant by our
belief in a person. My idea of a particular friend contains, among other
things, numbers of vague representations of his habitual modes of
feeling and acting, and numbers of still more vague expectations of how
he will or might feel and act in certain circumstances.

Now, it is plain that such a composite idea must have been a very slow
growth, involving, in certain stages of its formation, numerous
processes of inference or quasi-inference from the past to the future.
But in process of time these elements fuse inseparably: the directly
known and the inferred no longer stand apart in my mind; my whole
conception of the individual as he has been, is, and will be, seems one
indivisible cognition; and this cognition is so firmly fixed and
presents itself so instantaneously to the mind when I think of the
object, that it has all the appearance of an intuitive conviction.

If this is a fairly accurate description of the structure of these
compound representations and of their attendant beliefs, it is easy to
see how many openings for error they cover. To begin with, my
representation of so complex a thing as a concrete personality must
always be exceedingly inadequate and fragmentary. I see only a few
facets of the person's many-sided mind and character. And yet, in
general, I am not aware of this, but habitually identify my
representation with the totality of the object.

More than this, a little attention to the process by which these
compound beliefs arise will disclose the fact that this apparently
adequate representation of another has arisen in part by other than
logical processes. If the blending of memory and expectation were simply
a mingling of facts with correct inferences from these, it might not
greatly matter; but it is something very different from this. Not only
has our direct observation of the person been very limited, even that
which we have been able to see has not been perfectly mirrored in our
memory. It has already been remarked that recollection is a selective
process, and this truth is strikingly illustrated in the growth of our
enduring representations of things. What stamps itself on my memory is
what surprised me or what deeply interested me at the moment. And then
there are all the risks of mnemonic illusion to be taken into account as
well. Thus, my idea of a person, so far even as it is built up on a
basis of direct personal recollection, is essentially a fragmentary and
to some extent a misleading representation.

Nor is this all. My habitual idea of a person is a resultant of forces
of memory conjoined with other forces. Among these are to be reckoned
the influence of illusory perception or insight, my own and that of
others. The amount of misinterpretation of the words and actions of a
single human being during the course of a long acquaintance must be very
considerable. To these must be added the effect of erroneous single
expectations and reconstructions of past experiences, in so far as these
have not been distinctly contradicted and dissipated. All these errors,
connected with single acts of observing or inferring the feelings and
doings of another, have their effect in distorting the subsequent total
representation of the person.

Finally, we must include a more distinct ingredient of active illusion,
namely, all the complex effects of the activity of imagination as led,
not by fact and experience, but by feeling and desire. Our permanent
idea of another reflects all that we have fondly imagined the person
capable of doing, and thus is made up of an ideal as well as a real
actually known personality. And this result of spontaneous imagination
must be taken to include the ideals entertained by others who are likely
to have influenced us by their beliefs.[142]

Enough has probably been said to show how immensely improbable it is
that our permanent cognition of so complex an object as a particular
human being should be at all an accurate representation of the reality,
how much of the erroneous is certain to get mixed up with the true. And
this being so, we may say that our apparently simple direct cognition of
a given person, our assurance of what he is and will continue to be, is
to some extent illusory.

_Illusion of Self-Esteem._

Let us now pass to another case of compound representation, where the
illusory element is still more striking. I refer to the idea of self
which each of us habitually carries about with him. Every man's opinion
of himself, as a whole, is a very complex mental product, in which facts
known by introspection no doubt play a part, but probably only a very
subordinate part. It is obvious, from what has been said about the
structure of our habitual representations of other individuals, that our
ordinary representation of ourselves will be tinged with that mass of
error which we have found to be connected with single acts of
introspection, recollections of past personal experience, and illusory
single expectations of future personal experiences. How large an opening
for erroneous conviction here presents itself can only be understood by
a reference to certain deeply fixed impulses and feelings connected
with, the very consciousness of self, and favouring what I have marked
off as active illusion. I shall try to show very briefly that each man's
intuitive persuasion of his own powers, gifts, or importance--in brief,
of his own particular value, contains, from the first, a palpable
ingredient of active illusion.

Most persons, one supposes, have with more or less distinct
consciousness framed a notion of their own value, if not to the world
generally, at least to themselves. And this notion, however undefined it
may be, is held to with a singular tenacity of belief. The greater part
of mankind, indeed, seem never to entertain the question whether they
really possess points of excellence. They assume it as a matter
perfectly self-evident, and appear to believe in their vaguely conceived
worth on the same immediate testimony of consciousness by which they
assure themselves of their personal existence. Indeed, the conviction of
personal consequence may be said to be a constant factor in most men's
consciousness. However restrained by the rules of polite intercourse, it
betrays its existence and its energy in innumerable ways. It displays
itself most triumphantly when the mind is suddenly isolated from other
minds, when other men unite in heaping neglect and contempt on the
believer's head. In these moments he proves an almost heroic strength of
confidence, believing in himself and in his claims to careful
consideration when all his acquaintance are practically avowing their

The intensity of this belief in personal value may be observed in very
different forms. The young woman who, quite independently of others'
opinion, and even in defiance of it, cherishes a conviction that her
external attractions have a considerable value; the young man who, in
the face of general indifference, persists in his habit of voluble talk
on the supposition that he is conferring on his fellow-creatures the
fruits of profound wisdom; and the man of years whose opinion of his own
social importance and moral worth is quite disproportionate to the
estimation which others form of his claims--these alike illustrate the
force and pertinacity of the belief.

There are, no doubt, many exceptions to this form of self-appreciation.
In certain robust minds, but little given to self-reflection, the idea
of personal value rarely occurs. And then there are timid, sensitive
natures that betray a tendency to self-distrust of all kinds, and to an
undue depreciation of personal merit. Yet even here traces of an impulse
to think well of self will appear to the attentive eye, and one can
generally recognize that this impulse is only kept down by some other
stronger force, as, for example, extreme sensitiveness to the judgment
of others, great conscientiousness, and so on. And however this be, it
will be allowed that the average man rates himself highly.

It is to be noticed that this persuasion of personal value or excellence
is, in common, very vague. A man may have a general sense of his own
importance without in the least being able to say wherein exactly his
superiority lies. Or, to put it another way, he may have a strong
conviction that he stands high in the scale of morally deserving
persons, and yet be unable to define his position more nearly. Commonly,
the conviction seems to be only definable as an assurance of a
superlative of which the positive and comparative are suppressed. At
most, his idea of his moral altitude resolves itself into the
proposition, "I am a good deal better than Mr. A. or Mr. B." Now, it is
plain that in these intuitive judgments on his own excellence, the man
is making an assertion with respect, not only to inner subjective
feelings which he only can be supposed to know immediately, but also to
external objective facts which are patent to others, namely, to certain
active tendencies and capabilities, to the direction of external conduct
in certain lines.[143] Hence, if the assertion is erroneous, it will be
in plain contradiction to others' perceptions of his powers or moral
endowments. And this is what we actually find. A man's self-esteem, in a
large preponderance of cases, is plainly in excess of others' esteem of
him. What the man conceives himself to be differs widely from what
others conceive him to be.

  "Oh wad some power the giftie gie us,
   To see oursels as others see us!"

Now, whence comes this large and approximately uniform discrepancy
between our self-esteem and others' esteem of us? By trying to answer
this question we shall come to understand still better the processes by
which the most powerful forms of illusion are generated.

It is, I think, a matter of every-day observation that children manifest
an apparently instinctive disposition to magnify self as soon as the
vaguest idea of self is reached. It is very hard to define this feeling
more precisely than by terming it a rudimentary sense of personal
importance. It may show itself in very different ways, taking now a more
active form, as an impulse of self-assertion, and a desire to enforce
one's own will to the suppression of others' wills, and at another time
wearing the appearance of a passive emotion, an elementary form of
_amour propre_. And it is this feeling which forms the germ of the
self-estimation of adults. For in truth all attribution of value
involves an element of feeling, as respect, and of active desire, and
the ascription of value to one's self is in its simplest form merely the
expression of this state of mind.

But how is it, it may be asked, that this feeling shows itself
instinctively as soon as the idea of self begins to arise in
consciousness? The answer to this question is to be found, I imagine, in
the general laws of mental development. All practical judgments like
that of self-estimation are based on some feeling which is developed
before it; and, again, the feeling itself is based on some instinctive
action which, in like manner, is earlier than the feeling. Thus, for
example, an Englishman's judgment that his native country is of
paramount value springs out of a long-existent sentiment of patriotism,
which sentiment again may be regarded as having slowly grown up about
the half-blindly followed habit of defending and furthering the
interests of one's nation or tribe. In a similar way, one suspects, the
feeling of personal worth, with its accompanying judgment, is a product
of a long process of instinctive action.

What this action is it is scarcely necessary to remind the reader. Every
living organism strives, or acts as if it consciously strove, to
maintain its life and promote its well-being. The actions of plants are
clearly related to the needs of a prosperous existence, individual first
and serial afterwards. The movements of the lower animals have the same
end. Thus, on the supposition that man has been slowly evolved from
lower forms, it is clear that the instinct of self-promotion must be the
deepest and most ineradicable element of his nature, and it is this
instinct which directly underlies the rudimentary sentiment of
self-esteem of which we are now treating.

This instinct will appear, first of all, as the unreflecting organized
habit of seeking individual good, of aiming at individual happiness, and
so of pushing on the action of the individual will. This impulse shows
itself in distinct form as soon as the individual is brought into
competition with another similarly constituted being. It is the force
which displays itself in all opposition and hostility, and it tends to
limit and counteract the gregarious instincts of the race. In the next
place, as intelligence expands, this instinctive action becomes
conscious pursuit of an end, and at this stage the thing pursued
attracts to itself a sentiment. The individual now consciously desires
his own happiness as contrasted with that of others, knowingly aims at
enlarging his own sphere of action to the diminution of others' spheres.
Here we have the nascent sentiment of self-esteem, on which all later
judgments respecting individual importance are, in part at least,

Thus, we see that long before man had arrived at an idea of self there
had been growing up an emotional predisposition to think well of self.
And in this way we may understand how it is that this sentiment of
self-esteem shows itself immediately and instinctively in the child's
mind as soon as its unfolding consciousness is strong enough to grasp
the first rough idea of personal existence. Far down, so to speak, below
the surface of distinct consciousness, in the intricate formation of
ganglion-cell and nerve-fibre, the connections between the idea of self
and this emotion of esteem have been slowly woven through long ages of
animal development.

Here, then, we seem to have the key to the apparently paradoxical fact
that a man, with all his superior means of studying his own feelings,
commonly esteems himself, in certain respects at least, less accurately
than a good external observer would be capable of doing. In forming an
opinion of ourselves we are exposed to the full force of a powerful
impulse of feeling. This impulse, acting as a bias, enters more or less
distinctly into our single acts of introspection, into our attempts to
recall our past doings, into our insights into the meaning of others'
words and actions as related to ourselves (forming the natural
disposition to enjoy flattery), and finally into our wild dreams as to
our future achievements. It is thus the principal root of that gigantic
illusion of self-conceit, which has long been recognized by practical
sense as one of the greatest obstacles to social action; and by art as
one of the most ludicrous manifestations of human weakness.

If there are all these openings for error in the beliefs we go on
entertaining respecting individual things, including ourselves, there
must be a yet larger number of such openings in those still more
compound beliefs which we habitually hold respecting collections or
classes of things. A single illusion of perception or of memory may
suffice to give rise to a wholly illusory belief in a class of objects,
for example, ghosts. The superstitious beliefs of mankind abundantly
illustrate this complexity of the sources of error. And in the case of
our every-day beliefs respecting real classes of objects, these sources
contribute a considerable quota of error. We may again see this by
examining our ordinary beliefs respecting our fellow-men.

A moment's consideration will show that our prevailing views respecting
any section of mankind, say our fellow-countrymen, or mankind at large,
correspond at best to a very loose process of reasoning. The accidents
of our personal experience and opportunities of observation, the
traditions which coloured our first ideas, the influence of our dominant
feelings in selecting for attention and retention certain aspects of the
complex object, and in idealizing this object,--these sources of passive
and active illusion, must, to say the least, have had as much to do with
our present solidified and seemingly "intuitive" knowledge as anything
that can be called the exercise of individual judgment and reasoning

The force of this observation and the proof that such widely generalized
beliefs are in part illusory, is seen in the fact that men of unlike
experience and unlike temperament form such utterly dissimilar views of
the same object. Thus, as Mr. Spencer has shown,[144] in looking at
things national there may be not only a powerful patriotic bias at work
in the case of the vulgar Philistine, but also a distinctly
anti-patriotic bias in the case of the over-fastidious seeker after
culture. And I need hardly add that the different estimates of mankind
held with equal assurance by the cynic, the misanthropist, and the
philanthropic vindicator of his species, illustrate a like diversity of
the psychological conditions of belief.

Finally, illusion may enter into that still wider collection of beliefs
which make up our ordinary views of life and the world as a whole. Here
there reflect themselves in the plainest manner the accidents of our
individual experience and the peculiar errors to which our intellectual
and emotional conformation disposes us. The world is for us what we feel
it to be; and we feel it to be the cause of our particular emotional
experience. Just as we have found that our environment helps to
determine our idea of self and personal continuity, so, conversely, our
inner experience, our remembered or imagined joys and sorrows throw a
reflection on the outer world, giving it its degree of worth. Hence the
contradictory, and consequently to some extent at least illusory, views
of the optimist and the pessimist, "intuitions" which, I have tried to
show elsewhere, are connected with deeply rooted habits of feeling, and
are antecedent to all reasoned philosophic systems.

If proof were yet wanted that these wide-embracing beliefs may to some
extent be illusory, it would be found in the fact that they can be
distinctly coloured by a temporary mood or mental tone. As I have more
than once had occasion to remark, a feeling when present tends to colour
all the ideas of the time. And when out of sorts, moody, and
discontented, a man is prone to find a large objective cause of his
dissatisfaction in a world out of joint and not moving to his mind.

It is evident that all the permanent beliefs touched on in this chapter
must constitute powerful predispositions with respect to any particular
act of perception, insight, introspection, or recollection. In other
words, these persistent beliefs, so far as individual or personal, are
but another name for those fixed habits of mind which, in the case of
each one of us, constitute our intellectual bias, and the source of the
error known as personal equation. And it may be added that, just as
these erroneous beliefs existing in the shape of fixed prejudices
constitute a bias to new error, so they act as powerful resisting forces
in relation to new truth and the correction of error.

In comparing these illusions of belief with those of perception and
memory, we cannot fail to notice their greater compass or range, in
other words, the greater extent of the region of fact misrepresented.
Even if they are less forcible and irresistible than these errors, they
clearly make up for this by the area which they cover.

Another thing to be observed with respect to these comprehensive beliefs
is that where, as here, so many co-operant conditions are at work, the
whole amount of common objective agreement is greatly reduced. In other
words, individual peculiarities of intellectual conformation, emotional
temperament, and experience have a far wider scope for their influence
in these beliefs than they have in the case of presentative cognitions.
At the same time, it is noteworthy that error much more rapidly
propagates itself here than in the case of our perceptions or
recollections. As we have seen, these beliefs all include much more than
the results of the individual's own experience. They offer a large field
for the influence of personal ascendency, of the contagion of sympathy,
and of authority and tradition. As a consequence of this, the illusions
of belief are likely to be far more persistent than those of perception
or of memory; for not only do they lose that salutary process of
correction which comparison with the experience of others affords, but
they may even be strengthened and upheld to some extent by such social

And here the question might seem to obtrude itself, whether, in relation
to such a fluctuating mass of belief as that just reviewed, in which
there appears to be so little common agreement, we can correctly speak
of anything as objectively determinable. If illusion and error as a
whole are defined by a reference to what is commonly held true and
certain, what, it may be asked, becomes of the so-called illusions of

This question will have to be fully dealt with in the following chapter.
Here it may be sufficient to remark that amid all this apparent
deviation of belief from a common standard of truth, there is a clear
tendency to a rational consensus. Thought, by disengaging what is really
matter of permanent and common cognition, both in the individual and
still more in the class,[145] and fixing this quantum of common
cognition in the shape of accurate definitions and universal
propositions, is ever fighting against and restraining the impulses of
individual imagination towards dissociation and isolation of belief. And
this same process of scientific control of belief is ever tending to
correct widespread traditional forms of error, and to erect a new and
better standard of common cognition.

This scientific regulation of belief only fails where the experiences
which underlie the conceptions are individual, variable, and subjective.
Hence there is no definite common conception of the value of life and of
the world, just because the estimate of this value must vary with
individual circumstances, temperament, etc. All that can be looked for
here in the way of a common standard or norm is a rough average
estimate. And this common-sense judgment serves practically as a
sufficient criterion of truth, at least in relation to such extreme
one-sidedness of view as approaches the abnormal, that is to say, one of
the two poles of irrational exaltation, or "joy-madness," and abject
melancholy, which, appear among the phenomena of mental disease.[146]



The foregoing study of illusions may not improbably have had a
bewildering effect on the mind of the reader. To keep the mental eye,
like the bodily eye, for any time intently fixed on one object is apt to
produce a feeling of giddiness. And in the case of a subject like
illusion, the effect is enormously increased by the disturbing character
of the object looked at. Indeed, the first feeling produced by our
survey of the wide field of illusory error might be expressed pretty
accurately by the despondent cry of the poet--

  "Alas! it is delusion all:
   The future cheats us from afar,
   Nor can we be what we recall,
   Nor dare we think on what we are."

It must be confessed that our study has tended to bring home to the mind
the wide range of the illusory and unreal in our intellectual life. In
sense-perception, in the introspection of the mind's own feelings, in
the reading of others' feelings, in memory, and finally in belief, we
have found a large field for illusory cognition. And while illusion has
thus so great a depth in the individual mind, it has a no less striking
breadth or extent in the collective human mind. No doubt its grosser
forms manifest themselves most conspicuously in the undisciplined mind
of the savage and the rustic; yet even the cultivated mind is by no
means free from its control. In truth, most of the illusions illustrated
in this work are such as can be shared in by all classes of mind.

In view of this wide far-reaching area of ascertained error, the mind
naturally asks, What are the real limits of illusory cognition, and how
can we be ever sure of having got beyond them? This question leads us on
to philosophical problems of the greatest consequence, problems which
can only be very lightly touched in this place. Before approaching
these, let us look back a little more carefully and gather up our
results, reflect on the method which we have been unconsciously
adopting, and inquire how far this scientific mode of procedure will
take us in determining what is the whole range of illusory cognition.

We have found an ingredient of illusion mixed up with all the popularly
recognized forms of immediate knowledge. Yet this ingredient is not
equally conspicuous in all cases. First of all, illusion varies very
considerably in its degree of force and persistence. Thus, in general, a
presentative illusion is more coercive than a representative; an
apparent reality present to the mind is naturally felt to be more
indubitable than one absent and only represented. On the other hand, a
representative illusion is often more enduring than a presentative, that
is to say, less easily found out. It is to be added that a good deal of
illusion is only partial, there being throughout an under-current of
rational consciousness, a gentle play of self-criticism, which keeps the
error from developing into a perfect self-delusion. This remark applies
not only to the innocent illusions of art, but also to many of our
every-day illusions, both presentative and representative. In many
cases, indeed, as, for example, in looking at a reflection in a mirror,
the illusion is very imperfect, remaining in the nascent stage.

Again, a little attention to the facts here brought together will show
that the proportion of illusory to real knowledge is far from being the
same in each class of immediate or quasi-immediate cognition. Thus, with
respect to the great distinction between presentative and representative
knowledge, it is to be observed that, in so far as any act of cognition
is, strictly speaking, presentative, it does not appear to admit of
error. The illusions of perception are connected with the representative
side of the process, and are numerous just because this is so extensive.
On the other hand, in introspection, where the scope of independent
representation is so limited, the amount of illusion is very
inconsiderable, and may in practice be disregarded. So again, to take a
narrower group of illusions, we find that in the recalling of distant
events the proportion of error is vastly greater than in the recalling
of near events.

So much as to the extent of illusion as brought to light by our
preceding study. Let us now glance at the conclusions obtained
respecting its nature and its causes.

_Causes of Illusion._

Looking at illusion as a whole, and abstracting from the differences of
mental mechanism in the processes of perception, memory, etc., we may
say that the _rationale_ or mode of genesis of illusion is very much the
same throughout. Speaking broadly, one may describe all knowledge as a
correspondence of representation with fact or experience, or as a stable
condition of the representation which cannot be disturbed by new
experiences. It does not matter, for our present purpose, whether the
fact represented is supposed to be directly present, as in presentative
cognition; or to be absent, either as something past or future, or
finally as a "general fact," that is to say, the group of facts (past
and future) embodied in a universal proposition.[147]

In general this accordance between our representations and facts is
secured by the laws of our intellectual mechanism. It follows from the
principles of association that our simple experiences, external and
internal, will tend to reflect themselves in perception, memory,
expectation, and general belief, in the very time-connections in which
they actually occur. To put it briefly, facts which occur together will
in general be represented together, and they will be the more perfectly
co-represented in proportion to the frequency of this concurrence.

Illusion, as distinguished from correct knowledge, is, to put it
broadly, deviation of representation from fact. This is due in part to
limitations and defects in the intellectual mechanism itself, such as
the imperfections of the activities of attention, discrimination, and
comparison, in relation to what is present. Still more is it due to the
control of our mental processes by association and habit. These forces,
which are at the very root of intelligence, are also, in a sense, the
originators of error. Through the accidents of our experience or the
momentary condition of our reproductive power, representations get
wrongly grouped with presentations and with one another; wrongly
grouped, that is to say, according to a perfect or ideal standard,
namely, that the grouping should always exactly agree with the order of
experience as a whole, and the force of cohesion be proportionate to the
number of the conjunctions of this experience.

This great source of error has been so abundantly illustrated under the
head of Passive Illusions that I need not dwell on it further. It is
plain that a passive error of perception, or of expectation, is due in
general to a defective grouping of elements, to a grouping which
answers, perhaps, to the run of the individual's actual experience, but
not to a large and complete common experience.[148] Similarly, an
illusory general belief is plainly a welding together of elements (here
concepts, answering to innumerable representative images) in
disagreement with the permanent connections of experience. Even a
passive illusion of memory, in so far as it involves a rearrangement of
successive representations, shows the same kind of defect.

In the second place, this incorrect grouping maybe due, not to defects
in attention and discrimination, combined with insufficiently grounded
association, but to the independent play of constructive imagination and
the caprices of feeling. This is illustrated in what I have called
Active Illusions, whether the excited perceptions and the hallucinations
of sense, or the fanciful projections of memory or of expectation. Here
we have a force directly opposed to that of experience. Active illusion
arises, not through the imperfections of the intellectual mechanism, but
through a palpable interference with this mechanism. It is a regrouping
of elements which simulates the form of a suggestion by experience, but
is, in reality, the outcome of the individual mind's extra-intellectual

We see, then, that, in spite of obvious differences in the form, the
process in all kinds of immediate cognition is fundamentally identical.
It is essentially a bringing together of elements, whether similar or
dissimilar and associated by a link of contiguity, and a viewing of
these as connected parts, of a whole; it is a process of synthesis. And
illusion, in all its forms, is bad grouping or carelessly performed
synthesis. This holds good even of the simplest kinds of error in which
a presentative element is wrongly classed; and it holds good of those
more conspicuous errors of perception, memory, expectation, and compound
belief, in which representations connect themselves in an order not
perfectly answering to the objective order.

This view of the nature and causes of illusion is clearly capable of
being expressed in physical language. Bad grouping of psychical elements
is equivalent to imperfect co-ordination of their physical, that is to
say, nervous, conditions, imperfect in the evolutionist's sense, as not
exactly according with external relations. So far as illusions of
suggestion (passive illusions) are concerned, the error is connected
with organized tendencies, due to a limited action of experience. On the
other hand, illusions of preconception (active illusions) usually
involve no such deeply fixed or permanent organic connections, but
merely a temporary confluence of nerve-processes.[149] The nature of the
physical process is best studied in the case of errors of
sense-perception. Yet we may hypothetically argue that even in the case
of the most complex errors, as those of memory and of belief, there is
implied a deviation in the mode of connection of nervous structures
(whether the connection be permanent or temporary) from the external
order of facts.

And now we are in a position to see whether illusion is ultimately
distinguishable from other modes of error, namely, those incident to
conscious processes of reasoning. It must have been plain to an
attentive reader throughout our exposition that, in spite of our
provisional distinction, no sharp line can be drawn between much of
what, on the surface, looks like immediate knowledge, and consciously
derived or inferred knowledge. On its objective side, reasoning may be
roughly defined as a conscious transition of mind from certain facts or
relations of facts to other facts or relations recognized as similar.
According to this definition, a fallacy would be a hasty, unwarranted
transition to new cases not identical with the old. And a good part of
immediate knowledge is fundamentally the same, only that here, through
the exceptional force of association and habit, the transition is too
rapid to be consciously recognized. Consequently, illusion becomes
identified at bottom with fallacious inference: it may be briefly
described as collapsed inference. Thus, illusory perception and
expectation are plainly a hasty transition of mind from old to new, from
past to present, conjunctions of experience.[150] And, as we have seen,
an illusory general belief owes its existence to a coalescence of
representations of known facts or connections with products of
imagination which simulate the appearance of inferences from these

In the case of memory, in so far as it is not aided by reasoning from
present signs, there seems to be nothing like a movement of inference.
It is evident, indeed, that memory is involved in and underlies every
such transition of thought. Illusions of memory illustrate rather a
process of wrong classing, that is to say, of wrongly identifying the
present mental image with past fact, which is the initial step in all
inference. In this way they closely resemble those slight errors of
perception which are due to erroneous classing of sense-impressions. But
since the intellectual process involved in assimilating mental elements
is very similar to that implied in assimilating complex groups of such
elements, we may say that even in these simple kinds of error there is
something which resembles a wrong classing of relations, something,
therefore, which approximates in character to a fallacy.

By help of this brief review of the nature and causes of illusion, we
see that in general it may be spoken of as deviation of individual from
common experience. This applies to passive illusion in so far as it
follows from the accidents of individual experience, and it still more
obviously applies to active illusion as due to the vagaries of
individual feeling and constructive imagination. We might, perhaps,
characterize all illusion as partial view, partial both in the sense of
being incomplete, and in the other sense of being that to which the mind
by its peculiar predispositions inclines. This being so, we may very
roughly describe all illusion as abnormal. Just as hallucination, the
most signal instance of illusion, is distinctly on the border-land of
healthy and unhealthy mental life; just as dreams are in the direction
of such unhealthy mental action; so the lesser illusions of memory and
so on are abnormal in the sense that they imply a departure from a
common typical mode of intellectual action.

It is plain, indeed, that this is the position we have been, taking up
throughout our discussion of illusion. We have assumed that what is
common and normal is true, or answers to what is objectively real. Thus,
in dealing with errors of perception, we took for granted that the
common percept--meaning by this what is permanent in the individual and
the general experience--is at the same time the true percept. So in
discussing the illusions of memory we estimated objective time by the
judgment of the average man, free from individual bias, and apart from
special circumstances favourable to error. Similarly, in the case of
belief, true belief was held to be that which men in general, or in the
long run, or on the average, hold true, as distinguished from what the
individual under variable and accidental influences holds true. And even
in the case of introspection we found that true cognition resolved
itself into a consensus or agreement as to certain psychical facts.

_Criterion of Illusion._

Now, it behoves us here to examine this assumption, with the view of
seeing how far it is perfectly sound. For it may be that what is
commonly held true does not in all cases strictly answer to the real, in
which case our idea of illusion would have to be extended so as to
include certain common beliefs. This question was partly opened up at
the close of the last chapter. It will be found that the full
discussion of it carries us beyond the scientific point of view
altogether. For the present, however, let us see what can be said about
it from that standpoint of positive science to which we have hitherto
been keeping.

Now, if by common be meant what has been shared by all minds or the
majority of minds up to a particular time, a moment's inspection of the
process of correcting illusion will show that science assumes the
possibility of a common illusion. In the history of discovery, the first
assault on an error was the setting up of the individual against the
society. The men who first dared to say that the sun did not move round
the earth found to their cost what it was to fly in the face of a
common, though illusory, perception of the senses.[151]

If, however, by common be understood what is permanently and unshakably
held true by men in proportion as their minds become enlightened, then
science certainly does assume the truth of common perception and belief.
Thus, the progress of the physical sciences may be described as a
movement towards a new, higher, and more stable consensus of ideas and
beliefs. In point of fact, the truths accepted by men of science already
form a body of common belief for those who are supposed by all to have
the means of testing the value of their convictions. And the same
applies to the successive improvements in the conceptions of the moral
sciences, for example, history and psychology. Indeed, the very meaning
of science appears to be a body of common cognition to which all minds
converge in proportion to their capabilities and opportunities of
studying the particular subject-matter concerned.

Not only so, from a strictly scientific point of view it might seem
possible to prove that common cognition, as defined above, must in
general be true cognition. I refer here to the now familiar method of
the evolutionist.

According to this doctrine, which is a scientific method in so far as it
investigates the historical developments of mind or the order of mental
phenomena in time, cognition may be viewed as a part of the result of
the interaction of external agencies and the organism, as an incident of
the great process of adaptation, physical and psychical, of organism to
environment. In thus looking at cognition, the evolutionist is making
the assumption which all science makes, namely, that correct views are
correspondences between internal (mental) relations and external
(physical) relations, incorrect views disagreements between these
relations. From this point of view he may proceed to argue that the
intellectual processes must tend to conform to external facts. All
correspondence, he tells us, means fitness to external conditions and
practical efficiency, all want of correspondence practical incompetence.
Consequently, those individuals in whom the correspondence was more
complete and exact would have an advantage in the struggle for existence
and so tend to be preserved. In this way the process of natural
selection, by separately adjusting individual representations to
actualities, would make them converge towards a common meeting-point or
social standard of true cognition. That is to say, by eliminating or at
least greatly circumscribing the region of individual illusion, natural
selection would exclude the possibility of a persistent common illusion.

Not only so, the evolutionist may say that this coincidence between
common beliefs and true beliefs would be furthered by social as well as
individual competition. A community has an advantage in the struggle
with other communities when it is distinguished by the presence of the
conditions of effective co-operation, such as mutual confidence. Among
these conditions a body of true knowledge seems to be of the first
importance, since conjoint action always presupposes common beliefs,
and, to be effective action, implies that these beliefs are correct.
Consequently, it may be argued, the forces at work in the action of man
on man, of society on the individual, in the way of assimilating belief,
must tend, in the long run, to bring about a coincidence between
representations and facts. Thus, in another way, natural selection would
help to adjust our ideas to realities, and to exclude the possibility of
anything like a permanent common error.

Yet once more, according to Mr. Herbert Spencer, the tendency to
agreement between our ideas and the environment would be aided by what
he calls the direct process of adaptation. The exercise of a function
tends to the development of that function. Thus, our acts of perception
must become more exact by mere repetition. So, too, the representations
and concepts growing out of perceptions must tend to approximate to
external facts by the direct action of the environment on our physical
and psychical organism; for external relations which are permanent will,
in the long run, stamp themselves on our nervous and mental structure
more deeply and indelibly than relations which are variable and

It would seem, from all this, that so long as we are keeping to the
scientific point of view, that is to say, taking for granted that there
is something objectively real answering to our perceptions and
conceptions, the question of the possibility of a universal or
(permanently) common illusion does not arise. Yet a little more
reflection will show us that it may arise in a way. So far as the
logical sufficiency of the social consensus or common belief is accepted
as scientifically proved, it is open to suspicion on strictly scientific
grounds. The evolutionist's proof involves one or two assumptions which
are not exactly true.

In the first place, it is not strictly correct to say that all illusion
involves a practical unfitness to circumstances. At the close of our
investigation of particular groups of illusion, for example, those of
perception and memory, it was pointed out that many of the errors
reviewed were practically harmless, being either momentary and
evanescent, or of such a character as not to lead to injurious action.
And now, by glancing back over the field of illusion as a whole, we may
see the same thing. The day-dreams in which some people are apt to
indulge respecting the remote future have little effect on their
conduct. So, too, a man's general view of the world is often unrelated
to his daily habits of life. It seems to matter exceedingly little, in
general, whether a person take up the geocentric or the heliocentric
conception of the cosmic structure, or even whether he adopt an
optimistic or pessimistic view of life and its capabilities.

So inadequate, indeed, does the agency of natural selection seem to be
to eliminate illusion, that it may even be asked whether its tendency
may not be sometimes to harden and fix rather than to dissolve and
dissipate illusory ideas and beliefs. It will at once occur to the
reader that the illusion of self-esteem, discussed in the last chapter,
may have been highly useful as subserving individual self-preservation.
In a similar way, it has been suggested by Schopenhauer that the
illusion of the lover owes its force and historical persistence to its
paramount utility for the preservation of the species. And to pass from
a recurring individual to a permanently common belief, it is maintained
by the same pessimist and his followers that what they regard as the
illusion of optimism, namely, the idea that human life as a whole is
good, grows out of the individual's irrational love of life, which is
only the same instinctive impulse of self-preservation appearing as
conscious desire. Once more, it has been suggested that the belief in
free-will, even if illusory, would be preserved by the process of
evolution, owing to its paramount utility in certain stages of moral
development. All this seems to show at least the possibility of a kind
of illusion which would tend to perpetuate itself, and to appear as a
permanent common belief.

Now, so far as this is the case, so far as illusion is useful or only
harmless, natural selection cannot, it is plain, be counted on to weed
it out, keeping it within the narrow limits of the exceptional and
individual. Natural selection gets rid of what is harmful only, and is
indifferent to what is practically harmless.

It may, however, still be said that the process of direct adaptation
must tend to establish such a consensus of true belief. Now, I do not
wish for a moment to dispute that the growth of intelligence by the
continual exercise of its functions tends to such a consensus: this is
assumed to be the case by everybody. What I want to point out is that
there is no scientific proof of this position.

The correspondence of internal to external relations is obviously
limited by the modes of action of the environment on the organism,
consequently by the structure of the organism itself. Scientific men are
familiar with the idea that there may be forces in the environment which
are practically inoperative on the organism, there being no
corresponding mode of sensibility. And even if it be said that our
present knowledge of the material world, including the doctrine of the
conservation of energy, enables us to assert that there is no mode of
force wholly unknown to us, it can still be contended that the
environment may, for aught we know, be vastly more than the forces of
which, owing to the nature of our organism, we know it to be composed.
In short, since, on the evolution theory viewed as a scientific
doctrine, the real external world does not directly mirror itself in our
minds, but only indirectly brings our perceptions and representations
into adjustment by bringing into adjustment the nervous organism with
which they are somehow connected, it is plain that we cannot be certain
of adequately apprehending the external reality which is here assumed to

Science, then, cannot prove, but must assume the coincidence between
permanent common intuitions and objective reality. To raise the question
whether this coincidence is perfect or imperfect, whether all common
intuitions known to be persistent are true or whether there are any that
are illusory, is to pass beyond the scientific point of view to another,
namely, the philosophic. Thus, our study of illusion naturally carries
us on from scientific to philosophic reflection. Let me try to make this
still more clear.

_Transition to Philosophic View._

All science makes certain assumptions which it never examines. Thus, the
physicist assumes that when we experience a sensation we are acted on by
some pre-existing external object which is the cause, or at least one
condition, of the sensation. While resolving the secondary qualities of
light, sound, etc., into modes of motion, while representing the object
very differently from the unscientific mind, he agrees with this in
holding to the reality of something external, regarding this as
antecedent to and therefore as independent of the particular mind which
receives the sense-impression. Again, he assumes the uniformity of
nature, the universality of the causal relation, and so on.

Similarly, the modern psychologist, when confining himself within the
limits of positive science, and treating mind phenomenally or
empirically, or, in other words, tracing the order of mental states in
time and assigning their conditions, takes for granted much the same as
physical science does. Thus, as our foregoing analysis of perception
shows, he assumes that there is an external cause of our sensations,
that there are material bodies in space, which act on our sense-organs
and so serve as the condition of our sense-impressions. More than this,
he regards, in the way that has been illustrated in this work, the
percept itself, in so far as it is a process in time, as the normal
result of the action of such external agents on our nerve-structures, in
other words, as the effect of such action in the case of the healthy and
perfect nervous organism with the average organized dispositions,
physical and psychical; in which case he supposes the percept to
correspond, in certain respects at least, with the external cause as
made known by physical science. And, on the other hand, he looks on a
false or illusory percept as arising in another way not involving, as
its condition, the pre-existence of a corresponding material body or
physical agent. And in this view of perception, as of other mental
phenomena, the psychologist clearly takes for granted the principle that
all mental events conform to the law of causation. Further, he assumes
that the individual mind is somehow, in a way which it is not his
province to inquire into, one and the same throughout, and so on.

The doctrine of evolution, too, in so far as scientific--that is, aiming
at giving an account of the historical and pre-historical developments
of the collective mind in time--agrees with psychology in making like
assumptions. Thus, it conceives an external agency (the environment) as
the cause of our common sensations and perceptions. That is to say, it
represents the external world as somehow antecedent to, and so
apparently independent of, the perceptions which are adjusted to it. And
all this shows that science, while removed from vulgar unenlightened
opinion, takes sides with popular thought in assuming the truth of
certain fundamental ideas or so-called intuitive beliefs, into the exact
meaning of which it does not inquire.

When the meaning of these assumptions is investigated, we pass out of
the scientific into the philosophic domain. Philosophy has to critically
investigate the data of popular thought and of science. It has to
discover exactly what is implied in these fundamental principles. Then
it has to test their value by erecting a final criterion of truth, by
probing the structure of cognition to the bottom, and determining the
proper organ of certain or accurate knowledge; or, to put it another
way, it has to examine what is meant by reality, whether there is
anything real independently of the mind, and if so, what. In doing this
it inquires not only what common sense means by its object-world clothed
in its variegated garment of secondary qualities, its beauty, and so on,
but also what physical science means by its cosmic mechanism of sensible
and extra-sensible matter in motion: whether there is any kind of
objective reality belonging to the latter which does not also belong to
the former; and how the two worlds are related one to another. That is
to say, he asks whether the bodies in space assumed to exist by the
physicist as the antecedent conditions of particular sensations and
percepts are independent of mind and perception generally.[152]

In doing all this, philosophy is theoretically free to upset as much of
popular belief of the persistent kind as it likes. Nor can science find
fault with it so long as it keeps to its own sphere, and does not
directly contradict any truth which science, by the methods proper to
it, is able to establish. Thus, for example, if philosophy finds that
there is nothing real independently of mind, science will be satisfied
so long as it finds a meaning for its assumed entities, such as space,
external things, and physical causes.[153]

The student of philosophy need not be told that these imposing-looking
problems respecting cognition, making, up what the Germans call the
"Theory of Cognition," and the cognate problem respecting the nature of
reality, are still a long way from being settled. To-day, as in the days
of Plato and Aristotle, are argued, in slightly altered forms, the vexed
questions, What is true cognition? Is it a mere efflux from sensation,
a passive conformity of representation to sensation (sensualism or
empiricism)? or is it, on the other hand, a construction of active
thought, involving certain necessary forms of intelligence (rationalism
or intuitivism)?

Again, how are we to shape to ourselves real objective existence? Is it
something wholly independent of the mind (realism)? and if so, is this
known to be what we--meaning here common people and men of science
alike--represent it as being (natural realism), or something different
(transfigured realism)? Or is it, on the contrary, something involving
mind (idealism)? and if so, is it a strictly phenomenal distinction
within our conscious experience (empirical idealism, phenomenalism), or
one of the two poles of subject and object constituted by every act of
thought (rational idealism)? These are some of the questions in
philosophy which still await their final answer.

Philosophy being thus still a question and not a solution, we need not
here trouble ourselves about its problems further than to remark on
their close connection with our special subject, the study of illusion.

Our brief reference to some of the principal inquiries of philosophy
shows that it tends to throw doubt on things which the unreflecting
popular mind holds to be indubitable. Different schools of philosophy
have shown themselves unequally concerned about these so-called
intuitive certainties. In general it may be said that philosophy,
though, as I have remarked, theoretically free to set up its own
standard of certainty, has in practice endeavoured to give a meaning
to, and to find a justification for the assumptions or first principles
of science. On the other hand, it has not hesitated, when occasion
required, to make very light of the intuitive beliefs of the popular
mind as interpreted by itself. Thus, rationalists of the Platonic type
have not shrunk from pronouncing individual impressions and objects
illusory, an assertion which certainly seems to be opposed to the
assumptions of common sense, if not to those of science. On the other
hand, the modern empirical or association school is quite ready to
declare that the vulgar belief in an external world, so far as it
represents this as independent of mind,[154] is an illusion; that the
so-called necessary beliefs respecting identity, uniformity, causation,
etc., are not, strictly speaking, necessary; and so on. And in these
ways it certainly seems to come into conflict with popular convictions,
or intuitive certainties, as they present themselves to the unreflecting

Philosophy seems, then, to be a continuation of that process of
detecting illusion with which science in part concerns itself. Indeed,
it is evident that our special study has a very close connection with
the philosophic inquiry. What philosophy wants is something intuitively
certain as its starting-point, some _point d'appui_ for its
construction. The errors incident to the process of reasoning do not
greatly trouble it, since these can, in general, be guarded against by
the rules of logic. But error in the midst of what, on the face of it,
looks like intuitive knowledge naturally raises the question, Is there
any kind of absolutely certain cognition, any organ for the accurate
perception of truth? And this intimate relation between the scientific
and the philosophic consideration of illusion is abundantly illustrated
in the history of philosophy. The errors of sense, appearing in a region
which to the vulgar seems so indubitable, have again and again set men
thinking on the question, "What is the whole range of illusion? Is
perception, as popularly understood, after all, a big hallucination? Is
our life a dream?"[155]

On the other hand, if our study of the wide range of illusion is fitted
to induce that temper of mind which is said to be the beginning of
philosophy, that attitude of universal doubt expressed by Descartes in
his famous maxim, _De omnibus dubitandum_, a consideration of the
process of correction is fitted to lead the mind on to the determination
of the conditions of accurate knowledge. It is evident, indeed, that the
very conception of an illusion implies a criterion of certainty: to call
a thing illusory, is to judge it by reference to some accepted standard
of truth.

The mental processes involved in detecting, resisting, and overcoming
illusion, are a very interesting subject for the psychologist, though we
have not space here to investigate them fully. Turning to presentative,
and more particularly sense-illusions, we find that the detection of an
illusion takes place now by an appeal from one sense to another, for
example, from sight to touch, by way of verification;[156] now (as in
Myer's experiment) by a reference from sense and presentation altogether
to representation or remembered experience and a process of reasoning;
and now, (as in the illusions of art) conversely, by a transition of
mind from what is suggested to the actual sense-impression of the
moment. In the sphere of memory, again, illusion is determined, as such,
now by attending more carefully to the contents of memory, now by a
process of reasoning from some presentative cognition. Finally, errors
in our comprehensive general representations of things are known to be
such partly by reasoning from other conceptions, and partly by a
continual process of reduction of representation to presentation, the
general to the particular. I may add that the correction of illusion by
an act of reflection and reasoning, which brings the part into
consistent relation with the whole of experience, includes throughout
the comparison of the individual with the collective or social

We may, perhaps, roughly summarize these operations by saying that they
consist in the control of the lower automatic processes (association or
suggestion) by the higher activities of conscious will. This activity of
will takes the form now of an effort of attention to what is directly
present to the mind (sense-impression, internal feeling, mnemonic image,
etc.), now of conscious reflection, judgment, and reasoning, by which
the error is brought into relation to our experience as a whole,
individual and collective.

It is for the philosopher to investigate the inmost nature of these
operations as they exhibit themselves in our every-day individual
experience, and in the large intellectual movements of history. In no
better way can he arrive at what common sense and science regard as
certain cognition, at the kinds of knowledge on which they are wont to
rely most unhesitatingly.

There is one other relation of our subject to philosophic problems which
I have purposely left for final consideration. Our study has consisted
mainly in the psychological analysis of illusions supposed to be known
or capable of being known as such. Now, the modern association school
professes to be able to resolve some of the so-called intuitions of
common sense into elements exactly similar to those into which we have
here been resolving what are acknowledged by all as illusions. This fact
would seem to point to a close connection between the scientific study
of illusion and the particular view of these fundamental intuitions
taken by one philosophic school. In order to see whether there is really
this connection, we must reflect a little further on the nature of the
method which we have been pursuing.

I have already had occasion to rise the expression "scientific
psychology," or psychology as a positive science, and the meaning of
this expression must now be more carefully considered. As a positive
science, psychology is limited to the function of analyzing mental
states, and of tracing their origin in previous and more simple mental
states. It has, strictly speaking, nothing to do with the question of
the legitimacy or validity of any mental act.

Take a percept, for example. Psychology can trace its parentage in
sensation, the mode in which it has come by its contents in the laws of
association. But by common consent, a percept implies a presentative
apprehension of an object now present to sense. Is this valid or
illusory? This question psychology, as science, does not attempt to
answer. It would not, I conceive, answer it even if it were able to make
out that the whole mental content in the percept can be traced back to
elementary sensations and their combinations. For the fact that in the
chemistry of mind elements may combine in perfectly new forms does not
disprove that the forms thus arising, whether sentiments or
quasi-cognitions, are invalid. Much less can psychology dispute the
validity of a percept if it cannot be sure that the mind adds nothing to
sensation and its grouping; that in the genesis of the perceptive state,
with its intuition of something external and now present as object,
nothing like a form of intelligence is superimposed on the elements of
sensation, giving to the result of their coalescence the particular
unity which we find. Whether psychology as a positive science can ever
be sure of this: whether, that is to say, it can answer the question,
"How do we come by the idea of object?" without assuming some particular
philosophic or extra-scientific theory respecting the ultimate nature of
mind, is a point which I purposely leave open.

I would contend, then, that the psychologist, in tracing the genesis of
the percept out of previous mental experiences, no more settles the
question, What is the object of perception? than the physicist settles
it in referring the sense-impression (and so the percept) to a present
material agent as its condition.

The same applies to our idea of self. I may discover the concrete
experiences which supply the filling in of the idea, and yet not settle
the question, Does intelligence add anything in the construction of the
form of this idea? and still less settle the question whether there is
any real unity answering to the idea.

If this is a correct distinction, if psychology, as science, does not
determine questions of validity or objective meaning but only of
genesis, if it looks at mental states in relation only to their temporal
and causal concomitants and not to their objects, it must follow that
our preceding analysis of illusion involves no particular philosophic
theory as to the nature of intelligence, but, so far as accurate,
consists of scientific facts which all philosophic theories of
intelligence must alike be prepared to accept. And I have little doubt
that each of the two great opposed doctrines, the intuitive and the
associational, would claim to be in a position to take up these facts
into its particular theory, and to view them in its own way.

But in addition to this scientific psychology, there is another
so-called psychology, which is, strictly speaking, philosophic. This, I
need hardly say, is the association philosophy. It proceeds by analyzing
certain cognitions and sentiments into their elements, and straightway
declaring that they mean nothing more than these. That is to say, the
associationist passes from genesis to validity, from the history of a
conscious state to its objective meaning. Thus, from showing that an
intuitive belief, say that in causation, is not original (in the
individual or at least in the race), it goes on to assert that it is not
a valid immediate cognition at all. Now, I am not concerned here to
inquire into the logical value of this transition, but simply to point
out that it is extra-scientific and distinctly philosophic. If logically
justifiable, it is so because of some plainly _philosophic_ assumption,
as that made by Hume, namely, that all ideas not derived from
impressions are to this extent fictitious or illusory.

And now we are in a position to understand the bearing of our scientific
analysis of acknowledged illusions on the associationist's treatment of
the alleged illusions of common sense. There is no doubt, I think, that
some of the so-called intuitions of common sense have points of analogy
to acknowledged illusions. For example, the conviction in the act of
perception that something external to the mind and independent of it
exists, has a certain superficial resemblance to an hallucination of
sense; and moreover, the associationist seeks to explain it by means of
these very processes which underlie what is recognized by all as
sense-illusion.[158] Again, it may be said that our notions of force and
of a causal nexus in the physical world imply the idea of conscious
energy as known through our muscular sensations, and so have a
suspicious resemblance to those anthropomorphic illusions of which I
have spoken under Illusions of Insight. Once more, the consciousness of
freedom may, as I have suggested, be viewed as analogous in its form and
its mode of origin to illusions of introspection. As a last example, it
may be said that the mind's certain conviction of the innateness of some
of its ideas resembles those illusions of memory which arise through an
inability to think ourselves back into a remote past having a type of
consciousness widely unlike that of the present.

But now, mark the difference. In our scientific analysis of popularly
known illusions, we had something by which to determine the illusory
character of the presentation or belief. We had a popularly or
scientifically accepted standard of certainty, by a reference to which
we might test the particular _soi-disant_ cognition. But in the case of
these fundamental beliefs we have no such criterion, except we adopt
some particular philosophic theory, say that of the associationist
himself. Hence this similarity in structure and origin cannot in itself
be said to amount to a proof of equality of logical or objective value.
Here again it must be remarked that origin, does not carry validity or
invalidity with it.[159]

We thus come back to our starting-point. While there are close
relations, psychological and logical, between the scientific study of
the ascertained facts of illusion and the philosophic determination of
what is illusory in knowledge as a whole, the two domains must be
clearly distinguished. On purely scientific ground we cannot answer the
question, "How far does illusion extend?" The solution of this question
must be handed over to the philosopher, as one aspect of his problem of

One or two remarks may, perhaps, be hazarded in concluding this account
of the relation of the scientific to the philosophic problem of
illusion. Science, as we have seen, takes its stand on a stable
consensus, a body of commonly accepted belief. And this being so, it
would seem to follow, that so far as she is allowed to interest herself
in philosophic questions, she will naturally be disposed to ask, What
beliefs are shared in by all minds, so far as normal and developed? In
other words, she will be inclined to look at universality as the main
thing to be determined in the region of philosophic inquiry. The
metaphysical sceptic, fond of daring exploits, may break up as many
accepted ideas as he likes into illusory _débris_, provided only he has
some bit of reality left to take his stand on. Meanwhile, the scientific
mind, here agreeing with the practical mind, will ask, "Will the beliefs
thus said to be capable of being shown to be illusory ever cease to
exercise their hold on men's minds, including that of the iconoclast
himself? Is the mode of demonstration of such a kind as to be likely
ever to materially weaken the common-sense 'intuition'?"

This question would seem to be most directly answerable by an appeal to
individual testimony. Viewed in this light, it is a question for the
present, for some few already allege that in their case philosophic
reasonings exercise an appreciable effect on these beliefs. And so far
as this is so, the man of scientific temper will feel that there is a
question for him.

It is evident, however, that the question of the persistence of these
fundamental beliefs is much more one for the future than for the
present. The correction of a clearly detected illusion is, as I have
more than once remarked, a slow process. An illusion such as the
apparent movement of the sun will persist as a partially developed error
long after it has been convicted. And it may be that the fundamental
beliefs here referred to, even if presumably illusory, are destined to
exercise their spell for long ages yet.

Whether this will be the case or not, whether these intuitive beliefs
are destined slowly to decay and be dissolved as time rolls on, or
whether they will retain an eternal youth, is a question which we of
to-day seem, on a first view of the matter, to have no way of answering
which does not assume the very point in question--the truth or falsity
of the belief. This much may, however, be said. The associationist who
resolves these erroneous intuitions into the play of association, admits
that the forces at work generating and consolidating the illusory belief
are constant and permanent forces, and such as are not likely to be less
effective in the future than they have been in the past. Thus, he
teaches that the intuition of the single object in the act of perception
owes its strength to "inseparable association," according to which law
the ideas of the separate "possibilities of sensation," which are all we
know of the object, coalesce in the shape of an idea of a single uniting
substance. He adds, perhaps, that heredity has tended, and will still
tend, to fix the habit of thus transforming an actual multiplicity into
an imaginary unity. And in thus arguing, he is allowing that the
illusion is one which, to say the least of it, it will always be
exceedingly difficult for reason to dislodge.

In view of this uncertainty, and of the possibility, if not the
probability, of these beliefs remaining as they have remained, at least
approximately universal, the man of science will probably be disposed to
hold himself indifferently to the question. He will be inclined to say,
"What does it matter whether you call such an apparently permanent
belief the correlative of a reality or an illusion? Does it make any
practical difference whether a universal 'intuition,' of which we cannot
rid ourselves, be described as a uniformly recurring fiction of the
imagination, or an integral constitutive factor of intelligence? And, in
considering the historical aspect of the question, does it not come to
much the same thing whether such permanent mental products be spoken of
as the attenuated forms or ghostly survivals of more substantial
primitive illusions (for example, anthropomorphic representations of
material objects, 'animistic' representations of mind and personality),
or as the slowly perfected results of intellectual evolution?"

This attitude of the scientific mind towards philosophic problems will
be confirmed when it is seen that those who seek to resolve stable
common convictions into illusions are forced, by their very mode of
demonstration, to allow these intuitions a measure of validity. Thus,
the ideas of the unity and externality attributed to the object in the
act of perception are said by the associationist to answer to a matter
of fact, namely, the permanent coexistence of certain possibilities of
sensation, and the dependence of the single sensations of the individual
on the presence of the most permanent of these possibilities, namely,
those of the active or muscular and passive sensations of touch, which
are, moreover, by far the most constant for all minds. Similarly, the
idea of a necessary connection between cause and effect, even if
illusory in so far as it expresses an _objective_ necessity, is allowed
to be true as an expression of that uniformity of our experience which
all scientific progress tends to illustrate more and more distinctly.
And even the idea of a permanent self, as distinct from particular
fugitive feelings, is admitted by the associationist to be correct in so
far as it expresses the fact that mind is "a series of feelings which
is aware of itself as past and future." In short, these "illusory
intuitions," by the showing of those who affirm them to be illusory, are
by no means hallucinations having no real object as their correlative,
but merely illusions in the narrow sense, and illusions, moreover, in
which the ratio of truth to error seems to be a large one.

It would thus appear that philosophy tends, after all, to unsettle what
appear to be permanent convictions of the common mind and the
presuppositions of science much less than is sometimes imagined. Our
intuitions of external realities, our indestructible belief in the
uniformity of nature, in the nexus of cause and effect, and so on, are,
by the admission of all philosophers, at least partially and
_relatively_ true; that is to say, true in relation to certain features
of our common experience. At the worst, they can only be called illusory
as slightly misrepresenting the exact results of this experience. And
even so, the misrepresentation must, by the very nature of the case, be
practically insignificant. And so in full view of the subtleties of
philosophic speculation, the man of science may still feel justified in
regarding his standard of truth, a stable consensus of belief, as above

|Transcribers note: In the original some footnotes read 'note[1]'and    |
|'note[2]'. They have been renumbered to allow readers to refer directly|
|to the correct footnote.                                               |



  Abercrombie, Dr. J, 141, note[82], 278.

  Abnormal life, relation of,
    to normal, 1, 120, 121, 124, 182, 277, 284, note[132], 336;
    effects of amputation, 62;
    modification of sensibility in, 65;
    gross sense-illusions of, 111, hallucinations of, 118;
    sense of personal identity in, 289.

  Active, stage in perception, 27;
    illusion distinguished from passive, 45, 332-334.

  Actor. _See_ Theatre.

  Adaptation, illusion as want of, 124, 188, 339.

  Æsthetic intuition, 213;
    illusions of, 214.

  After-dreams, 144, 183.

  After-sensation, after-impression, 55, 115.

  Anæsthesia, 65.

  Ancestral experience, results of, 281.

  Animals, recognition of portraits by, 105;
    expectation of, 298.

  Anthropomorphism, 225, 360.

  Anticipation. _See_ Expectation.

  Apparitions. _See_ Hallucination.

  Aristotle, 130.

  Art, illusions of, 77, 104.

  Artemidoros, 129.

  Association, laws of, in perception, 22;
    in dreams, 153, 156;
    link of resemblance in dreams, 159;
    associative dispositions in dreams, 169;
    effect of, in insight, 221;
    inseparable, 359.

  Associationist, views of, 349, 352, 355.

  Attention, involved in perception 21;
    absence of, in sense-illusion, 39, 87;
    relation of, to recognition of objects, 90;
    expectant, 93;
    attitude of, in dreaming, 137, 172;
    to internal mental states, 194;
    absence of, in errors of insight, 228.

  Authority, influence of, in introspection, 210;
    in belief, 325.

  Autobiography, errors connected with, 276, 280.

  Automatic activity of centres, in hallucinations, 113;
    in dreams, 136, 151;
    automatic intellectual processes, 300, 335, 352.


  Baillarger, J., 13, note[1], 113, note[57], 119,
    notes[64] and [65], 120, note[66].

  Bain, Dr. A., 32, note[12], 117, note[60], 190.

  Beattie, J., 141, note[82].

  Beauty, sentiment of, 206, 213.

  Belief, immediate, 14, 15, 294;
    simple and compound, 296;
    illusory forms of, 297;
    simple expectation, 297;
    expectation, of extra-personal experiences, 307;
    retrospective, 309;
    in persistent objects and persons, 312;
    self-esteem, 315;
    representation of classes of things, 322;
    representations of mankind, 322;
    representation of life and the world as a whole, 322;
    as predisposition to error, 324;
    amount of divergence in, 325;
    tendency towards convergence in, 326.

  Beneficial, correct knowledge as, 340;
    illusion as, 342.

  Berkeley, Bishop, 218, 349, note[154].

  Binet, A., 53, note[20].

  Boismont, Brierre de, 11, note[1].

  Börner, J., 146.

  Braid, James, 186, 187.

  Brewster, Sir D., 42, 73, 81, 116.

  Brücke, E., 77, note[38].

  Byron, Lord, 116.


  Carpenter, Dr. W.B., 32, note[12], 108, 110, note[56], 186, 231,
    note[111], 265, note[125], 276.

  Castle-building, as illusory perception, 3, 99.

  Cause, idea of, in science, 344;
    reality of relation of, 347, 349, 356, 360.

  Change, a condition of conscious life, 252, 287, note[133].

  Childhood, our recollections of, 263, 269.

  Children, curiosity of, 175, 180;
    estimate of time by, 256;
    confusion of dream and waking life by, 276;
    imagination of, 279;
    self-assertion of, 319;
    intellectual condition of, 357, note[159].

  Clarke, Dr. E.H., 117.

  Classification, in recognition of sensation, 21;
    in recognition, of object, 24;
    in introspective recognition, 193.

  Clifford, Professor W.K., 56, note[24].

  Coalescence, of sensations, 43, 52;
    of dream-images, 162;
    of internal feelings, 196;
    of mnemonic images, 265.

  Coenæsthesis, 41, 99, 145, 286, 288.

  Cognition, immediate or intuitive, 5, 14-16, 294;
    presentative and representative, 9, 13, 217, 330;
    nature of, in dreams, 168, 172;
    nature of, generally, 295, 331;
    philosophic problems of, 346.

  Colour, external reality of, 8, 37;
    illusory perception of, 37, 88;
    subjective complementary colours (colour-contrast), 67, 83.

  Coloured media, objects seen through, 82.

  Common cognition, and truth, 337;
    genesis and validity of, 353.

  Common experience distinguished from
    individual, 26, 27, 137, 209, 214, 336, 351;
    illusion as, 47,325, 337.

  Common sense, intuitions of, 346, 349, 352, 357.

  Complementary colours, 67, 83.

  Concave, apparent conversion of, into convex, 84.

  Conjuror, tricks of, 56, 106.

  Consciousness, veracity of, 192, 205;
    inspection of phenomena of, 196;
    of self, 283, 285.

  Consensus, the standard of truth, 7, 8, 211, 325, 338, 357.

  Conservation of energy, 343.

  Construction, rational, in dreams, 170.

  Continuum, the perception of the world as, 52, 56, note[24].

  Correction of illusion, in sense-illusion, 38, 124, 137;
    dreams, 182;
    introspection, 210;
    insight, 229;
    memory, 291;
    historical correction 338;
    intellectual processes involved in, 351.

  Criterion of illusion, 337.

  Cudworth, R., 161


  Deception of the senses, 19;
    self-deception, 200;
    conscious deception of others, 222.

  Delboeuf, J., 175, note[97], 235, note[113].

  _Delirium tremens_, 118, note[62].

  Democritus, 130.

  De Quincey, 253, 280.

  Descartes, R., 116, 350.

  Dickens, Charles, 277.

  Direction, illusory sense of, in vision, 66, 71, 73;
   in hearing, 72, 75.

  Disease. _See_ Abnormal life.

  Dissolution. _See_ Evolution.

  Doubt, starting-point in philosophy, 350.

  Dreams, relation of, to illusions of sense, 18, 130;
    and waking experience, 127;
    theories of, 128;
    physiology of, 131;
    extent of, in sleep, 132;
    psychological conditions of, 136;
    excitants of, 139, 143;
    exaggeration in, 147;
    symbolism of, 149;
    as results of automatic activity of centres, 151;
    as results of association, 153;
    structure of, 156;
    incoherent, 156;
    coherent, 161;
    action of feeling in, 164;
    play of associative dispositions in, 168;
    co-operation of attention and intelligence in, 172;
    limits of intelligence in, 180;
    after-dreams, 183, 274;
    relation of, to hypnotic condition, 185;
    experience of, in relation to errors of memory, 273.


  Eccentricity, law of, 59.

  Ego. _See_ Self.

  Emotion, and illusion of perception, 103;
    and hallucination, 115;
    and bodily sensations, 150;
    control of dreams by, 164;
    introspection of, 199;
    and illusion of introspection, 203;
    and æsthetic intuition, 213;
    and illusion of memory, 270;
    and illusion of belief, 306, 324;
    and cognition generally, 357, note[159].

  Empiricism, philosophic, 348.

  _Ennui_, and sense of time, 250.

  Environment, sources of sense-illusion in, 47, 48, 70;
    view of, in mental disease, 290, 326;
    view of, in normal life, 323;
    action of, in assimilating belief, 339.

  Error, immediate and mediate, 6, 334.

  Esquirol, J.E.D., 12, note[2].

  Evolution, relation of, to dissolution, 122;
    of power of introspection, 209;
    of power of insight, 230;
    and self-assertion, 320;
    evolutionist's view of error, 339;
    doctrine of, as science, 346.

  Exaggeration, in interpretation of sensations, 65;
    in dream-interpretation, 147;
    in memory, 269.

  Expectation, preliminary to perception, 30;
    and illusory perception, 93, 102, 106;
    nature of, 295;
    and memory, 298;
    of new experience, 301;
    of remote events, 302;
    measurement of duration in, 302;
    action of imagination in, 305;
    extension of meaning of, 307, 308.

  Experience, effect of, in perception, 22, 68, 85, 86, 91;
    external and internal, 194, 210;
    revivals of waking, in dreams, 152;
    effects of present, on retrospection, 267;
    anticipation of new, 301.

  External world. _See_ World.


  Fallacy and illusion 6, 335;
    of testimony, 265.

  Familiarity, sense of, in new objects, 272, 281.

  Fechner, G.T., 51.

  Ferrier, Dr., 32, note[12], 58, note[26].

  Fiction, as producing illusion, 278, 279, 311.

  Fitness. _See_ Adaptation.

  Flattery, _rationale_ of, 200, 222.

  Forgetfulness and illusion, 278, 279, 311.

  Free-will, doctrine of, 207, 342, 356.

  Future. _See_ Expectation.


  Galton, F., 117.

  Ghosts. _See_ Hallucination.

  Goethe, 116, 117, 280 and note[131].

  Griesinger, W., 13, note[2], 63, note[31], 66, note[32], 115, 118,
    note[62], 119, note[64], 120, note[66], 290, note[135], 327,

  Gruithuisen, 143, 144.

  Gurney, E., 224, note[109].


  Hall, G.S., 186, note[102].

  Hallucination, and illusion, 11, 109, 111, 112, 121;
    and subjective sensation, 63, 109, 121;
    sensory and motor, 66;
    nervous conditions of, 112-114;
    incomplete and complete, 113;
    as having either central or peripheral origin, 113;
    causes of, classified, 115;
    in sane condition, 116;
    in insanity, 118;
    visual and auditory, 119;
    dreams regarded as, 139, 151;
    hypnagogic, 143;
    after-dreams and ghosts, 183;
    of memory, 271;
    relation of, to errors of belief, 322;
    intuition of external world regarded as, 355.

  Happiness, feeling of, 200.

  Harmful, illusion as, 188, 229, 292, 339.

  Harmless, illusions as, 124, 292, 341.

  Hartley, D., 139, 256, note[124], 279.

  Hearing, as mode of perception, 34, 48;
    localization of impression in, 60;
    sense of direction in, 72;
    activity of, in sleep, 140;
    and muscular sense, 171.

  Heidenhain, Dr., 186-188.

  Helmholtz, H., 22, 23, note[7], 44, 51, 54 and note[22], 55, note[23],
    57, 67, note[33], 78, note[39], 80, 85, note[43], 88, 90, 207,

  Heraclitus, 137.

  Heredity, and illusion of memory, 280;
    action of, in perpetuating intuition, 359.

  Hering, E., 67, note[33].

  Hodgson, Shadworth H., 347, note[153].

  Holland, Sir H., 277.

  Hood, Thomas, 146.

  Hope, illusory. _See_ Expectation.

  Hoppe, Dr. J.I., 51, 58, note[26].

  Horwicz, A., 145, note[85].

  Hume, D., 355.

  Huxley, Professor T., 119, note[1].

  Hyperæsthesia, 65.

  Hypnotism, 185.

  Hypochondria, 65.

  Hypothesis, as illusory, 310, 311.


  Idealism, 348.

  Identity, cases of mistaken, 267.

  Identity, personal, confusion of, in dreams, 163;
    consciousness of, 241, 267, 282, 285;
    illusory forms of, 283;
    gross disturbances of, in normal life, 287;
    in abnormal life, 289;
    momentary confusions of, 293.

  Illusion, definition of, 1;
    varieties of, 9;
    extent of, 328;
    _rationale_ of, 331, 337.

  Image (physical). _See_ Reflection.

  Image (mental), in perception, 22;
    seat of, 32;
    in dreams, 138;
    mnemonic, 236.

  Imagination, play of, in perception, 95, 99;
    and sense-illusion, 106;
    nature of, in dreaming, 136, 161;
    as antecedent of dream, 152, 158;
    as poetic interpretation of nature, 224;
    memory corrupted by effect of past, 264, 273, 277;
    present, creating the semblance of recollection, 267, 271;
    play of, in expectation, 305;
    as element of illusion generally, 333.

  Immediate. _See_ Cognition.

  Individual, and common experience, 26, 27, 137, 209, 214, 336;
    dream-experience as, 44, 68;
    internal experience as, 209;
    memory as, 232;
    belief and truth, 338.

  Inference, and immediate knowledge, 6, 334;
    in perception, 22, 26, 68;
    in belief, 295.

  Innate, recollection as, 280;
    principles, 295, 356.

  Insane, sense-illusions of, 63, 65, 111;
    hallucinations of, 118;
    dreaming and state of, 182;
    mnemonic illusions of, 278, 289;
    beliefs of, 327.

  Insight, nature of, 217;
    illusions of, defined, 220;
    passive illusions of, 220;
    histrionic illusion, 222;
    active illusions of, 223;
    poetic interpretation of nature, 224;
    value of faculty of, 228.

  Interpretation, in correct perception, 22;
    of impression and experience, 70;
    and volition, 95;
    and fixed habits of mind, 101;
    and temporary attitude of mind, 102;
    of sensations in dreams, 137, 147;
    of internal feelings, 203;
    of others' feelings, 217;
    of nature by poet, 225;
    recollection as, 242.

  Introspection, nature of, 14, 189;
    illusory forms of, 190;
    confusion of inner and outer experiences, 194;
    inaccurate inspection of feelings, 196;
    presentation and representation confused, 199;
    feelings and inferences from these, 203;
    moral self-scrutiny, 204;
    philosophic, 205;
    value of, 208.

  Intuition. _See_ Cognition.

  Intuitivism, 348.


  Jackson, Dr. J. Hughlings, 27, note[9], 33, 123, note[67].

  Johnson, Dr., 116.


  _Klang_, as compound sensation, 53.

  Knowledge. _See_ Cognition.


  Language, function of, 195.

  Leibnitz, 133.

  Lélut, L.F., 120, note[66].

  Lessing, G. E., 133, note[73].

  Leuret, 290, note[135].

  Lewes, G.H., 28, 32, note[12], 52, note[30], 62, note[1], 68,
    note[35], 89, note[45], 115, note[58], 150.

  Life, our estimate of, 323, 326, 327.

  Light, sensation and perception of, 59;
    effects of reflection and refraction, of, 73;
    representation, of, in painting, 88, 91;
    action of, in sleep, 140.

  Localization, as local discrimination of sensations, 52;
    as localizing of sensations, 59, 60;
    illusory, 61, 82;
    in hallucination, 118, 119;
    in dreaming, 148;
    of events in time, in memory, 238, 245;
    in expectation, 304.

  Locke, 133, note[73].

  Lotze, H., 60, note[29].

  Lover, illusion of, 224, 227, 342.

  Luminosity of painting, 88, 91.

  Lustre, as compound sensation, 54.

  Lyell, Sir Charles, 311.


  Magic, arts of, 73.

  Magnitude, apparent, in vision, 75, note[37];
    perception of, in pictorial art, 88, 91;
    of time-intervals, 245, 249;
    recollection of, 268.

  Malebranche, 116.

  Mankind, our views of, 322.

  Matter. _See_ World (material).

  Maudsley, Dr. H., 32, note[12].

  Maury, A., 140, 143, 153, note[92], 159, 163, note[94], 173.

  Mayer, Dr. A., 66, note[32].

  Measurement, subjective, of time, 245.

  Media, coloured, illusions connected with presence of, 82.

  Memory, nature of, 9, 13, 231;
    veracity of, 232, 290;
    defined, 234;
    psychology of, 236;
    physiology of, 237;
    localization of events in, 238;
    and sense of personal identity, 241, 283;
    illusions of, 241;
    illusory localization, 245, 256;
    distortions of, 261;
    hallucinations of, 271;
    illusions respecting personal identity, 283;
    relation of, to belief, 295;
    compared with expectation, 297;
    and inference, 335.

  Metempsychosis, 294.

  Meyer, H., 83, 144.

  Mill, J.S., 298, note[138], 309.

  Mirrors, as means of delusion, 73.

  Misanthropist, 2, 323.

  Mitchell, Dr. Weir, 62.

  Monomania, 111.

  Moral, intuition, 216;
    self-inspection, 204.

  Motor illusions. _See_ Muscular sense.

  Movement, apparent, 50, 57, 73, 81, 95, 107;
    in dreams, 142, 154.

  Müller, Johannes, 58, note[27], 100, 117, 143.

  _Muscæ volitantes_, 118, note[62].

  Muscular sense, in perception, 23;
    illusions connected with, 50, 57, 62, 66;
    co-operation, of, in dreams, 142, 154.

  Music, subjective interpretation of, 223.


  Natural selection, effect of, in eliminating error, 340.

  Nature, personification of, 224;
    uniformity of, 344, 360.

  Necessity, idea of, 349, 360.

  Nervous system, and conditions of perception, 31;
    connections of, 32, 169;
    function of, and force of stimulus, 47, 50;
    prolonged activity of, 55;
    specific energy of, 58;
    variations in state of, 64;
    fatigue of, 65, 115;
    disease of, _ibid._;
    nervous conditions of hallucination, 112, 115;
    nervous dissolution and evolution, 122;
    condition of, in sleep, 131;
    in hypnotic condition, 186;
    nervous conditions of memory, 237;
    nervous conditions of illusion in general, 334.

  Normal life, relation of,
    to abnormal, 1, 121, 124, 182, 277, 284, note[132];
    hallucinations of, 116.


  Object, nature of, 36, 353.

  Objective and subjective experience, 26, 27, 137, 214.

  Old age, dreams how regarded in, 276.

  Oneirocritics, 129.

  Opera, illusion connected with, 104.

  Optimism, 323, 327, 342.

  Organic sensations, discrimination of, 41;
    interpretation of, 99;
    in sleep, 145, 148.

  Organism, conditions of illusion in, 47, 50;
    relation of our conception of the universe to sensibilities of, 343.

  Orientation, 125, 138.


  Pain, recollection of, 264, 270.

  Painting, representation of third dimension by, 77;
    apparent movement of eye in portrait, 81;
    discrepancies between, and object in magnitude and luminosity, 88;
    realization of, and mental preparation, 105;
    realization of, by animals, 105.

  Paræsthesia, 68.

  Paralysis of ocular muscles, 66.

  Passive, and active factor in perception, 27;
    and active illusion, 45.

  Percept, 22;
    and sense-impression, 59.

  Perception, a form of immediate knowledge, 10, 13, 17, 18;
    external and internal, 14;
    philosophy of, 14, 20, 22, 36, 346, 348, 353, 355, 359;
    illusions of, 19, 35;
    psychology of, 20;
    and inference, 22, 26, 76;
    physiological conditions of, 31.

  Persistent objects, representation of, 312.

  Persistent self. _See_ Personal identity.

  Personal equation, in perception, 101;
    in æsthetic intuition, 214;
    in memory, 292;
    in belief, 324.

  Personal identity, consciousness of, 241, 282, 285;
    illusions connected with, 283;
    disturbances in sense of, 287;
    sense of, in insanity, 289;
    momentary confusions of, 293;
    philosophic problem of, 285, 354, 360.

  Personification of nature, 224.

  Perspective, linear, 79, 97, 98;
    aerial, 80;
    of memory, 245.

  Pessimism, 323, 327.

  Phenomenalism, 348.

  Philosophy, conception of illusion by, 7, 36, 205, 285, 349;
    of mind, 132, 285, 344, 348;
    as theory of knowledge, 295, 346;
    and science, 346, 348;
    and common sense, 347, 349;
    problems of, 347.

  Phosphenes, 58.

  Physical science. _See_ Science.

  Plato, 281.

  Platonists, 349.

  Pleasure, feeling of, 200;
    recollection of, 264, 270.

  Plutarch, 133, note[73].

  Poetry, lyrical and dreams, 164;
    misinterpretation of, 223;
    personification, 224.

  Points, discrimination of, 52.

  Poisons, action of, 115.

  Pollock, F., 184, note[101].

  Pollock, W.H., 184.

  Predisposition, action of, in perception, 44, 101, 102;
    in æsthetic intuition, 215;
    in insight, 223;
    in recollection, 268;
    in belief, 305, 319;
    belief as, 324.

  Prejudice. _See_ Predisposition.

  Prenatal experience, recollection of, 281.

  Preperception, 27;
    illusions connected with, 44, 93;
    voluntary, 95;
    result of habit of mind, 101;
    result of temporary conditions, 102;
    as sub-expectation, 102;
    as definite expectation, 106.

  Presentation and representation, 9, 10, 13, 14, 192, 234, 329, 330.

  Projection, outward, of sensations, 63;
    of mental image, 111, 112;
    of solid form on flat, 79, 81, 96.

  Prophetic, dreams as, 129, 147, note[88];
    enthusiast, 307.

  Psychology, popular and scientific, 9, 10;
    distinguished from philosophy, 14, 36, 345, 352;
    introspective method of, 208;
    as a kind of philosophy, 305.

  Public events, localization, of, by memory, 258.


  Radestock, P., 130, note[71], 132, note[72], 134, note[75], 140, 141,
    149, note[90], 162, 182, 275.

  Rationalism, philosophic, 348.

  Realism, 348.

  Reality, nature of, 36, 346.

  Recognition, and perception, 24, 25;
    illusions of, 87;
    and memory, 234.

  Reflection (of light), illusions connected with, 73, 83.

  Refraction and optical illusion, 73.

  Relative, sensation as, 64;
    attention to magnitude and brightness as, 91;
    estimate of duration as, 249.

  Relief, illusory perception of, 75, 96.

  Representation and presentation, 9, 10, 13, 14, 192.

  Retrospection. _See_ Memory.

  Ribot, T., 238, note[114], 290, note[135].

  Richter, J.P., 143.

  Robertson, Professor G.C., 35, note[14].

  Romanes, G.J., 105, note[2], 250, note[122].

  Rousseau, 280.


  Savage, dream theory of, 128;
    idea of nature of, 225.

  Scherner, C.A., 140, 149.

  Schopenhauer, A., 145, 342.

  Schroeder, H., 85.

  Science, philosophy and, 8, 36, 285, 344;
    conception of the material world in physical, 36, 343, 346, 347;
    and common cognition, 338, 357.

  Scott, Sir W., 116, 125.

  Secondary qualities, 36, 344.

  Selection, process of, in perception, 95;
    in dreams, 174;
    in memory, 257, 263.

  Self, confusion of, in dreams, 163;
    introspective knowledge of, 192;
    self-deception, 200;
    identity of, 241, 282, 285;
    confusion of present and past, 267, 284;
    disturbances in recognition of, 287, 289;
    momentary confusions of, 295;
    confusion of present and future, 305.

  Self-esteem, illusion of, 315;
    origin of, 319;
    utility of, 342.

  Self-preservation, 320.

  Sensation, element in perception, 20;
    discrimination and classification of, 21;
    interpretation of, 22;
    inattention to, 39, 87;
    modified by central reaction, 39, 87, 89, 91;
    confusion of novel, 40;
    indistinct, 41;
    misinterpretation of, 44;
    relation of, to stimulus, 46, 50;
    limits to discrimination of, 52;
    after-impression, 55;
    subjective, 59, 62, 107, 143;
    localization of, 59.

  Sensibility, limits of, 50;
    variations of, 64.

  Sensualism, philosophic, 348.

  Shadow, cast, 77.

  Shakespeare, 3.

  Sight, mode of perception, 19, 33, 34, 48, 49;
    local discrimination in, 52;
    single vision, 54;
    localization of impression in, 60;
    in sleep, 139;
    images of, in sleep, 150, 154.

  Single, vision, 54;
    touch, 72.

  Sleep, mystery of, 127;
    physiology of, 131.

  Sleight of hand. _See_ Conjuror.

  Smell, as mode of perception, 34, note[14];
    localization of impression in, 60;
    subjective sensations of, 108;
    in sleep, 141;
    and taste, 171.

  Solidity, illusory perception of, 75, 96.

  Space, representation of, 207.

  Specific energy of nerves, 58.

  Spectra, ocular, etc. _See_ Subjective sensation.

  Spencer, Herbert, 32, note[12], 128, note[69], 323, 340.

  Spinoza, 143, 184.

  Spiritualist _séances_, 103, 107, 123, 265.

  Stereoscope, 75.

  Stewart, Dugald, 172, 306.

  Stimulus, qualitative relation of, to sensations, 46, 58, 67;
    quantitative relation of, to sensation, 50, 64;
    after-effect of, 55;
    prolonged action of, 56;
    subjective or internal, 62;
    exceptional relation of, to organ, 70;
    action of, in sleep, 135, 139, 143;
    in hypnotic condition, 186.

  Strümpell, L., 144, 147, note[89].

  Subjective, experience, 26, 27, 137, 214;
    movement, 51, 57;
    sensation, 59, 62, 107, 113, 121, 143.

  Suggestion, by external circumstances, 30, 44, 89, 91, 267;
    verbal, 30, 106, 188, 215, 268, 301, 310.

  Symbol, dream as, 129, 149.

  Sympathy, basis of knowledge, 223;
    and illusion of insight, 223;
    and illusion of memory, 277;
    and momentary illusion, 293.


  Taine, H., 60, note[29], 108, note[54], 117, note[59], 137,
    298, note[137], 356, note[158].

  Taste, æsthetic. _See_ Æsthetic intuition.

  Taste, localization of impression in, 60;
    subjective sensations of, 63;
    variations in sensibility, 68;
    activity of, in sleep, 141;
    and smell, 171.

  Temperament, a factor in sense-illusion, 101;
    in dreams, 137;
    in illusory belief, 325;
    in illusion generally, 334, note[149].

  Temperature, sense of, 65.

  Tennyson, A., 226.

  Testa, A.J., 131.

  Testimony, of consciousness, 205;
    fallacies of, 265;
    to identity, 267.

  Thaumatrope, 56.

  Theatre, illusion of the, 104, 222;
    self-deception of the actor, 200.

  Thompson, Professor S.P., 51, note[17].

  Thought, in relation to belief, 326.

  Time, retrospective idea of, 239, 246, 250;
    constant error in estimate of, 245;
    subjective estimate of, 249;
    contemporaneous estimate of, 250;
    sense of, in insanity, 290;
    prospective estimate of, 303.

  Touch, as form of perception, 33, 34, 49;
    local discrimination in, 52;
    subjective sensations of, 62;
    variations in sensibility of, 65;
    in sleep, 141.

  Transformation, in perception, 94;
    of images in dreams, 163;
    in memory, 262, 267;
    in expectation, 305.

  Trick. _See_ Conjuror.

  Tuke, Dr., 110.

  Tylor, E.B., 128, note[69].


  Unconscious, inference, 22, 68, 269, 335, note[150];
    mental activity, 133, 235;
    impressions, 41, 152.

  Useful. _See_ Beneficial.


  Vanity. _See_ Self-esteem.

  Venn, J., 299, note[139].

  Ventriloquism, 82.

  Verification, of sense-impression, 38, 351;
    of self-inspection, 210;
    of memory, 291.

  Verisimilitude, in art, 80, 88;
    in theatrical representation, 104;
    in dreams, 168.

  Vierordt, 245.

  Vision. _See_ Sight.

  Visions, 1, 110;
    dreams regarded as, 128, 131.

  Vital sense. _See_ Coenæsthesis.

  Voice, internal, 119, 194;
    activity of, in dreams, 155.

  Volition, and perception, 95;
    absence of, during sleep, 137,172;
    co-operation of, in correction, of illusion, 352.

  Volkelt, J., 172.


  Weber, E.H., 43.

  Weinhold, Professor, 186.

  Wetness, perception of, 53.

  Wheatstone, Sir C, 75.

  Wheel of life, 56.

  Will. _See_ Volition.

  Wordsworth, W., 281.

  World, our estimate of, 323, 326, 327;
    scientific conception of material, 8, 36, 343, 344;
    reality of external, 344-346, 349, 353, 355, 360.

  Wundt, Professor, W. 13, note[2], 31, note[11], 32, note[12], 58,
    note[27], 67, note[34], 75, 93, note[47], 118, note[63], 136,
    note[77], 139, 143, 177, 246, 247, note[119], 251, 252, 254.



[1] A history of the distinction is given by Brierre de Boismont, in his
work _On Illusions_ (translated by R. T. Hulme, 1859). He says that
Arnold (1806) first defined hallucination, and distinguished it from
illusion. Esquirol, in his work, _Des Maladies Mentales_ (1838), may be
said to have fixed the distinction. (See Hunt's translation, 1845, p.

[2] This fact has been fully recognized by writers on the pathology of
the subject; for example, Griesinger, _Mental Pathology and
Therapeutics_ (London, 1867), p. 84; Baillarger, article, "Des
Hallucinations," in the _Mémoires de l'Académie Royale de Médecine_,
tom. xii. p. 273, etc; Wundt, _Physiologische Psychologie_, p. 653.

[3] I here touch on the distinction between the psychological and the
philosophical view of perception, to be brought out more fully

[4] It might even be urged that the order here adopted is scientifically
the best, since sense-perception is the earliest form of knowledge,
introspected facts being known only in relation to perceived facts. But
if the mind's knowledge of its own states is thus later in time, it is
earlier in the logical order, that is to say, it is the most strictly
presentative form of knowledge.

[5] Here and elsewhere I use the word "impression" for the whole complex
of sensation which is present at the moment. It may, perhaps, not be
unnecessary to add that, in employing this term, I am making no
assumption about the independent existence of external objects.

[6] Psychological usage has now pretty well substituted the term "image"
for "idea," in order to indicate an individual (as distinguished from a
general) representation of a sensation or percept. It might, perhaps, be
desirable to go further in this process of differentiating language, and
to distinguish between a sensational image, _e.g._ the representation of
a colour, and a perceptional image, as the representation of a coloured
object. It may be well to add that, in speaking of a fusion of an image
and a sensation, I do not mean that the former exists apart for a single
instant. The term "fusion" is used figuratively to describe the union of
the two sides or aspects of a complete percept.

[7] This impulse to fill in visual elements not actually present is
strikingly illustrated in people's difficulty in recognizing the gap in
the field of vision answering to the insensitive "blind" spot on the
retina. (See Helmholtz, _Physiologische Optik_, p. 573, _et seq._)

[8] This relation will be more fully discussed under the head of

[9] I adopt this distinction from Dr. J. Hughlings Jackson. See his
articles, "On Affections of Speech from Diseases of the Brain," in
_Brain_, Nos. iii. and vii. The second stage might conveniently be named
apperception, but for the special philosophical associations of the
term: _Problems of Life and Mind_, third series, p. 107. This writer
employs the word "preperception" to denote this effect of previous

[10] Such verbal suggestion, moreover, acting through a
sense-impression, has something of that vividness of effect which
belongs to all excitation of mental images by external stimuli.

[11] See Wundt, _Physiologische Psychologie_, p. 723.

[12] For a confirmation of the view adopted in the text, see Professor
Bain, _The Senses and the Intellect_, Part II. ch. i. sec. 8; Herbert
Spencer, _Principles of Psychology_, vol. i. p. 234, _et passim_; Dr.
Ferrier, _The Functions of the Brain_, p. 258, _et seq._; Professor
Wundt, _op. cit._, pp. 644, 645; G. H. Lowes, _Problems of Life and
Mind_, vol. v. p. 445, _et seq._ For an opposite view, see Dr.
Carpenter, _Mental Physiology_, fourth edit., p. 220, etc.; Dr.
Maudsley, _The Physiology of Mind_, ch. v. p. 259, etc.

[13] See note, p. 22.

[14] Touch gives much by way of interpretation only when an individual
object, for example a man's hat, is recognized by aid of this sense
alone, in which case the perception distinctly involves the reproduction
of a complete visual percept. I may add that the organ of smell comes
next to that of hearing, with respect both to the range and definiteness
of its simultaneous sensations, and to the amount of information
furnished by these. A rough sense of distance as well as of direction is
clearly obtainable by means of this organ. There seems to me no reason
why an animal endowed with fine olfactory sensibility, and capable of an
analytic separation of sense elements, should not gain a rough
perception of an external order much more complete than our auditory
perception, which is necessarily so fragmentary. This supposition
appears, indeed, to be the necessary complement to the idea first
broached, so far as I am aware, by Professor Croom Robertson, that to
such animals, visual perception consists in a reference to a system of
muscular feelings defined and bounded by strong olfactory sensations,
rather than by tactual sensations as in our case.

[15] It may be said, perhaps, that the exceptional direction of
attention, by giving an unusual intensity to the impression, causes us
to exaggerate it just as in the case of a novel sensation. An effort of
attention directed to any of our vague bodily sensations easily leads us
to magnify its cause. A similar confusion may arise even in direct
vision, when the objects are looked at in a dim light, through a want of
proper accommodation. (See Sir D. Brewster, _op. cit._, letter i)

[16] They might also be distinguished as objective and subjective
illusions, or as illusions _a posteriori_ and illusions _a priori_.

[17] _Die Schein-Bewegungen_, von Professor Dr. J.I. Hoppe (1879); _cf._
an ingenious article on "Optical Illusions of Motion," by Professor
Silvanus P. Thompson, in _Brain_, October, 1880. These illusions
frequently involve the co-operation of some preconception or
expectation. For example, the apparent movement of a train when we are
watching it and expecting it to move, involves both an element of
sense-impression and of imagination. It is possible that the illusion of
table-turning rests on the same basis, the table-turner being unaware of
the fact of exerting a certain amount of muscular force, and vividly
expecting a movement of the object.

[18] _Physiologische Optik_, p. 316.

[19] It is plain that this supposed error could only be brought under
our definition of illusion by extending the latter, so as to include
sense-perceptions which are contradicted by reason employing idealized
elements of sense-impression, which, as Lewes has shown (_Problems of
Life and Mind_, i. p. 260), make up the "extra-sensible world" of

[20] An ingenious writer, M. Binet, has tried to prove that the fusion
of homogeneous sensations, having little difference of local colour, is
an illustration of this principle. (See the _Revue Philosophique_,
September, 1880.)

[21] Even the fusion of elementary sensations of colour, on the
hypothesis of Young and Helmholtz, in a seemingly simple sensation may
be explained to some extent by these circumstances, more especially the
identity of local interpretation.

[22] The perception of lustre as a single quality seems to illustrate a
like error. There is good reason to suppose that this impression arises
through, a difference of brightness in the two retinal images due to the
regularly reflected light. And so when this inequality of retinal
impression is imitated, as it may easily be by combining a black and a
white surface in a stereoscope, we imagine that we are looking at one
lustrous surface. (See Helmholtz, _Physiologische Optik_, p. 782, etc.,
and _Populäre wissenschaftliche Vorträge_, 2tes Heft, p. 80.)

[23] The conditions of the production of these double images have been
accurately determined by Helmholtz, who shows that the coalescence of
impressions takes place whenever the object is so situated in the field
of vision as to make it practically necessary that it should be
recognized as one.

[24] These illusions are, of course, due in part to inattention, since
close critical scrutiny is often sufficient to dispel them. They are
also largely promoted by a preconception that the event is going to
happen in a particular way. But of this more further on. I may add that
the late Professor Clifford has argued ingeniously against the idea of
the world being a continuum, by extending this idea of the wheel of
life. (See _Lectures and Essays_, i. p. 112, _et seq._)

[25] It is supposed that in the case of every sense-organ there is
always some minimum forces of stimulus at work, the effect of which on
our consciousness is _nil_.

[26] See Helmholtz, _Physiologische Optik_, p. 603. Helmholtz's
explanation is criticised by Dr. Hoppe, in the work already referred to
(sec. vii), though I cannot see that his own theory of these movements
is essentially different. The apparent movement of objects in vertigo,
or giddiness, is probably due to the loss, through a physical cause, of
the impressions made by the pressure of the fluid contents of the ear on
the auditory fibres, by which the sense of equilibrium and of rotation
is usually received. (See Ferrier, _Functions of the Brain_, pp. 60,

[27] I do not need here to go into the question whether, as Johannes
Müller assumed, this is an original attribute of nerve-structure, or
whether, as Wundt suggests, it is due simply to the fact that certain
kinds of nervous fibre have, in the course of evolution, been slowly
adapted to one kind of stimulus.

[28] I here refer to what is commonly supposed to be the vague innate
difference of sensation according to the local origin, before this is
rendered precise, and added to by experience and association.

[29] The illusory character of this simple mode of perception is seen
best, perhaps, in the curious habit into which we fall of referring a
sensation of contact or discomfort to the edge of the teeth, the hair,
and the other insentient structures, and even to anything customarily
attached to the sentient surface, as dress, a pen, graving tool, etc. On
these curious illusions, see Lotze, _Mikrokosmus_, third edit., vol. ii.
p. 202, etc.; Taine, _De l'Intelligence_, tom. ii. p. 83, _et seq._

[30] Quoted by G.H. Lewes, _Problems of Life and Mind_, third series, p.
335. These illusions are supposed to involve an excitation of the
nerve-fibres (whether sensory or motor) which run to the muscles and
yield the so-called muscular sensations.

[31] It is brought out by Griesinger (_loc. cit._) and the other writers
on the pathology of illusion already quoted, that in the case of
subjective sensations of touch, taste, and smell, no sharp line can be
drawn between illusion and hallucination.

[32] For a fuller account of these pathological disturbances of
sensibility, see Griesinger; also Dr. A. Mayer, _Die Sinnestäuschungen_.

[33] Helmholtz, _op. cit._, p. 600, _et seq._ These facts seem to point
to the conclusion that at least some of the feelings by which we know
that we are expending muscular energy are connected with the initial
stage of the outgoing nervous process in the motor centres. In other
pathological conditions the sense of weight by the muscles of the arms
is similarly confused.

[34] Wundt (_Physiologische Psychologie_, p. 653) would exclude from
illusions all those errors of sense-perception which have their
foundation in the normal structure and function of the organs of sense.
Thus, he would exclude the effects of colour-contrast, _e.g._ the
apparent modification of two colours in, juxtaposition towards their
common boundary, which probably arises (according to E. Hering) from
some mutual influence of the temporary state of activity of adjacent
retinal elements. To me, however, these appear to be illusions, since
they may be brought under the head of wrong _interpretations_ of
sense-impressions. When we see a grey patch as rose-red, as though it
were so independently of the action of the complementary light
previously or simultaneously, that is to say, as though it would appear
rose-red to an eye independently of this action, we surely misinterpret.

[35] Quoted by G.H. Lewes, _loc. cit._, p. 257.

[36] The subject of the perception of movement is too intricate to be
dealt with fully here. I have only touched on it so far as necessary to
illustrate our general principle. For a fuller treatment of the subject,
see the work of Dr. Hoppe, already referred to.

[37] The perception of magnitude is closely connected with that of
distance, and is similarly apt to take an illusory form. I need only
refer to the well-known simple optical contrivances for increasing the
apparent magnitude of objects. I ought, perhaps, to add that I do not
profess to give a complete account of optical illusions here, but only
to select a few prominent varieties, with a view to illustrate general
principles of illusion. For a fuller account of the various mechanical
arrangements for producing optical illusion, I must refer the reader to
the writings of Sir D. Brewster and Helmholtz.

[38] Painters are well aware that the colours at the red end of the
spectrum are apt to appear as advancing, while those of the violet end
are known as retiring. The appearance of relief given by a gilded
pattern on a dark blue as ground, is in part referable to the principle
just referred to. In addition, it appears to involve a difference in the
action of the muscles of accommodation in the successive adaptations of
the eye to the most refrangible and the least refrangible rays. (See
Brücke, _Die Physiologie der Farben_, sec. 17.)

[39] Helmholtz tells us (_Populäre wissenschaftliche Vorträge_, 3tes
Heft, p. 64) that even in a stereoscopic arrangement the presence of a
wrong cast shadow sufficed to disturb the illusion.

[40] Among the means of giving a vivid sense of depth to a picture,
emphasized by Helmholtz, is diminishing magnitude. It is obvious that
the perceptions of real magnitude and distance are mutually involved.
When, for example, a picture represents a receding series of objects, as
animals, trees, or buildings, the sense of the third dimension, is
rendered much more clear.

[41] A striking example of this was given in a painting, by Andsell, of
a sportsman in the act of shooting, exhibited in the Royal Academy in

[42] This is at least true of all near objects.

[43] Helmholtz remarks _(op. cit._, p. 628) that the difficulty of
seeing the convex cast as concave is probably due to the presence of the
cast shadow. This has, no doubt, some effect: yet the consideration
urged in the text appears to me to be the most important one.

[44] _Populäre wissenschaftliche Vorträge_, 3tes Heft, pp. 71, 72.

[45] See, on this point, some excellent remarks by G.H. Lewes, _Problems
of Life and Mind_, third series, vol. ii. p. 275.

[46] To some extent this applies to the changes of apparent magnitude
due to altered position. Thus, we do not attend to the reduction of the
height of a small object which we are wont to handle, when it is placed
far below the level of the eye. And hence the error people make in
judging of the point in the wall or skirting which a hat will reach when
placed on the ground.

[47] I refer to the experiments made by Exner, Wundt, and others, in
determining the time elapsing between the giving of a signal to a person
and the execution of a movement in response. "It is found," says Wundt,
"by these experiments that the exact moment at which a sense-impression
is perceived depends on the amount of preparatory self-accommodation of
attention." (See Wundt, _Physiologische Psychologie_, ch. xix.,
especially p. 735. _et seq._)

[48] Quoted by Helmholtz, _op. cit._, p. 626.

[49] When the drawing, by its adherence to the laws of perspective, does
not powerfully determine the eye to see it in one way rather than in the
other (as in Figs. 5 to 7), the disposition to see the one form rather
than the other points to differences in the frequency of the original
forms in our daily experience. At the same time, it is to be observed
that, after looking at the drawing for a time under each aspect, the
suggestion now of the one and now of the other forces itself on the mind
in a curious and unaccountable way.

[50] _Ueber die phantastischen Gesichsterscheinungen_, p. 45.

[51] Another side of histrionic illusion, the reading of the imitated
feelings into the actors' minds, will be dealt with in a later chapter.

[52] In a finished painting of any size this preparation is hardly
necessary. In these cases, in spite of the great deviations from truth
in pictorial representation already touched on, the amount of essential
agreement is so large and so powerful in its effect that even an
intelligent animal will experience an illusion. Mr. Romanes sends me an
interesting account of a dog, that had never been accustomed to
pictures, having been put into a state of great excitement by the
introduction of a portrait into a room, on a level with his eye. It is
not at all improbable that the lower animals, even when sane, are
frequently the subjects of slight illusion. That animals dream is a fact
which is observed as long ago as the age of Lucretius.

[53] This kind of illusion is probably facilitated by the fact that the
eye is often performing slight movements without any clear consciousness
of them. See what was said about the limits of sensibility, p. 50.

[54] _Mental Physiology_, fourth edit., p. 158.

[55] In persons of very lively imagination the mere representation of an
object or event may suffice to bring about such a semblance of
sensation. Thus, M. Taine (_op. cit._, vol. i. p. 94) vouches for the
assertion that "one of the most exact and lucid of modern novelists,"
when working out in his imagination the poisoning of one of his
fictitious characters, had so vivid a gustatory sensation of arsenic
that he was attacked by a violent fit of indigestion.

[56] Mentioned by Dr. Carpenter (_Mental Physiology_, p. 207), where
other curious examples are to be found.

[57] See _Annales Médico-Psychologiques_, tom. vi. p. 168, etc.; tom.
vii. p. 1. etc.

[58] I have already touched on the resonance of a sense-impression when
the stimulus has ceased to act (see p. 55). The remarks in the text hold
good of all such after-impressions, in so far as they take the form of
fully developed percepts. A good example is the recurrence of the images
of microscopic preparations, to which the anatomist is liable. (See
Lewes, _Problems of Life and Mind_, third series, vol. ii. p. 299.)
Since a complete hallucination is supposed to involve the peripheral
regions of the nerve, the mere fact of shutting the eye would not, it is
clear, serve as a test of the origin of the illusion.

[59] That subjective sensation may become the starting-point in complete
hallucination is shown in a curious instance given by Lazarus, and
quoted by Taine, _op. cit._, vol. i. p. 122, _et seq._ The German
psychologist relates that, on one occasion in Switzerland, after gazing
for some time on a chain of snow-peaks, he saw an apparition of an
absent friend, looking like a corpse. He goes on to explain that this
phantom was the product of an image of recollection which somehow
managed to combine itself with the (positive) after-image left by the
impression of the snow-surface.

[60] For an account of Mr. Galton's researches, see _Mind_, No. xix.
Compare, however, Professor Bain's judicious observations on these
results in the next number of _Mind_. The liability of children to take
images for percepts, is illustrated by the experiences related in a
curious little work, _Visions_, by E.H. Clarke, M.D. (Boston, U.S.,
1878), pp. 17, 46, and 212.

[61] A common way of describing the relation of the hallucinatory to
real objects, is to say that the former appear partly to cover and hide
the latter.

[62] Griesinger remarks that the forms of the hallucinations of the
insane rarely depend on sense-disturbances alone. Though these are often
the starting-point, it is the whole mental complexion of the time which
gives the direction to the imagination. The common experience of seeing
rats and mice running about during a fit of _delirium tremens_ very well
illustrates the co-operation of peripheral impressions not usually
attended to, and possibly magnified by the morbid state of sensibility
of the time (in this case flying spots, _muscæ volitantes_), with
emotional conditions. (See Griesinger, _loc. cit._, p. 96.)

[63] Wundt (_Physiologische Psychologie_, p. 652) tells us of an insane
woodman who saw logs of wood on all hands in front of the real objects.

[64] It is stated by Baillarger (Mémoires de l'Académie Royale de
Médicine, tom. xii. p. 273, etc.) that while visual hallucinations are
more frequent than auditory in healthy life, the reverse relation holds
in disease. At the same time, Griesinger remarks (_loc. cit._, p. 98)
that visual hallucinations are rather more common than auditory in
disease also. This is what we should expect from the number of
subjective sensations connected with the peripheral organ of vision. The
greater relative frequency of auditory hallucinations in disease, if
made out, would seem to depend on the close connection between
articulate sounds and the higher centres of intelligence, which centres
are naturally the first to be thrown out of working order. It is
possible, moreover, that auditory hallucinations are quite as common as
visual in states of comparative health, though more easily overlooked.
Professor Huxley relates that he is liable to auditory though not to
visual hallucinations. (See _Elementary Lessons in Physiology_, p. 267.)

[65] See Baillarger, _Mémoires de l'Académie Royale de Médicine_, tom.
xii. p. 273, _et seq._

[66] See Baillarger, _Annales Médico-Psychologiques_, tom. vi. p. 168
_et seq._; also tom. xii. p. 273, _et seq._ Compare Griesinger, _op.
cit._ In a curious work entitled _Du Démon de Socrate_ (Paris, 1856), M.
Lélut seeks to prove that the philosopher's admonitory voice was an
incipient auditory hallucination symptomic of a nascent stage of mental

[67] This is well brought out by Dr. J. Hughlings Jackson, in the papers
in _Brain_, already referred to.

[68] _Friend_, vol. i. p. 248. The story is referred to by Sir W. Scott
in his _Demonology and Witchcraft_.

[69] See E.B. Tylor, _Primitive Culture_, ch. xi.; _cf._ Herbert
Spencer, _Principles of Sociology_, ch. x.

[70] For a fuller account of the different modes of
dream-interpretation, see my article "Dream," in the ninth edition of
the _Encyclopædia Britannica_.

[71] For a fuller account of the reaction of dreams on waking
consciousness, see Paul Radestock, _Schlaf und Traum_. The subject is
touched on later, under the Illusions of Memory.

[72] For an account of the latest physiological hypotheses as to the
proximate cause of sleep, see Radestock, _op. cit._, appendix.

[73] Plutarch, Locke, and others give instances of people who never
dreamt. Lessing asserted of himself that he never knew what it was to

[74] The error touched on here will be fully dealt with under Illusions
of Memory.

[75] For a very full, fair, and thoughtful discussion of this whole
question, see Radestock, _op. cit._, ch. iv.

[76] This may be technically expressed by saying that the liminal
intensity (Schwelle) is raised during sleep.

[77] See Wundt, _Physiologische Psychologie_, pp. 188-191.

[78] There is, indeed, sometimes an undertone of critical reflection,
which is sufficient to produce a feeling of uncertainty and
bewilderment, and in very rare cases to amount to a vague consciousness
that the mental experience is a dream.

[79] _Observations on Man_, Part I. ch. iii, sec. 5.

[80] Quoted by Radestock, _op. cit._, p. 110.

[81] _Le Sommeil et les Rêves_, p. 132, _et seq._

[82] _Das Leben des Traumes_, p. 369. Other instances are related by
Beattie and Abercrombie.

[83] _Le Sommeil et les Rêves_, p. 42, _et seq._

[84] _Beiträge sur Physiognosie und Heautognosie_, p. 256. For other
cases see H. Meyer, _Physiologie der Nervenfaser_, p. 309; and
Strümpell, _Die Natur und Entstehung der Träume_, p. 125.

[85] A very clear and full account of these organic sensations, or
common sensations, has recently appeared from the pen of A. Horwicz in
the _Vierteljahrsschrift für wissenschaftliche Philosophie_, iv.
Jahrgang 3tes Heft.

[86] Schopenhauer uses this hypothesis in order to account for the
apparent reality of dream-illusions. He thinks these internal sensations
may be transformed by the "intuitive function" of the brain (by means of
the "forms" of space, time, etc.) into quasi-realities, just as well as
the subjective sensations of light, sound, etc., which arise in the
organs of sense in the absence of external stimuli. (See _Versuch über
das Geisterschen: Werke_, vol. v. p. 244, _et seq._)

[87] _Das Alpdrücken_, pp. 8, 9, 27.

[88] It is this fact which justifies writers in assigning a prognostic
character to dreams.

[89] A part of the apparent exaggeration in our dream-experiences may be
retrospective, and due to the effect of the impression of wonder which
they leave behind them. (See Strümpell, _Die Natur und Entstehung der

[90] _Cf._ Radestock, _op. cit._, pp. 131, 132.

[91] I was on one occasion able to observe this process going on in the
transition from waking to sleeping. I partly fell asleep when suffering
from toothache. Instantly the successive throbs of pain transformed
themselves into a sequence of visible movements, which I can only
vaguely describe as the forward strides of some menacing adversary.

[92] Even the "unconscious impressions" of waking hours, that is to say,
those impressions which are so fugitive as to leave no psychical trace
behind, may thus rise into the clear light of consciousness during
sleep. Maury relates a curious dream of his own, in which there appeared
a figure that seemed quite strange to him, though he afterwards found
that he must have been in the habit of meeting the original in a street
through which he was accustomed to walk (_loc. cit._, p. 124).

[93] See p. 53.

[94] See Maury, _loc. cit._, p. 146.

[95] See what was said respecting the influence of a dominant emotional
agitation on the interpretation of actual sense-impressions.

[96] It is proved experimentally that the ear has a much closer organic
connection with the vocal organ than the eye has. Donders found that the
period required for responding vocally to a sound-signal is less than
that required for responding in the same way to a light-signal.

[97] On the nature of this impulse, as illustrated in waking and in
sleep, see the article by Delboeuf, "Le Sommeil et les Rêves," in
the _Revue Philosophique_, June, 1880, p. 636.

[98] _Physiologische Psychologie_, p. 660.

[99] I may, perhaps, observe, after giving two dreams which have to do
with mathematical operations, that, though I was very fond of them in my
college days, I have long ceased to occupy myself with these processes.
I would add, by way of redeeming my dream-intelligence from a deserved
charge of silliness, that I once performed a respectable intellectual
feat when asleep. I put together the riddle, "What might a wooden ship
say when her side was stove in? Tremendous!" (Tree-mend-us). I was aware
of having tried to improve on the form of this pun. I am happy to say I
am not given to punning during waking life, though I had a fit of it
once. It strikes me that punning, consisting as it does essentially of
overlooking sense and attending to sound, is just such a debased kind of
intellectual activity as one might look for in sleep.

[100] See Radestock, _op. cit._, ch. ix.; _Vergleichung des Traumes mit
dem Wahnsinn_.

[101] For Spinoza's experience, given in his own words, see Mr. F.
Pollock's _Spinoza_, p. 57; _cf._ what Wundt says on his experience,
_Physiologische Psychologie_, p. 648, footnote 2.

[102] See an interesting account of "Recent Researches on Hypnotism," by
G. Stanley Hall, in _Mind_, January, 1881.

[103] I need hardly observe that physiology shows that there is no
separation of different elementary colour-sensations which are locally

[104] This kind of error is, of course, common to all kinds of
cognition, in so far as they involve comparison. Thus, the presence of
the excitement of the emotion of wonder at the sight of an unusually
large object, say a mountain, disposes the mind to look on it as the
largest of its class. Such illusions come midway between presentative
and representative illusions. They might, perhaps, be specially marked
off as illusions of "judgment."

[105] So far as any mental state, though originating in a fusion of
elements, is now unanalyzable by the best effort of attention, we must
of course regard it in its present form as simple. This distinction
between what is simple or complex in its present nature, and what is
originally so, is sometimes overlooked by psychologists. Whether the
feelings and ideas here referred to are now simple or complex, cannot, I
think, yet be very certainly determined. To take the idea of space, I
find that after practice I recognize the ingredient of muscular feeling
much better than I did at first. And this exactly answers to Helmholtz's
contention that elementary sensations as partial tones can be detected
after practice. Such separate recognition may be said to depend on
correct representation. On the other hand, it must be allowed that there
is room for the intuitionist to say that the associationist is here
reading something into the idea which does not belong to it. It is to be
added that the illusion which the associationist commonly seeks to
fasten on his opponent is that of confusing final with original
simplicity. Thus, he says that, though the idea of space may now to all
intents and purposes be simple, it was really built up out of many
distinct elements. More will be said on the relation of questions of
nature and genesis further on.

[106] I may as well be frank and say that I myself, assuming free-will
to be an illusion, have tried to trace the various threads of influence
which have contributed to its remarkable vitality. (See _Sensation and
Intuition_, ch. v., "The Genesis of the Free-Will Doctrine.")

[107] I purposely leave aside here the philosophical question, whether
the knowledge of others' feelings is intuitive in the sense of being
altogether independent of experience, and the manifestation of a
fundamental belief. The inherited power referred to in the text might,
of course, be viewed as a transmitted result of ancestral experience.

[108] I here assume, along with G.H. Lewes and other competent dramatic
critics, that the actor does not and dares not feel what he expresses,
at least not in the perfectly spontaneous way, and in the same measure
in which he appears to feel it.

[109] The illusory nature of much of this emotional interpretation of
music has been ably exposed by Mr. Gurney. (See _The Power of Sound_, p.
345, _et seq._)

[110] The reader will note that this impulse is complementary to the
other impulse to view all mental states as analogous to impressions
produced by external things, on which I touched in the last chapter.

[111] Errors of memory have sometimes been called "fallacies," as, for
example, by Dr. Carpenter (_Human Physiology_, ch. x.). While preferring
the term "illusion," I would not forget to acknowledge my indebtedness
to Dr. Carpenter, who first set me seriously to consider the subject of
mnemonic error.

[112] From this it would appear to follow that, so far as a percept is
representative, recollection must be re-representative.

[113] The relation of memory to recognition is very well discussed by M.
Delboeuf, in connection with a definition of memory given by
Descartes. (See the article "Le Sommeil et les Rêves," in the _Revue
Philosophique_, April, 1880, p. 428, _et seq._)

[114] A very interesting account of the most recent physiological theory
of memory is to be found in a series of articles, bearing the title, "La
Mémoire comme fait biologique," published in the _Revue Philosophique_,
from the pen of the editor, M. Th. Ribot. (See especially the _Revue_ of
May, 1880, pp. 516, _et seq._) M. Ribot speaks of the modification of
particular nerve-elements as "the static base" of memory, and of the
formation of nerve-connections by means of which the modified element
may be re-excited to activity as "the dynamic base of memory" (p. 535).

[115] What constitutes the difference between such a progressive and a
retrogressive movement is a point that will be considered by-and-by.

[116] It is not easy to say how far exceptional conditions may serve to
reinstate the seemingly forgotten past. Yet the experiences of dreamers
and of those who have been recalled to consciousness after partial
drowning, whatever they may prove with respect to the revivability of
remote experiences, do not lead us to imagine that the range of our
definitely localizing memory is a wide one.

[117] _Der Zeitsinn nach Versuchen_, p. 36, _et seq._

[118] _Physiologische Psychologie_, p. 782.

[119] Wundt refers these errors to variations in the state of
preadjustment of the attention to impressions and representations,
according as they succeed one another slowly or rapidly. There is little
doubt that the effects of the state of tension of the apparatus of
attention, are involved here, though I am disposed to think that Wundt
makes too much of this circumstance. (See _Physiologische Psychologie_,
pp. 782, 783. I have given a fuller account of Wundt's theory in _Mind_,
No. i.)

[120] Strictly speaking, it would occupy more time, since the effort of
recalling each successive link in the chain would involve a greater
interval between any two images than that between the corresponding

[121] I need hardly say that there is no sharp distinction between these
two modes of subjective appreciation. Our estimate of an interval as it
passes is really made up of a number of renewed anticipations and
recollections of the successive experiences. Yet we can say broadly that
this is a prospective estimate, while that which is formed when the
period has quite expired must be altogether retrospective.

[122] See an interesting paper on "Consciousness of Time," by Mr. G. J.
Romanes, in _Mind_ (July, 1878).

[123] It is well known that there is, from the first, a gradual falling
off in the strength of a sensation of light when a moderately bright
object is looked at.

[124] _Cf._ Hartley, _Observations on Man_, Part I. ch. iii. sec. 4
(fifth edit., p. 391).

[125] See Dr. Carpenter's _Mental Physiology_, fourth edit, p. 456.

[126] This is, perhaps, what is meant by saying that people recall their
past enjoyments more readily than their sufferings. Yet much seems to
turn on temperament and emotional peculiarities. (For a fuller
discussion of the point, see my _Pessimism_, p. 344.)

[127] The only exception to this that I can think of is to be found in
the power which I, at least, possess, after looking at a new object, of
representing it as a familiar one. Yet this may be explained by saying
that in the case of every object which is clearly apprehended there must
be vague revivals of _similar_ objects perceived before. Oases in which
recent experiences tend, owing to their peculiar nature, very rapidly to
assume the appearance of old events, will be considered presently.

[128] _Mental Physiology_, p. 456.

[129] _Mental Physiology_, second edit., p. 172.

[130] _Loc. cit._, p. 390.

[131] This source of error has not escaped the notice of autobiographers
themselves. See the remarks of Goethe in the opening passages of his
_Wahrheit und Dichtung_.

[132] One wonders whether those persons who, in consequence of an injury
to their brain, periodically pass from a normal into an abnormal
condition of mind, in each of which there is little or no memory of the
contents of the other state, complete their idea of personal continuity
in each state by the same kind of process as that described in the text.

[133] The reader will remark that this condition of clear intellectual
consciousness, namely, a certain degree of similarity and continuity of
character in our successive mental states, is complementary to the other
condition, constant change, already referred to. It may, perhaps, be
said that all clear consciousness lies between two extremes of excessive
sameness and excessive difference.

[134] It follows that any great transformation of our environment may
lead to a partial confusion with respect to self. For not only do great
and violent changes in our surroundings beget profound changes in our
feelings and ideas, but since the idea of self is under one of its
aspects essentially that of a relation to not-self, any great revolution
in the one term, will confuse the recognition of the other. This fact is
expressed in the common expression that we "lose ourselves" when in
unfamiliar surroundings, and the process of orientation, or "taking our
bearings," fails.

[135] On these disturbances of memory and self-recognition in insanity,
see Griesinger, _op. cit._, pp. 49-51; also Ribot, "Des Désordres
Généraux de la Mémoire," in the _Revue Philosophique_, August, 1880. It
is related by Leuret (_Fragments Psych. sur la Folie_, p. 277) that a
patient spoke of his former self as "la personne de moi-même."

[136] In the following account of the process of belief and its errors,
I am going over some of the ground traversed by my essay on _Belief, its
Varieties and Conditions_ ("Sensation and Intuition," ch. iv.). To this
essay I must refer the reader for a fuller analysis of the subject.

[137] For an account of the difference of mechanism in memory and
expectation, see Taine, _De l'Intelligence_, 2ième partie, livre
premier, ch. ii. sec. 6.

[138] J.S. Mill distinguishes expectation as a radically distinct mode
of belief from memory, but does not bring out the contrast with respect
to activity here emphasized (James Mill's _Analysis of the Human Mind_,
edited by J.S. Mill, p. 411, etc.). For a fuller statement of my view of
the relation of belief to action, as compared with that of Professor
Bain, see my earlier work.

[139] For some good remarks on the logical aspects of future events as
matters of fact, see Mr. Venn's _Logic of Chance_, ch. x.

[140] James Mill's _Analysis of the Human Mind_, edited by J.S. Mill,
vol. i p. 414, _et seq._

[141] _Principles of Geology_, ch. iii.

[142] To make this rough analysis more complete, I ought, perhaps, to
include the effect of all the errors of introspection, memory, and
spontaneous belief, into which the person himself falls, in so far as
they communicate themselves to others.

[143] In the case of a vain woman thinking herself much more pretty than
others think her, the error is still more obviously one connected with a
belief in objective fact.

[144] _The Study of Sociology_, ch. ix.

[145] As a matter of fact, the proportion of accurate knowledge to error
is far larger in the case of classes than of individuals. Propositions
with general terms for subject are less liable to be faulty than
propositions with singular terms for subject.

[146] For a description of each of these extremes of boundless gaiety
and utter despondency, see Griesinger, _op. cit._, Bk. III. ch. i. and
ii. The relation of pessimism to pathological conditions is familiar
enough; less familiar is the relation of unrestrained optimism. Yet
Griesinger writes that among the insane "boundless hilarity," with "a
feeling of good fortune," and a general contentment with everything, is
as frequent as depression and repining (see especially p. 281, also pp.
64, 65).

[147] It has been seen that, from a purely psychological point of view,
even what looks at first like pure presentative cognition, as, for
example, the recognition of a present feeling of the mind, involves an
ingredient of representation.

[148] See especially what was said about the _rationale_ of illusions of
perception, pp. 37, 38.

[149] I say "usually," because, as we have seen, there may sometimes be
a permanent and even an inherited predisposition to active illusion in
the individual temperament and nervous organization.

[150] See what was said on the nature of passive illusions of sense (pp.
44, 68, 70, etc.) The logical character of illusion might be brought out
by saying that it resembles the fallacy which is due to reasoning from
an approximate generalization as though it were a universal truth. In
thus identifying illusion and fallacy, I must not be understood to say
that there is, strictly speaking, any such thing as an unconscious
reasoning process. On the contrary, I hold that it is a contradiction to
talk of any _mental_ operation as altogether unconscious. I simply wish
to show that, by a kind of fiction, illusion may be described as the
result of a series of steps which, if separately unfolded to
consciousness (as they no longer are), would correspond to those of a
process of inference. The fact that illusion arises by a process of
contraction out of conscious inference seems to justify this use of
language, even apart from the fact that the nervous processes in the two
cases are pretty certainly the same.

[151] If we turn from the region of physical to that of moral ideas, we
see this historical collision between common and individual conviction
in a yet more impressive form. The teacher of a new moral truth has
again and again been set down to be an illusionist by a society which
was itself under the sway of a long-reigning error. As George Eliot
observes, "What we call illusions are often, in truth, a wider vision of
past and present realities--a willing movement of a man's soul with the
larger sweep of the world's forces."

[152] To make this account of the philosophic problem of the
object-world complete, I ought to touch not only on the distinction
between the vulgar and the scientific view of material things, but also
on the distinction, within physical science, between the less and the
more abstract view roughly represented by molar and molecular physics.

[153] For an excellent account of the distinction between the scientific
and the philosophic point of view, see Mr. Shadworth Hodgson's
_Philosophy of Reflection_, Bk. I. chs. i. and iii.; also Bk. III. chs.
vii. and viii.

[154] I hold, in spite of Berkeley's endeavours to reconcile his
position with that of common sense, that the popular view does at least
tend in this direction. That is to say, the every-day habit, when
considering the external world, of abstracting from particular minds,
leads on insensibly to that complete detachment of it from mind in
general which expresses itself in the first stage of philosophic
reflection, crude realism. The physicist appears to me, both from the
first essays in Greek "nature-philosophy," as also from the not
infrequent confusion even to-day between a perfectly safe "scientific
materialism" and a highly questionable philosophic materialism, to share
in this tendency to take separate consideration for separate existence.
Each new stage of abstraction in physical science gives birth to a new
attempt to find an independent reality, a thing-in-itself, hidden
further away from sense.

[155] See the interesting autobiographical record of the growth of
philosophic doubt in the _Première Méditation_ of Descartes.

[156] The appeal is not, as we have seen, invariably from sight to
touch, but may be in the reverse direction, as in the recognition of the
duality of the points of a pair of compasses, which seem one to the
tactual sense.

[157] I might further remark that this "collective experience" includes
previously detected illusions of ourselves and of others.

[158] M. Taine frankly teaches that what is commonly called accurate
perception is a "true hallucination" (_De l'Intelligence_, 2ième partie,
Livre I. ch. i. sec. 3).

[159] It only seems to do so, apart from philosophic assumptions, in
certain cases where experience testifies to a uniform untrustworthiness
of the origin. For example, we may, on grounds of matter of fact and
experience, be disposed to distrust any belief that we recognize as
springing from an emotional source, from the mind's feelings and wishes.

I may add that a so-called intuitive belief may refer to a matter of
fact which can be tested by the facts of experience and by scientific
methods. Thus, for example, the old and now exploded form of the
doctrine of innate ideas, which declared that children were born with
certain ideas ready made, might be tested by observation of childhood,
and reasoning from its general intellectual condition. The same applies
to the physiological theories of space-perception, supposed to be based
on Kant's doctrine, put forward in Germany by Johannes Müller and the
"nativistic school." (See my exposition and criticism of these doctrines
in _Mind_, April, 1878, pp. 168-178 and 193-195.)

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