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Title: Astronomy and General Physics Considered with Reference to Natural Theology
Author: Whewell, William
Language: English
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CONSIDERED WITH REFERENCE TO NATURAL THEOLOGY ***
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BRIDGEWATER TREATISES.
CAREY, LEA & BLANCHARD
HAVE PUBLISHED,
ASTRONOMY AND GENERAL PHYSICS, considered with reference to Natural
Theology, by the Rev. WILLIAM WHEWELL, M. A., Fellow and Tutor
of Trinity College, Cambridge; being the _Third Part_ of the
Bridgewater Treatises on the Power, Wisdom, and Goodness of God, as
manifested in the Creation.
The series of Treatises, of which the present is one, is
published under the following circumstances:--
The Right Honourable and Rev. FRANCIS HENRY, Earl of Bridgewater,
died in the month of February, 1825; he directed certain
trustees therein named, to invest in the public funds, the sum
of eight thousand pounds sterling; this sum, with the accruing
dividends thereon, to be held at the disposal of the President,
for the time being, of the Royal Society of London, to be paid
to the person or persons nominated by him. The Testator farther
directed, that the person or persons selected by the said
President, should be appointed to write, print and publish one
thousand copies of a work, on the Power, Wisdom, and Goodness
of God, as manifested in the Creation; illustrating such work,
by all reasonable arguments, as, for instance, the variety and
formation of God’s creatures in the Animal, Vegetable, and
Mineral Kingdoms; the effect of digestion, and, thereby, of
conversion; the construction of the hand of man, and an infinite
variety of other arguments; as also by discoveries, ancient and
modern, in arts, sciences, and the whole extent of literature.
He desired, moreover, that the profits arising from the sale of
the works so published, should be paid to the authors of the
works.
The late President of the Royal Society, DAVIES GILBERT, Esq.,
requested the assistance of his Grace, the Archbishop of
Canterbury, and of the Bishop of London, in determining upon
the best mode of carrying into effect, the intentions of the
Testator. Acting with their advice, and with the concurrence of
a nobleman immediately connected with the deceased, Mr. Davies
Gilbert appointed the following eight gentlemen to write separate
Treatises in the different branches of the subjects here stated:--
I. The Adaptation of External Nature to the Moral and
Intellectual Constitution of Man, by the Rev. THOMAS CHALMERS, D.
D., Professor of Divinity in the University of Edinburgh.
II. The Adaptation of External Nature to the Physical Condition
of Man, by JOHN KIDD, M. D., F. R. S., Regius Professor of
Medicine in the University of Oxford.
III. Astronomy and General Physics, considered with reference to
Natural Theology, by the Rev. WILLIAM WHEWELL, M. A., F. R. S.,
Fellow of Trinity College, Cambridge.
IV. The Hand: its Mechanism and Vital Endowments as evincing
Design, by Sir CHARLES BELL, K. H., F. R. S.
V. Animal and Vegetable Physiology, by PETER MARK ROGET, M. D.,
Fellow of and Secretary to the Royal Society.
VI. Geology and Mineralogy, by the Rev. WILLIAM BUCKLAND, D. D.,
F. R. S., Canon of Christ Church, and Professor of Geology in the
University of Oxford.
VII. The History, Habits, and Instincts of Animals, by the Rev.
WILLIAM KIRBY, M. A., F. R. S.
VIII. Chemistry, Meteorology, and the Function of Digestion, by
WILLIAM PROUT, M. D., F. R. S.
_The whole of these Treatises are nearly finished, and will be
put to press as soon as received, and published in a cheap and
handsome form._
THE PRINCIPLES OF CHRISTIAN PHILOSOPHY; containing the Doctrines,
Duties, Admonitions, and Consolations of the Christian Religion, by
JOHN BURNS, M. D., F. R. S. From the fourth London edition. In the
press.
CONVERSATIONS WITH LORD BYRON ON THE SUBJECT OF RELIGION. By J.
KENNEDY, M. D. 12mo.
GLEANINGS IN NATURAL HISTORY, WITH LOCAL RECOLLECTIONS. By EDWARD
JESSE, Esq. To which are added, Maxims and Hints for Anglers. From
the second London edition, in one volume, being a Companion to the
Journal of a Naturalist.
We have occasionally selected a paragraph from a very pretty
volume, by Mr. Jesse, published under the above title. The
author lives in the neighbourhood of Kew, and like Mr. White
of Selborne,--who made a small village of Hampshire one of the
most interesting spots to the lover of nature, by his ample
descriptions of the natural objects which he saw around him,--Mr.
Jesse has rendered his walks a vehicle for much instruction and
amusement to himself and to others. He principally confines
his attention to zoology--the most generally attractive of the
departments of natural history; and he looks upon the animal
world with so much practical wisdom, being disposed to be happy
himself, and to see every creature around him happy, that there
are few persons who will not read his slight sketches with
improvement to their hearts and understandings.--_Penny Magazine._
THE MECHANISM OF THE HEAVENS. By Mrs. SOMERVILLE. In 18mo.
Is it asking too much of Mrs. Somerville to express a hope that
she will allow this beautiful preliminary Dissertation to be
printed separately for the delight and instruction of thousands
of readers, young and old, who cannot understand, or are too
indolent to apply themselves to the more elaborate parts of the
work? If she will do this, we hereby promise to exert our best
endeavours to make its merits known.--_Literary Gazette._
SALMONIA; OR, DAYS OF FLY FISHING. By Sir H. DAVY.
We are surprised in meeting with an American reprint of this
delightful volume, that a work so universally popular has not
been before republished in this country.--_N. Y. American._
One of the most delightful labours of leisure ever seen; not a
few of the most beautiful phenomena of nature are here lucidly
explained.--_Gent. Magazine._
THE NATURAL HISTORY OF SELBORNE. By the late Rev. GILBERT WHITE,
A. M., Fellow of the Oriel College, Oxford; with additions by Sir
WILLIAM JARDINE, Bart. F. R. S., E. F. L. S., M. W. S., author of
“Illustrations of Ornithology.”
White’s History of Selborne, the most fascinating piece of rural
writing and sound English philosophy that has ever issued from
the press.--_Athenæum._
JOURNAL OF A NATURALIST. With Plates.
----Plants, trees, and stones we note;
Birds, insects, beasts and rural things.
We again most strongly recommend this little unpretending volume
to the attention of every lover of nature, and more particularly
of our country readers. It will induce them, we are sure, to
examine more closely than they have been accustomed to do, into
the objects of animated nature, and such examination will prove
one of the most innocent, and the most satisfactory sources of
gratification and amusement. It is a book that ought to find its
way into every rural drawing-room in the kingdom, and one that
may safely be placed in every lady’s boudoir, be her rank and
station in life what they may.--_Quart. Review_, No. LXXVIII.
This is a most delightful book on the most delightful of all
studies. We are acquainted with no previous work which bears
any resemblance to this, except “White’s History of Selborne,”
the most fascinating piece of rural writing and sound English
philosophy that ever issued from the press.--_Athenæum._
THE FAMILY CABINET ATLAS, constructed upon an original plan: being
a Companion to the Encyclopædia Americana, Cabinet Cyclopædia,
Family Library, Cabinet Library, &c.
[This Atlas comprises, in a volume of the Family Library size,
nearly one hundred Maps and Tables, which present equal to _fifty
thousand names of places_; a body of information three times as
extensive as that supplied by the generality of _Quarto Atlases_.]
This beautiful and most useful little volume, says the Literary
Gazette, is a perfect picture of elegance, containing a vast sum
of geographical information. A more instructive little present,
or a gift better calculated to be long preserved and often
referred to, could not be offered to favoured youth of either
sex. Its cheapness, we must add, is another recommendation; for,
although this elegant publication contains one hundred beautiful
engravings, it is issued at a price that can be no obstacle to
its being procured by every parent and friend to youth.
This Atlas far surpasses any thing of the kind which we have
seen, and is made to suit the popular libraries which Dr.
Lardner and Mr. Murray are now sending into every family in the
empire.--_Monthly Review._
Its very ingenious method of arrangement secures to the
geographical student the information for which hitherto
he has been obliged to resort to works of the largest
dimensions.--_Athenæum._
THE RECTORY OF VALEHEAD. By the Rev. ROBERT WILSON EVANS, M. A.
Universally and cordially do we recommend this delightful volume.
Impressed with the genuine spirit of Christianity; a diary, as it
were, of the feelings, hopes, and sorrows of a family,--it comes
home to all, either in sympathy or example. It is a beautiful
picture of a religious household, influencing to excellence all
within its sphere. We believe no person could read this work, and
not be better for its pious touching lessons.--_Literary Gaz._
We fearlessly pronounce this delightful little volume to be
not only one of the most faultless, but every way valuable
works it has ever fallen to our lot to recommend to public
perusal.--_Stamford Herald._
The Rectory of Valehead is a beautiful model of domestic life
in the Christian home of a well-regulated family, and combines
literary amusement with the most refined and intellectual
improvement.--_Scotsman._
A GENERAL VIEW OF THE PROGRESS OF ETHICAL PHILOSOPHY, chiefly
during the Seventeenth and Eighteenth Centuries. By Sir JAMES
MACKINTOSH, M. P. In 8vo.
The best offspring of the pen of an author who in philosophical
spirit, knowledge and reflection, richness of moral sentiment,
and elegance of style, has altogether no superior--perhaps no
equal--among his contemporaries. Some time ago we made copious
extracts from the beautiful work. We could not recommend the
whole too earnestly.--_National Gazette._
THE BOOK OF THE SEASONS; OR THE CALENDAR OF NATURE. By WILLIAM
HOWITT. In one volume, 12mo.
THE BRIDGEWATER TREATISES
ON THE POWER, WISDOM, AND GOODNESS OF GOD
AS MANIFESTED IN THE CREATION.
TREATISE III.
ON ASTRONOMY AND GENERAL PHYSICS.
BY THE REV. W. WHEWELL.
ET HÆC DE DEO, DE QUO UTIQUE EX PHÆNOMENIS DISSERERE AD
PHILOSOPHIAM NATURALEM PERTINET.
NEWTON, CONCLUSION OF THE PRINCIPIA.
ASTRONOMY AND GENERAL PHYSICS
CONSIDERED WITH REFERENCE TO
NATURAL THEOLOGY.
BY THE
REV. WILLIAM WHEWELL, M. A.
FELLOW AND TUTOR OF TRINITY COLLEGE,
CAMBRIDGE.
Philadelphia:
CAREY, LEA & BLANCHARD,
CHESTNUT STREET.
1833.
TO THE
RIGHT HONOURABLE AND RIGHT REVEREND
CHARLES JAMES,
LORD BISHOP OF LONDON.
MY LORD--
I owe it to you that I was selected for the task attempted in the
following pages, a distinction which I feel to be honourable;
and on this account alone I should have a peculiar pleasure in
dedicating the work to your lordship. I do so with additional
gratification on another account: the Treatise has been written
within the walls of the College of which your lordship was formerly
a resident member, and its merits, if it have any, are mainly
due to the spirit and habits of the place. The society is always
pleased and proud to recollect that a person of the eminent talents
and high character of your lordship is one of its members; and I
am persuaded that any effort in the cause of letters and religion
coming from that quarter, will have for you an interest beyond what
it would otherwise possess.
The subject proposed to me was limited: my prescribed object is to
lead the friends of religion to look with confidence and pleasure
on the progress of the physical sciences, by showing how admirably
every advance in our knowledge of the universe harmonizes with
the belief of a most wise and good God. To do this effectually
may be, I trust, a useful labour. Yet, I feel most deeply, what
I would take this occasion to express, that this, and all that
the speculator concerning Natural Theology can do, is utterly
insufficient for the great ends of Religion; namely, for the
purpose of reforming men’s lives, of purifying and elevating their
characters, of preparing them for a more exalted state of being. It
is the need of something fitted to do this, which gives to religion
its vast and incomparable importance; and this can, I well know, be
achieved only by that Revealed Religion of which we are ministers,
but on which the plan of the present work did not allow me to dwell.
That Divine Providence may prosper the labours of your lordship,
and of all who are joined with you in the task of maintaining and
promoting _this_ Religion, is, my lord, the earnest wish and prayer
of
Your very faithful
And much obliged servant,
WILLIAM WHEWELL.
Trinity College, Cambridge,
Feb. 25, 1833.
NOTICE.
The series of Treatises, of which the present is one, is published
under the following circumstances:
The RIGHT HONOURABLE and REVEREND FRANCIS HENRY, EARL OF
BRIDGEWATER, died in the month of February, 1829; and by his last
Will and Testament, bearing date the 25th of February, 1825, he
directed certain Trustees therein named to invest in the public
funds the sum of Eight thousand pounds sterling; this sum, with
the accruing dividends thereon, to be held at the disposal of the
President, for the time being, of the Royal Society of London, to
be paid to the person or persons nominated by him. The Testator
further directed, that the person or persons selected by the said
President should be appointed to write, print, and publish one
thousand copies of a work _On the Power, Wisdom, and Goodness of
God, as manifested in the Creation; illustrating such work by all
reasonable arguments, as for instance the variety and formation
of God’s creatures in the animal, vegetable, and mineral
kingdoms; the effect of digestion, and thereby of conversion;
the construction of the hand of man, and an infinite variety of
other arguments; as also by discoveries ancient and modern, in
arts, sciences, and the whole extent of literature_. He desired,
moreover, that the profits arising from the sale of the works so
published should be paid to the authors of the works.
The late President of the Royal Society, Davies Gilbert,
Esq. requested the assistance of his Grace the Archbishop of
Canterbury and of the Bishop of London, in determining upon
the best mode of carrying into effect the intentions of the
Testator. Acting with their advice, and with the concurrence of
a nobleman immediately connected with the deceased, Mr. Davies
Gilbert appointed the following eight gentlemen to write separate
Treatises on the different branches of the subject as here stated:
THE REV. THOMAS CHALMERS, D. D.
Professor of Divinity in the University of Edinburgh.
ON THE ADAPTATION OF EXTERNAL NATURE TO THE MORAL AND
INTELLECTUAL CONSTITUTION OF MAN.
JOHN KID, M. D. F. R. S.
Regius Professor of Medicine in the University of Oxford.
ON THE ADAPTATION OF EXTERNAL NATURE TO THE PHYSICAL
CONDITION OF MAN.
THE REV. WILLIAM WHEWELL, M. A. F. R. S.
Fellow of Trinity College, Cambridge.
ON ASTRONOMY AND GENERAL PHYSICS.
SIR CHARLES BELL, K. H. F. R. S,
THE HAND: ITS MECHANISM AND VITAL ENDOWMENTS AS EVINCING
DESIGN.
PETER MARK ROGET, M. D.
Fellow of and Secretary to the Royal Society.
ON ANIMAL AND VEGETABLE PHYSIOLOGY.
THE REV. WILLIAM BUCKLAND, D. D. F. R. S.
Canon of Christ Church, and Professor of Geology in the University of Oxford.
ON GEOLOGY AND MINERALOGY.
THE REV. WILLIAM KIRBY, M. A. F. R. S.
ON THE HISTORY, HABITS, AND INSTINCTS OF ANIMALS.
WILLIAM PROUT, M. D. F. R. S.
ON CHEMISTRY, METEOROLOGY, AND THE FUNCTION OF DIGESTION.
HIS ROYAL HIGHNESS THE DUKE OF SUSSEX, President of the Royal
Society, having desired that no unnecessary delay should take
place in the publication of the above mentioned treatises, they
will appear at short intervals, as they are ready for publication.
CONTENTS.
[Within the last year or two, several works have been published in
this country on subjects more or less closely approaching to that
here treated. It may, therefore, be not superfluous to say that the
author of the following pages believes that he has not borrowed
any of his views or illustrations from recent English writers on
Natural Theology.]
Page.
INTRODUCTION.
CHAPTER I. Object of the Present Treatise 13
II. On Laws of Nature 17
III. Mutual Adaptation of Laws of Nature 20
IV. Division of the Subject 23
BOOK I. TERRESTRIAL ADAPTATIONS 25
CHAPTER I. The Length of the Year 28
II. The Length of the Day 37
III. The Mass of the Earth 43
IV. The Magnitude of the Ocean 50
V. The Magnitude of the Atmosphere 51
VI. The Constancy and Variety of Climates 52
VII. The Variety of Organization corresponding
to the Variety of Climate 57
VIII. The Constituents of Climate 66
The Laws of Heat with respect to the Earth 67
IX. The Laws of Heat with respect to Water 70
X. The Laws of Heat with respect to Air 81
XI. The Laws of Electricity 91
XII. The Laws of Magnetism 93
XIII. The Properties of Light with regard to
Vegetation 94
XIV. Sound 96
XV. The Atmosphere 102
XVI. Light 104
XVII. The Ether 111
XVIII. Recapitulation 113
BOOK II. COSMICAL ARRANGEMENTS 119
CHAPTER I. The Structure of the Solar System 121
II. The Circular Orbits of the Planets round the Sun 123
III. The Stability of the Solar System 127
IV. The Sun in the Centre 134
V. The Satellites 137
VI. The Stability of the Ocean 140
VII. The Nebular Hypothesis 143
VIII. The Existence of a Resisting Medium in the
Solar System 150
IX. Mechanical Laws 163
X. The Law of Gravitation 166
XI. The Laws of Motion 178
XII. Friction 183
BOOK III. RELIGIOUS VIEWS 193
CHAPTER I. The Creator of the Physical World is the
Governor of the Moral World 195
II. On the Vastness of the Universe 205
III. On Man’s Place in the Universe 212
IV. On the Impression produced by the Contemplation
of Laws of Nature; or, on the Conviction
that Law implies Mind 223
V. On Inductive Habits; or, on the impression
produced on Men’s Minds by discovering
Laws of Nature 230
VI. On Deductive Habits; or, on the Impression
produced on Men’s Minds by tracing
the Consequences of ascertained Laws 243
VII. On Final Causes 257
VIII. On the Physical Agency of the Deity 267
IX. On the Impression produced by considering
the Nature and Prospects of Science;
or, on the Impossibility of the Progress
of our Knowledge ever enabling us to
comprehend the Nature of the Deity 273
ON
ASTRONOMY
AND
GENERAL PHYSICS.
INTRODUCTION.
CHAPTER I.
_Object of the Present Treatise._
The examination of the material world brings before us a number
of things and relations of things which suggest to most minds
the belief of a creating and presiding Intelligence. And this
impression, which arises with the most vague and superficial
consideration of the objects by which we are surrounded, is, we
conceive, confirmed and expanded by a more exact and profound study
of external nature. Many works have been written at different
times with the view of showing how our knowledge of the elements
and their operation, of plants and animals and their construction,
may serve to nourish and unfold our idea of a Creator and Governor
of the world. But though this is the case, a new work on the same
subject may still have its use. Our views of the Creator and
Governor of the world, as collected from or combined with our
views of the world itself, undergo modifications, as we are led by
new discoveries, new generalizations, to regard nature in a new
light. The conceptions concerning the Deity, his mode of effecting
his purposes, the scheme of his government, which are suggested
by one stage of our knowledge of natural objects and operations,
may become manifestly imperfect or incongruous, if adhered to and
applied at a later period, when our acquaintance with the immediate
causes of natural events has been greatly extended. On this account
it may be interesting, after such an advance, to show how the views
of the creation, preservation, and government of the universe,
which natural science opens to us, harmonize with our belief in
a Creator, Governor, and Preserver of the world. To do this with
respect to certain departments of Natural Philosophy is the object
of the following pages; and the author will deem himself fortunate,
if he succeeds in removing any of the difficulties and obscurities
which prevail in men’s minds, from the want of a clear mutual
understanding between the religious and the scientific speculator.
It is needless here to remark the necessarily imperfect and scanty
character of Natural Religion; for most persons will allow that,
however imperfect may be the knowledge of a Supreme Intelligence
which we gather from the contemplation of the natural world, it
is still of most essential use and value. And our purpose on this
occasion is, not to show that Natural Theology is a perfect and
satisfactory scheme, but to bring up our Natural Theology to the
point of view in which it may be contemplated by the aid of our
Natural Philosophy.
Now the peculiar point of view which at present belongs to Natural
Philosophy, and especially to the departments of it which have been
most successfully cultivated, is, that nature, so far as it is an
object of scientific research, is a collection of facts governed by
_laws_: our knowledge of nature is our knowledge of laws; of laws
of operation and connexion, of laws of succession and co-existence,
among the various elements and appearances around us. And it must
therefore here be our aim to show how this view of the universe
falls in with our conception of the Divine Author, by whom we hold
the universe to be made and governed.
_Nature acts by general laws_; that is, the occurrences of the
world in which we find ourselves, result from causes which operate
according to fixed and constant rules. The succession of days,
and seasons, and years, is produced by the motions of the earth;
and these again are governed by the attraction of the sun, a
force which acts with undeviating steadiness and regularity. The
changes of winds and skies, seemingly so capricious and casual,
are produced by the operation of the sun’s heat upon air and
moisture, land and sea; and though in this case we cannot trace
the particular events to their general causes, as we can trace
the motions of the sun and moon, no philosophical mind will doubt
the generality and fixity of the rules by which these causes act.
The variety of the effects takes place, because the circumstances
in different cases vary; and not because the action of material
causes leaves anything to chance in the result. And again, though
the vital movements which go on in the frame of vegetables and
animals depend on agencies still less known, and probably still
more complex, than those which rule the weather, each of the powers
on which such movements depend has its peculiar laws of action,
and these are as universal and as invariable as the law by which a
stone falls to the earth when not supported.
The world then is governed by general laws; and in order to
collect from the world itself a judgment concerning the nature
and character of its government, we must consider the import and
tendency of such laws, so far as they come under our knowledge. If
there be, in the administration of the universe, intelligence and
benevolence, superintendence and foresight, grounds for love and
hope, such qualities may be expected to appear in the constitution
and combination of those fundamental regulations by which the
course of nature is brought about, and made to be what it is.
If a man were, by some extraordinary event, to find himself in a
remote and unknown country, so entirely strange to him that he
did not know whether there existed in it any law or government at
all; he might in no long time ascertain whether the inhabitants
were controlled by any superintending authority; and with a little
attention he might determine also whether such authority were
exercised with a prudent care for the happiness and well-being
of its subjects, or without any regard and fitness to such ends;
whether the country were governed by laws at all, and whether the
laws were good. And according to the laws which he thus found
prevailing, he would judge of the sagacity, and the purposes of the
legislative power.
By observing the laws of the material universe and their operation,
we may hope, in a somewhat similar manner, to be able to direct
our judgment concerning the government of the universe: concerning
the mode in which the elements are regulated and controlled, their
effects combined and balanced. And the general tendency of the
results thus produced may discover to us something of the character
of the power which has legislated for the material world.
We are not to push too far the analogy thus suggested. There is
undoubtedly a wide difference between the circumstances of man
legislating for man, and God legislating for matter. Still we
shall, it will appear, find abundant reason to admire the wisdom
and the goodness which have established _the Laws of Nature_,
however rigorously we may scrutinize the import of this expression.
CHAPTER II.
_On Laws of Nature._
When we speak of material nature as being governed by _laws_, it
is sufficiently evident that we use the term in a manner somewhat
metaphorical. The laws to which man’s attention is primarily
directed are _moral_ laws; rules laid down for his actions; rules
for the conscious actions of a person; rules which, as a matter
of possibility, he may obey or may transgress; the latter event
being combined, not with an impossibility, but with a penalty. But
the _Laws of Nature_ are something different from this; they are
rules for that which _things_ are to do and suffer; and this by
no consciousness or will of theirs. They are rules describing the
mode in which things _do_ act; they are invariably obeyed; their
transgression is not punished, it is excluded. The language of a
moral law is, man _shall_ not kill; the language of a Law of Nature
is, a stone _will_ fall to the earth.
These two kinds of laws direct the actions of persons and of
things, by the sort of control of which persons and things are
respectively susceptible; so that the metaphor is very simple; but
it is proper for us to recollect that it is a metaphor, in order
that we may clearly apprehend what is implied in speaking of the
Laws of Nature.
In this phrase are included all properties of the portions of
the material world; all modes of action and rules of causation,
according to which they operate on each other. The whole course of
the visible universe therefore is but the collective result of such
laws; its movements are only the aggregate of _their_ working. All
natural occurrences, in the skies and on the earth, in the organic
and in the inorganic world, are determined by the relations of the
elements and the actions of the forces of which the rules are thus
prescribed.
The relations and rules by which these occurrences are thus
determined necessarily depend on measures of time and space,
motion and force; on quantities which are subject to numerical
measurement, and capable of being connected by mathematical
properties. And thus all things are ordered by number and weight
and measure. “God,” as was said by the ancients, “works by
geometry:” the legislation of the material universe is necessarily
delivered in the language of mathematics; the stars in their
courses are regulated by the properties of conic sections, and
the winds depend on arithmetical and geometrical progressions of
elasticity and pressure.
The constitution of the universe, so far as it can be clearly
apprehended by our intellect, thus assumes a shape involving an
assemblage of mathematical propositions: certain algebraical
formulæ, and the knowledge when and how to apply them, constitute
the last step of the physical science to which we can attain.
The labour and the endowments of ages have been employed in
bringing such science into the condition in which it now exists;
and an exact and extensive discipline in mathematics, followed
by a practical and profound study of the researches of natural
philosophers, can alone put any one in possession of the knowledge
concerning the course of the material world, which is at present
open to man. The general impression, however, which arises from
the view thus obtained of the universe, the results which we
collect from the most careful scrutiny of its administration, may,
we trust, be rendered intelligible without this technical and
laborious study, and to do this is our present object.
It will be our business to show that the laws which really prevail
in nature are, by their _form_, that is, by the nature of the
connexion which they establish among the quantities and properties
which they regulate, remarkably adapted to the office which is
assigned them; and thus offer evidence of selection, design, and
goodness, in the power by which they were established. But these
characters of the legislation of the universe may also be seen, in
many instances, in a manner somewhat different from the selection
of the law. The _nature of the connexion_ remaining the same, the
quantities which it regulates may also in their _magnitude_ bear
marks of selection and purpose. For the law may be the same while
the quantities to which it applies are different. The law of the
gravity which acts to the earth and to Jupiter, is the same; but
the intensity of the force at the surfaces of the two planets is
different. The law which regulates the density of the air at any
point, with reference to the height from the earth’s surface,
would be the same, if the atmosphere were ten times as large, or
only one-tenth as large as it is; if the barometer at the earth’s
surface stood at three inches only, or if it showed a pressure of
thirty feet of mercury.
Now this being understood, the adaptation of a law to its purpose,
or to other laws, may appear in two ways:--either in the form of
the law, or in the amount of the magnitudes which it regulates,
which are sometimes called _arbitrary magnitudes_.
If the attraction of the sun upon the planets did not vary
inversely as the square of the distance, the _form_ of the law
of gravitation would be changed; if this attraction were, at the
earth’s orbit, of a different _value_ from its present one, the
arbitrary magnitude would be changed; and it will appear, in a
subsequent part of this work, that either change would, so far as
we can trace its consequences, be detrimental. The form of the law
determines in what manner the facts shall take place; the arbitrary
magnitude determines how fast, how far, how soon; the one gives a
model, the other a measure of the phenomenon; the one draws the
plan, the other gives the scale on which it is to be executed; the
one gives the rule, the other the rate. If either were wrongly
taken, the result would be wrong too.
CHAPTER III.
_Mutual Adaptation in the Laws of Nature._
To ascertain such laws of nature as we have been describing, is
the peculiar business of science. It is only with regard to a very
small portion of the appearances of the universe, that science, in
any strict application of the term, exists. In very few departments
of research have men been able to trace a multitude of known facts
to causes which appear to be the ultimate material causes, or to
discern the laws which seem to be the most general laws. Yet, in
one or two instances, they have done this, or something approaching
to this; and most especially in the instance of that part of
nature, which it is the object of this treatise more peculiarly to
consider.
The apparent motions of the sun, moon, and stars have been more
completely reduced to their causes and laws than any other class of
phenomena. Astronomy, the science which treats of these, is already
a wonderful example of the degree of such knowledge which man may
attain. The forms of its most important laws may be conceived to
be certainly known; and hundreds of observers in all parts of the
world are daily employed in determining, with additional accuracy,
the arbitrary magnitudes which these laws involve.
The inquiries in which the mutual effects of heat, moisture,
air, and the like elements are treated of, including, among
other subjects, all that we know of the causes of the weather
(meteorology) is a far more imperfect science than astronomy. Yet,
with regard to these agents, a great number of laws of nature have
been discovered, though, undoubtedly, a far greater number remain
still unknown.
So far, therefore, as our knowledge goes, astronomy and meteorology
are parts of natural philosophy in which we may study the order
of nature with such views as we have suggested; in which we may
hope to make out the adaptations and aims which exist in the laws
of nature; and thus to obtain some light on the tendency of this
part of the legislation of the universe, and on the character and
disposition of the Legislator.
The number and variety of the laws which we find established in
the universe is so great, that it would be idle to endeavour
to enumerate them. In their operation they are combined and
intermixed in incalculable and endless perplexity, influencing
and modifying each other’s effects in every direction. If we
attempt to comprehend at once the whole of this complex system,
we find ourselves utterly baffled and overwhelmed by its extent
and multiplicity. Yet, in so far as we consider the bearing of
one part upon another, we receive an impression of adaptation, of
mutual fitness, of conspiring means, of preparation and completion,
of purpose and provision. This impression is suggested by the
contemplation of every part of nature; but the grounds of it, from
the very circumstances of the case, cannot be conveyed in a few
words. It can only be fully educed by leading the reader through
several views and details, and must grow out of the combined
influence of these on a sober and reflecting frame of mind. However
strong and solemn be the conviction which may be derived from a
contemplation of nature, concerning the existence, the power, the
wisdom, the goodness of our Divine Governor, we cannot expect that
this conviction, as resulting from the extremely complex spectacle
of the material world, should be capable of being irresistibly
conveyed by a few steps of reasoning, like the conclusion of
a geometrical proposition, or the result of an arithmetical
calculation.
We shall, therefore, endeavour to point out cases and circumstances
in which the different parts of the universe exhibit this mutual
adaptation, and thus to bring before the mind of the reader the
evidence of wisdom and providence, which the external world
affords. When we have illustrated the correspondencies which
exist in every province of nature, between the qualities of brute
matter and the constitution of living things, between the tendency
to derangement and the conservative influences by which such a
tendency is counteracted, between the office of the minutest speck
and of the most general laws; it will, we trust, be difficult or
impossible to exclude from our conception of this wonderful system,
the idea of a harmonizing, a preserving, a contriving, an intending
Mind; of a Wisdom, Power, and Goodness far exceeding the limits of
our thoughts.
CHAPTER IV.
_Division of the Subject._
In making a survey of the universe, for the purpose of pointing
out such correspondencies and adaptations as we have mentioned, we
shall suppose the general leading facts of the course of nature
to be known, and the explanations of their causes now generally
established among astronomers and natural philosophers to be
conceded. We shall assume therefore that the earth is a solid
globe of ascertained magnitude, which travels round the sun, in
an orbit nearly circular, in a period of about three hundred and
sixty-five days and a quarter, and in the mean time revolves, in an
inclined position, upon its own axis in about twenty-four hours,
thus producing the succession of appearances and effects which
constitute seasons and climates, day and night;--that this globe
has its surface furrowed and ridged with various inequalities,
the waters of the ocean occupying the depressed parts:--that it
is surrounded by an atmosphere, or spherical covering of air;
and that various other physical agents, moisture, electricity,
magnetism, light, operate at the surface of the earth, according to
their peculiar laws. This surface is, as we know, clothed with a
covering of plants, and inhabited by the various tribes of animals,
with all their variety of sensations, wants, and enjoyments. The
relations and connexions of the larger portions of the world, the
sun, the planets, and the stars, the _cosmical_ arrangements of
the system, as they are sometimes called, determine the course
of events among these bodies; and the more remarkable features
of these arrangements are therefore some of the subjects for our
consideration. These cosmical arrangements, in their consequences,
affect also the physical agencies which are at work at the surface
of the earth, and hence come in contact with _terrestrial_
occurrences. They thus influence the functions of plants and
animals. The circumstances in the cosmical system of the universe,
and in the organic system of the earth, which have thus a bearing
on each other, form another of the subjects of which we shall
treat. The former class of considerations attends principally to
the stability and other apparent perfections of the solar system;
the latter to the well-being of the system of organic life by which
the earth is occupied. The two portions of the subject may be
treated as Cosmical Arrangements and Terrestrial Adaptations.
We shall begin with the latter class of adaptations, because in
treating of these the facts are more familiar and tangible, and the
reasonings less abstract and technical, than in the other division
of the subject. Moreover, in this case men have no difficulty
in recognizing as desirable the end which is answered by such
adaptations, and they therefore the more readily consider it _as
an end_. The nourishment, the enjoyment, the diffusion of living
things, are willingly acknowledged to be a suitable object for
contrivance; the simplicity, the permanence, of an inert mechanical
combination might not so readily be allowed to be a manifestly
worthy aim of a Creating Wisdom. The former branch of our argument
may therefore be best suited to introduce to us the Deity as the
institutor of Laws of Nature, though the latter may afterwards give
us a wider view and a clearer insight into one province of his
legislation.
BOOK I.
TERRESTRIAL ADAPTATIONS.
We proceed in this book to point out relations which subsist
between the laws of the inorganic world, that is, the general facts
of astronomy and meteorology; and the laws which prevail in the
organic world, the properties of plants and animals.
With regard to the first kind of laws, they are in the highest
degree various and unlike each other. The intensity and activity
of natural influences follow in different cases the most different
rules. In some instances they are _periodical_, increasing and
diminishing alternately, in a perpetual succession of equal
intervals of time. This is the case with the heat at the earth’s
surface, which has a period of a year; with the light, which has a
period of a day. Other qualities are _constant_, thus the force of
gravity at the same place is always the same. In some cases, a very
simple cause produces very complicated effects; thus the globular
form of the earth, and the inclination of its axis during its
annual motion, give rise to all the variety of climates. In other
cases a very complex and variable system of causes produces effects
comparatively steady and uniform; thus solar and terrestrial heat,
air, moisture, and probably many other apparently conflicting
agents, join to produce our weather, which never deviates very far
from a certain average standard.
Now a general fact, which we shall endeavour to exemplify in the
following chapters, is this:--That those properties of plants and
animals which have reference to agencies of a periodical character,
have also by their nature a periodical mode of working; while
those properties which refer to agencies of constant intensity,
are adjusted to this constant intensity: and again, there are
peculiarities in the nature of organized beings which have
reference to a variety in the conditions of the external world,
as, for instance, the difference of the organized population of
different regions: and there are other peculiarities which have
a reference to the constancy of the average of such conditions,
and the limited range of the deviations from that average; as for
example, that constitution by which each plant and animal is fitted
to exist and prosper in its usual place in the world.
And not only is there this general agreement between the nature of
the laws which govern the organic and inorganic world, but also
there is a coincidence between the _arbitrary magnitudes_ which
such laws involve on the one hand and on the other. Plants and
animals have, in their construction, certain periodical functions,
which have a reference to alternations of heat and cold; the
length of the period which belongs to these functions by their
construction, appears to be that of the period which belongs to the
actual alternations of heat and cold, namely, a year. Plants and
animals have again in their construction certain other periodical
functions, which have a reference to alternations of light and
darkness; the length of the period of such functions appears to
coincide with the natural day. In like manner the other arbitrary
magnitudes which enter into the laws of gravity, of the effects of
air and moisture, and of other causes of permanence, and of change,
by which the influences of the elements operate, are the same
arbitrary magnitudes to which the members of the organic world are
adapted by the various peculiarities of their construction.
The illustration of this view will be pursued in the succeeding
chapters; and when the coincidence here spoken of is distinctly
brought before the reader, it will, we trust, be found to convey
the conviction of a wise and benevolent design, which has been
exercised in producing such an agreement between the internal
constitution and the external circumstances of organized beings.
We shall adduce cases where there is an apparent relation between
the course of operation of the elements and the course of vital
functions; between some fixed measure of time or space, traced
in the lifeless and in the living world; where creatures are
constructed on a certain plan, or a certain scale, and this plan
or this scale is exactly the single one which is suited to their
place on the earth; where it was necessary for the Creator (if we
may use such a mode of speaking) _to take account_ of the weight
of the earth, or the density of the air, or the measure of the
ocean, and where these quantities are rightly taken account of in
the arrangements of creation. In such cases we conceive that we
trace a Creator, who, in producing one part of his work, was not
forgetful or careless of another part; who did not cast his living
creatures into the world to prosper or perish as they might find it
suited to them or not; but fitted together, with the nicest skill,
the world and the constitution which he gave to its inhabitants;
so fashioning it and them, that light and darkness, sun and air,
moist and dry, should become their ministers and benefactors, the
unwearied and unfailing causes of their well-being.
We have spoken of the mutual adaptation of the organic and the
inorganic world. If we were to conceive the contrivance of the
world as taking place in an order of time in the contriving mind,
we might also have to conceive this adaptation as taking place
in one of two ways: we might either suppose the laws of inert
nature to be accommodated to the foreseen wants of living things,
or the organization of life to be accommodated to the previously
established laws of nature. But we are not forced upon any such
mode of conception, or upon any decision between such suppositions:
since, for the purpose of our argument, the consequence of either
view is the same. There is an adaptation somewhere or other,
on either supposition. There is account taken of one part of
the system in framing the other: and the mind which took such
account can be no other than that of the Intelligent Author of the
universe. When indeed we come to see the vast number, the variety,
the extent, the interweaving, the reconciling of such adaptations,
we shall readily allow, that all things are so moulded upon and
locked into each other, connected by such subtilty and profundity
of design, that we may well abandon the idle attempt to trace the
_order_ of thought in the mind of the Supreme Ordainer.
CHAPTER I.
_The Length of the Year._
A year is the most important and obvious of the periods which occur
in the organic, and especially in the vegetable world. In this
interval of time the cycle of most of the external influences which
operate upon plants is completed. There is also in plants a cycle
of internal functions, corresponding to this succession of external
causes. The length of either of these periods might have been
different from what it is, according to any grounds of necessity
which we can perceive. But a certain length is selected in both
instances, and in both instances the same. The length of the year
is so determined as to be adapted to the constitution of most
vegetables; or the construction of vegetables is so adjusted as to
be suited to the length which the year really has, and unsuited
to a duration longer or shorter by any considerable portion. The
vegetable clock-work is so set as to go for a year.
The length of the year or interval of recurrence of the seasons is
determined by the time which the earth employs in performing its
revolution round the sun: and we can very easily conceive the solar
system so adjusted that the year should be longer or shorter than
it actually is. We can imagine the earth to revolve round the sun
at a distance greater or less than that which it at present has,
all the forces of the system remaining unaltered. If the earth were
removed towards the centre by about one-eighth of its distance, the
year would be diminished by about a month; and in the same manner
it would be increased by a month on increasing the distance by
one-eighth. We can suppose the earth at a distance of eighty-four
or a hundred and eight millions of miles, just as easily as at its
present distance of ninety-six millions: we can suppose the earth
with its present stock of animals and vegetables placed where Mars
or where Venus is, and revolving in an orbit like one of theirs: on
the former supposition our year would become twenty-three, on the
latter seven of our present months. Or we can conceive the present
distances of the parts of the system to continue what they are,
and the size, or the density of the central mass, the sun, to be
increased or diminished in any proportion; and in this way the time
of the earth’s revolution might have been increased or diminished
in any degree; a greater velocity, and consequently a diminished
period, being requisite in order to balance an augmented central
attraction. In any of these ways the length of the earth’s natural
year might have been different from what it now is: in the last
way without any necessary alteration, so far as we can see, of
temperature.
Now, if any change of this kind were to take place, the working
of the botanical world would be thrown into utter disorder, the
functions of plants would be entirely deranged, and the whole
vegetable kingdom involved in instant decay and rapid extinction.
That this would be the case, may be collected from innumerable
indications. Most of our fruit trees, for example, require the year
to be of its present length. If the summer and the autumn were
much shorter, the fruit could not ripen; if these seasons were
much longer, the tree would put forth a fresh suit of blossoms, to
be cut down by the winter. Or if the year were twice its present
length, a second crop of fruit would probably not be matured, for
want, among other things, of an intermediate season of rest and
consolidation, such as the winter is. Our forest trees in like
manner appear to need all the seasons of our present year for their
perfection; the spring, summer, and autumn, for the developement of
their leaves and consequent formation of their _proper juice_, and
of wood from this; and the winter for the hardening and solidifying
the substance thus formed.
Most plants, indeed, have some peculiar function adapted to each
period of the year, that is of the now existing year. The sap
ascends with extraordinary copiousness at two seasons, in the
spring and in the autumn, especially the former. The opening of
the leaves and the opening of the flowers of the same plants are
so constant to their times, (their _appointed_ times, as we are
naturally led to call them,) that such occurrences might be taken
as indications of the times of the year. It has been proposed in
this way to select a series of botanical facts which should form a
calendar; and this has been termed a _calendar of Flora_. Thus, if
we consider the time of putting forth leaves,[1] the honeysuckle
protrudes them in the month of January; the gooseberry, currant,
and elder in the end of February, or beginning of March; the
willow, elm, and lime-tree in April; the oak and ash, which are
always the latest among trees, in the beginning or towards the
middle of May. In the same manner the flowering has its regular
time: the mezereon and snowdrop push forth their flowers in
February; the primrose in the month of March; the cowslip in April;
the great mass of plants in May and June; many in July, August,
and September; some, not till the month of October, as the meadow
saffron; and some not till the approach and arrival of winter, as
the laurustinus and arbutus.
The fact which we have here to notice, is the recurrence of these
stages in the developement of plants, at intervals precisely or
very nearly of twelve months. Undoubtedly, this result is in part
occasioned by the action of external stimulants upon the plant,
especially heat, and by the recurrence of the intensity of such
agents. Accordingly, there are slight differences in the times of
such occurrences, according to the backwardness or forwardness of
the season, and according as the climate is genial or otherwise.
Gardeners use artifices which will, to a certain extent, accelerate
or retard the time of developement of a plant. But there are
various circumstances which show that this recurrence of the same
events and equal intervals is not entirely owing to external
causes, and that it depends also upon something in the internal
structure of vegetables. Alpine plants do not wait for the stimulus
of the sun’s heat, but exert such a struggle to blossom, that their
flowers are seen among the yet unmelted snow. And this is still
more remarkable in the naturalization of plants from one hemisphere
to the other. When we transplant our fruit trees to the temperate
regions south of the equator, they continue for some years to
flourish at the period which corresponds to our spring. The reverse
of this obtains, with certain trees of the southern hemisphere.
Plants from the Cape of Good Hope, and from Australia, countries
whose summer is simultaneous with our winter, exhibit their
flowers in the coldest part of the year, as the heaths.
This view of the subject agrees with that maintained by the best
botanical writers. Thus Decandolle observes that after making
allowance for all meteorological causes, which determine the epoch
of flowering, we must reckon as another cause the peculiar nature
of each species. The flowering once determined, appears to be
subject to a law of _periodicity_ and habit.[2]
It appears then that the functions of plants have by their nature a
periodical character; and the length of the period thus belonging
to vegetables is a result of their organization. Warmth and light,
soil and moisture, may in some degree modify, and hasten or retard
the stages of this period; but when the constraint is removed
the natural period is again resumed. Such stimulants as we have
mentioned are not the _causes_ of this periodicity. They do not
produce the varied functions of the plant, and could not occasion
their performance at regular intervals, except the plant possessed
a suitable construction. They could not alter the length of the
cycle of vegetable functions, except within certain very narrow
limits. The processes of the rising of the sap, of the formation of
proper juices, of the unfolding of leaves, the opening of flowers,
the fecundation of the fruit, the ripening of the seed, its proper
deposition in order for the reproduction of a new plant;--all these
operations require a certain portion of time, and could not be
compressed into a space less than a year, or at least could not be
abbreviated in any very great degree. And on the other hand, if the
winter were greatly longer than it now is, many seeds would not
germinate at the return of spring. Seeds which have been kept too
long require stimulants to make them fertile.
If therefore the duration of the seasons were much to change,
the processes of vegetable life would be interrupted, deranged,
distempered. What, for instance, would become of our calendar of
Flora, if the year were lengthened or shortened by six months? Some
of the dates would never arrive in the one case, and the vegetable
processes which mark them would be superseded; some seasons would
be without dates in the other case, and these periods would be
employed in a way harmful to the plants, and no doubt speedily
destructive. We should have not only _a year of confusion_, but, if
it were repeated and continued, a year of death.
But in the existing state of things, the duration of the earth’s
revolution round the sun, and the duration of the revolution of the
vegetable functions of most plants are equal. These two periods are
_adjusted_ to each other. The stimulants which the elements apply
come at such intervals and continue for such times, that the plant
is supported in health and vigour, and enabled to reproduce its
kind. Just such a portion of time is measured out for the vegetable
powers to execute their task, as enables them to do so in the best
manner.
Now such an adjustment must surely be accepted as a proof of
design, exercised in the formation of the world. Why should the
solar year be so long and no longer? or, this being of such a
length, why should the vegetable cycle be exactly of the same
length? Can this be chance? And this occurs, it is to be observed,
not in one, or in a few species of plants, but in thousands. Take a
small portion only of known species, as the most obviously endowed
with this adjustment, and say ten thousand. How should all these
organized bodies be constructed for the same period of a year? How
should all these machines be wound up so as to go for the same
time? Even allowing that they could bear a year of a month longer
or shorter, how do they all come within such limits? No chance
could produce such a result. And if not by chance, how otherwise
could such a coincidence occur, than by an intentional adjustment
of these two things to one another? by a selection of such an
organization in plants, as would fit them to the earth on which
they were to grow; by an adaptation of construction to conditions;
of the scale of the construction to the scale of the conditions.
It cannot be accepted as an explanation of this fact in the
economy of plants, that it is necessary to their existence; that
no plants could possibly have subsisted, and come down to us,
except those which were thus suited to their place on earth.
This is true; but this does not at all remove the necessity of
recurring to design as the origin of the construction by which
the existence and continuance of plants is made possible. A watch
could not go, except there were the most exact adjustment in the
forms and positions of its wheels; yet no one would accept it as
an explanation of the origin of such forms and positions, that
the watch would not go if these were other than they are. If the
objector were to suppose that plants were originally fitted to
years of various lengths, and that such only have survived to the
present time, as had a cycle of a length equal to our present
year, or one which could be accommodated to it; we should reply,
that the assumption is too gratuitous and extravagant to require
much consideration; but that, moreover, it does not remove the
difficulty. How came the functions of plants to be _periodical_ at
all? Here is, in the first instance, an agreement in the form of
the laws that prevail in the organic and in the inorganic world,
which appears to us a clear evidence of design in their Author.
And the same kind of reply might be made to any similar objection
to our argument. Any supposition that the universe has gradually
approximated to that state of harmony among the operations of its
different parts, of which we have one instance in the coincidence
now under consideration, would make it necessary for the objector
to assume a previous state of things preparatory to this perfect
correspondence. And in this preparatory condition we should still
be able to trace the rudiments of that harmony, for which it was
proposed to account: so that even the most unbounded license of
hypothesis would not enable the opponent to obliterate the traces
of an intentional adaptation of one part of nature to another.
Nor would it at all affect the argument, if these periodical
occurrences could be traced to some proximate cause: if for
instance it could be shown, that the budding or flowering of
plants is brought about at particular intervals, by the nutriment
accumulated in their vessels during the preceding months. For the
question would still remain, how their functions were so adjusted,
that the accumulation of the nutriment necessary for budding and
flowering, together with the operation itself, comes to occupy
exactly a year, instead of a month only, or ten years. There must
be in their structure some reference to time: how did such a
reference occur? how was it i determined to the particular time of
the earth’s revolution round the sun? This could be no otherwise,
as we conceive, than by design and appointment.
We are left therefore with this manifest adjustment before us, of
two parts of the universe, at first sight so remote; the dimensions
of the solar system and the powers of vegetable life. These two
things are so related, that one has been made to fit the other. The
relation is as clear as that of a watch to a sundial. If a person
were to compare the watch with the dial, hour after hour, and day
after day, it would be impossible for him not to believe that the
watch had been _contrived_ to accommodate itself to the solar day.
We have at least ten thousand kinds of vegetable watches of the
most various forms, which are all accommodated to the solar year;
and the evidence of contrivance seems to be no more capable of
being eluded in this case than in the other.
The same kind of argument might be applied to the animal creation.
The pairing, nesting, hatching, fledging, and flight of birds,
for instance, occupy each its peculiar time of the year; and,
together with a proper period of rest, fill up the twelve months.
The transformations of most insects have a similar reference to the
seasons, their progress and duration. “In every species,” (except
man,) says a writer[3] on animals, “there is a peculiar period of
the year in which the reproductive system exercises its energies.
And the season of love and the period of gestation are so arranged
that the young ones are produced at the time wherein the conditions
of temperature are most suited to the commencement of life.” It is
not our business here to consider the details of such provisions,
beautiful and striking as they are. But the prevalence of the great
law of periodicity in the vital functions of organized beings
will be allowed to have a claim to be considered in its reference
to astronomy, when it is seen that their periodical constitution
derives its use from the periodical nature of the motions of the
planets round the sun; and that the duration of such cycles in the
existence of plants and animals has a reference to the arbitrary
elements of the solar system: a reference which, we maintain, is
inexplicable and unintelligible, except by admitting into our
conceptions; an Intelligent Author, alike of the organic and
inorganic universe.
CHAPTER II.
_The Length of the Day._
We shall now consider another astronomical element, the time of
the revolution of the earth on its axis; and we shall find here
also that the structure of organized bodies are suited to this
element;--that the cosmical and physiological arrangements are
adapted to each other.
We can very easily conceive the earth to revolve on her axis faster
or slower than she does, and thus the days to be longer or shorter
than they are, without supposing any other change to take place.
There is no apparent reason why this globe should turn on its axis
just three hundred and sixty-six times while it describes its orbit
round the sun. The revolutions of the other planets, so far as
we know them, do not appear to follow any rule by which they are
connected with the distance from the sun. Mercury, Venus, and Mars
have days nearly the length of ours. Jupiter and Saturn revolve
in about ten hours each. For any thing we can discover, the earth
might have revolved in this or any other smaller period; or we
might have had, without mechanical inconvenience, much longer days
than we have.
But the terrestrial day, and consequently the length of the cycle
of light and darkness, being what it is, we find various parts
of the constitution both of animals and vegetables, which have
a periodical character in their functions, corresponding to the
diurnal succession of external conditions; and we find that the
length of the period, as it exists in their constitution, coincides
with the length of the natural day.
The alternation of processes which takes place in plants by day
and by night is less obvious, and less obviously essential to
their well-being, than the annual series of changes. But there are
abundance of facts which serve to show that such an alternation is
part of the vegetable economy.
In the same manner in which Linnæus proposed a Calendar of Flora,
he also proposed a _Dial of Flora_, or Flower-Clock; and this
was to consist, as will readily be supposed, of plants, which
mark certain hours of the day, by opening and shutting their
flowers. Thus the day-lily (_hemerocallis fulva_) opens at five
in the morning; the _leontodon taraxacum_, or common dandelion,
at five or six; the _hieracium latifolium_ (hawkweed), at seven;
the _hieracium pilosella_, at eight; the _calendula arvensis_, or
marigold, at nine; the _mesembryanthemum neapolitanum_, at ten or
eleven; and the closing of these and other flowers in the latter
part of the day offers a similar system of hour marks.
Some of these plants are thus expanded in consequence of the
stimulating action of the light and heat of the day, as appears by
their changing their time, when these influences are changed; but
others appear to be constant to the same hours, and independent
of the impulse of such external circumstances. Other flowers by
their opening and shutting prognosticate the weather. Plants of
the latter kind are called by Linnæus _meteoric_ flowers, as
being regulated by atmospheric causes: those which change their
hour of opening and shutting with the length of the day, he terms
_tropical_; and the hours which they measure are, he observes, like
Turkish hours, of varying length at different seasons. But there
are other plants which he terms _equinoctial_; their vegetable
days, like the days of the equator, being always of equal length;
and these open, and generally close, at a fixed and positive
hour of the day. Such plants clearly prove that the periodical
character, and the period of the motions above described, do not
depend altogether on external circumstances.
Some curious experiments on this subject were made by Decandolle.
He kept certain plants in two cellars, one warmed by a stove
and dark, the other lighted by lamps. On some of the plants the
artificial light appeared to have no influence, (_convolvulus
arvensis_, _convolvulus cneorum_, _silene fruticosa_) and they
still followed the clock hours in their opening and closing. The
night-blowing plants appeared somewhat disturbed, both by perpetual
light and perpetual darkness. In either condition they accelerated
their _going_ so much, that in three days they had gained half a
day, and thus exchanged night for day as their time of opening.
Other flowers _went slower_ in the artificial light (_convolvulus
purpureus_.) In like manner those plants which fold and unfold
their leaves were variously affected by this mode of treatment.
The _oxalis stricta_ and _oxalis incarnata_ kept their habits,
without regarding either artificial light or heat. The _mimosa
leucocephala_ folded and unfolded at the usual times, whether in
light or in darkness, but the folding up was not so complete as
in the open air. The _mimosa pudica_ (sensitive plant,) kept in
darkness during the day time, and illuminated during the night, had
in three days accommodated herself to the artificial state, opening
in the evening, and closing in the morning; restored to the open
air, she recovered her usual habits.
Tropical plants in general, as is remarked by our gardeners, suffer
from the length of our summer daylight; and it has been found
necessary to shade them during a certain part of the day.
It is clear from these facts, that there is a diurnal period
belonging to the constitution of vegetables; though the succession
of functions depends in part on external stimulants, as light and
heat, their periodical character is a result of the structure of
the plant; and this structure is such, that the length of the
period, under the common influences to which plants are exposed,
coincides with the astronomical day. The power of accommodation
which vegetables possess in this respect, is far from being such
as either to leave the existence of this periodical constitution
doubtful, or to entitle us to suppose that the day might be
considerably lengthened or shortened without injury to the
vegetable kingdom.
Here then we have an adaptation between the structure of plants,
and the periodical order of light and darkness which arises from
the earth’s rotation; and the arbitrary quantity, the length of the
cycle of the physiological and of the astronomical fact, is the
same. Can this have occurred any otherwise than by an intentional
adjustment?
Any supposition that the astronomical cycle has occasioned the
physiological one, that the structure of plants has been brought
to be what it is by the action of external causes, or that such
plants as could not accommodate themselves to the existing day have
perished, would be not only an arbitrary and baseless assumption,
but moreover useless for the purposes of explanation which it
professes, as we have noticed of a similar supposition with respect
to the annual cycle. How came plants to have periodicity at all in
those functions which have a relation to light and darkness? This
part of their constitution was suited to organized things which
were to flourish on the earth, and it is accordingly bestowed on
them; it was necessary for this end that the period should be of
a certain length; it is of that length and no other. Surely this
looks like intentional provision.
Animals also have a period in their functions and habits; as in
the habits of waking, sleeping, eating, &c. and their well-being
appears to depend on the coincidence of this period with the
length of the natural day. We see that in the day, as it now is,
all animals find seasons for taking food and repose, which agree
perfectly with their health and comfort. Some animals feed during
the day, as nearly all the ruminating animals and land birds;
others feed only in the twilight, as bats and owls, and are called
_crepuscular;_ while many beasts of prey, aquatic birds, and
others, take their food during the night. Those animals which are
nocturnal feeders are diurnal sleepers, while those which are
crepuscular, sleep partly in the night and partly in the day; but
in all, the complete period of these functions is twenty-four
hours. Man, in like manner, in all nations and ages, takes his
principal rest once in twenty-four hours; and the regularity
of this practice seems most suitable to his health, though the
duration of the time allotted to repose is extremely different
in different cases. So far as we can judge, this period is of a
length beneficial to the human frame, independently of the effect
of external agents. In the voyages recently made into high northern
latitudes, where the sun did not rise for three months, the crews
of the ships were made to adhere, with the utmost punctuality, to
the habit of retiring to rest at nine, and rising a quarter before
six; and they enjoyed, under circumstances apparently the most
trying, a state of salubrity quite remarkable. This shows, that
according to the common constitution of such men, the cycle of
twenty-four hours is very commodious, though not imposed on them by
external circumstances.
The hours of food and repose are capable of such wide modifications
in animals, and above all in man, by the influence of external
stimulants and internal emotions, that it is not easy to
distinguish what portion of the tendency to such alternations
depends on original constitution. Yet no one can doubt that the
inclination to food and sleep is periodical, or can maintain, with
any plausibility, that the period may be lengthened or shortened
without limit. We may be tolerably certain that a constantly
recurring period of forty-eight hours would be too long for one day
of employment and one period of sleep, with our present faculties;
and all, whose bodies and minds are tolerably active, will probably
agree that, independently of habit, a perpetual alternation of
eight hours up and four in bed would employ the human powers less
advantageously and agreeably than an alternation of sixteen and
eight. A creature which could employ the full energies of his body
and mind uninterruptedly for nine months, and then take a single
sleep of three months, would not be a man.
When, therefore, we have subtracted from the daily cycle of the
employments of men and animals, that which is to be set down to
the account of habits acquired, and that which is occasioned by
extraneous causes, there still remains a periodical character;
and a period of a certain length, which coincides with, or at any
rate easily accommodates itself to, the duration of the earth’s
revolution. The physiological analysis of this part of our
constitution is not necessary for our purpose. The succession of
exertion and repose in the muscular system, of excited and dormant
sensibility in the nervous, appear to be fundamentally connected
with the muscular and nervous powers, whatever the nature of these
may be. The necessity of these alternations is one of the measures
of the intensity of those vital energies; and it would seem that
we cannot, without assuming the human powers to be altered,
suppose the intervals of tranquillity which they require to be
much changed. This view agrees with the opinion of some of the
most eminent physiologists. Thus Cabanis[4] notices the periodical
and isochronous character of the desire of sleep, as well as of
other appetites. He states also that sleep is more easy and more
salutary, in proportion as we go to rest and rise every day at the
same hours; and observes that this periodicity seems to have a
reference to the motions of the solar system.
Now how should such a reference be at first established in the
constitution of man, animals, and plants, and transmitted from one
generation of them to another? If we suppose a wise and benevolent
Creator, by whom all the parts of nature were fitted to their uses
and to each other, this is what we might expect and can understand.
On any other supposition such a fact appears altogether incredible
and inconceivable.
CHAPTER III.
_The Mass of the Earth._
We shall now consider the adaptation which may, as we conceive, be
traced in the amount of some of the quantities which determine the
course of events in the organic world; and especially in the amount
of the _forces_ which are in action. The life of vegetables and
animals implies a constant motion of their fluid parts, and this
motion must be produced by forces which urge or draw the particles
of the fluids. The positions of the parts of vegetables are also
the result of the flexibility and elasticity of their substance;
the voluntary motions of animals are produced by the tension of the
muscles. But in all those cases, the effect really produced depends
upon the force of gravity also; and in order that the motions and
positions may be such as answer their purpose, the forces which
produce them must have a due proportion to the force of gravity.
In human works, if, for instance, we have a fluid to raise, or
a weight to move, some calculation is requisite, in order to
determine the power which we must use, relatively to the work which
is to be done: we have a mechanical problem to solve, in order that
we may adjust the one to the other. And the same adjustment, the
same result of a comparison of quantities, manifests itself in the
relation which the forces of the organic world bear to the force of
gravity.
The force of gravity might, so far as we can judge, have been
different from what it now is. It depends upon the mass of the
earth; and this mass is one of the elements of the solar system,
which is not determined by any cosmical necessity of which we are
aware. The masses of the several planets are very different, and
do not appear to follow any determinate rule, except that upon
the whole those nearer to the sun appear to be smaller, and those
nearer the outskirts of the system to be larger. We cannot see any
thing which would have prevented either the size or the density of
the earth from being different, to a very great extent, from what
they are.
Now, it will be very obvious that if the intensity of gravity
were to be much increased, or much diminished, if every object
were to become twice as heavy or only half as heavy as it now is,
all the forces, both of involuntary and voluntary motion which
produce the present orderly and suitable results by being properly
proportioned to the resistance which they experience, would be
thrown off their balance; they would produce motions too quick or
too slow, wrong positions, jerks and stops, instead of steady,
well conducted movements. The universe would be like a machine ill
regulated; every thing would go wrong; repeated collisions and a
rapid disorganization must be the consequence. We will, however,
attempt to illustrate one or two of the cases in which this would
take place, by pointing out forces which act in the organic world,
and which are adjusted to the force of gravity.
1. The first instance we shall take, is the force manifested by
the ascent of the sap in vegetables. It appears by a multitude
of indisputable experiments, (among the rest, those of Hales,
Mirbel, and Dutrochet,) that all plants imbibe moisture by their
roots, and _pump it up_, by some internal force, into every part
of their frame, distributing it into every leaf. It will be easily
conceived that this operation must require a very considerable
mechanical force; for the fluid must be sustained as if it were a
single column reaching to the top of the tree. The division into
minute parts and distribution through small vessels does not at all
diminish the total force requisite to raise it. If, for instance,
the tree be thirty-three feet high, the pressure must be fifteen
pounds upon every square inch in the section of the vessels of
the bottom in order merely to support the sap. And it is not only
supported, but propelled upwards with great force, so as to supply
the constant evaporation of the leaves. The pumping power of the
tree must, therefore, be very considerable.
That this power is great, has been confirmed by various curious
experiments, especially by those of Hales. He measured the force
with which the stems and branches of trees draw the fluid from
below, and push it upwards. He found, for instance, that a vine in
the _bleeding_ season could push up its sap in a glass tube to the
height of twenty-one feet above the stump of an amputated branch.
The force which produces this effect is part of the economy of the
vegetable world; and it is clear that the due operation of the
force depends upon its being rightly proportioned to the force of
gravity. The weight of the fluid must be counterbalanced, and an
excess of force must exist to produce the motion upwards. In the
common course of vegetable life, the rate of ascent of the sap is
regulated, on the one hand, by the upward pressure of the vegetable
power, and on the other, by the amount of the gravity of the fluid,
along with the other resistances, which are to be overcome. If,
therefore, we suppose gravity to increase, the rapidity of this
vegetable circulation will diminish, and the rate at which this
function proceeds, will not correspond either to the course of the
seasons, or the other physiological processes with which this has
to co-operate. We might easily conceive such an increase of gravity
as would stop the vital movements of the plant in a very short
time. In like manner, a diminution of the gravity of the vegetable
juices would accelerate the rising of the sap, and would, probably,
hurry and overload the leaves and other organs, so as to interfere
with their due operation. Some injurious change, at least, would
take place.
Here, then, we have the forces of the minutest parts of vegetables
adjusted to the magnitude of the whole mass of the earth on which
they exist. There is no apparent connexion between the quantity of
matter of the earth, and the force of imbibition of the roots of a
vine, or the force of propulsion of the vessels of its branches.
Yet, these things have such a proportion as the well being of the
vine requires. How is this to be accounted for, but by supposing
that the circumstances under which the vine was to grow, were
attended to in devising its structure?
We have not here pretended to decide whether this force of
propulsion of vegetables is mechanical or not, because the argument
is the same for our purpose on either supposition. Some very
curious experiments have recently been made, (by M. Dutrochet,)
which are supposed to show that the force is mechanical; that when
two different fluids are separated by a thin membrane, a force
which M. Dutrochet calls _endosmose_ urges one fluid through the
membrane: and that the roots of plants are provided with small
vesicles which act the part of such a membrane. M. Poisson has
further attempted to show that this force of _endosmose_ may be
considered as a particular modification of capillary action. If
these views be true, we have here two mechanical forces, capillary
action and gravity, which are adjusted to each other in the manner
precisely suited to the welfare of vegetables.
2. As another instance of adaptation between the force of gravity
and forces which exist in the vegetable world, we may take the
positions of flowers. Some flowers grow with the hollow of their
cup upwards: others “hang the pensive head,” and turn the opening
downwards. Now of these “nodding flowers,” as Linnæus calls
them, he observes that they are such as have their pistil longer
than the stamens; and, in consequence of this position, the dust
from the anthers which are at the ends of the stamens can fall
upon the stigma or extremity of the pistil; which process is
requisite for making the flower fertile. He gives as instances the
flowers _campanula_, _leucoium_, _galanthus_, _fritillaria_. Other
botanists have remarked that the position changes at different
periods of the flower’s progress. The pistil of the Euphorbia
(which is a little globe or germen on a slender stalk) grows
upright at first, and is taller than the stamens: at the period
suited to its fecundation, the stalk bends under the weight of
the ball at its extremity, so as to depress the germen below the
stamens; after this it again becomes erect, the globe being now a
fruit filled with fertile seeds.
The positions in all these cases depend upon the length and
flexibility of the stalk which supports the flower, or in the
case of the Euphorbia, the germen. It is clear that a very slight
alteration in the force of gravity, or in the stiffness of the
stalk, would entirely alter the position of the flower cup, and
thus make the continuation of the species impossible. We have
therefore here a little mechanical contrivance, which would have
been frustrated if the proper intensity of gravity had not been
assumed in the reckoning. An earth greater or smaller, denser or
rarer than the one on which we live, would require a change in the
structure and strength of the footstalks of all the little flowers
that hang their heads under our hedges. There is something curious
in thus considering the whole mass of the earth from pole to pole,
and from circumference to centre, as employed in keeping a snowdrop
in the position most suited to the promotion of its vegetable
health.
It would be easy to mention many other parts of the economy of
vegetable life, which depend for their use on their adaptation to
the force of gravity. Such are the forces and conditions which
determine the positions of leaves and of branches. Such again
those parts of the vegetable constitution which have reference to
the pressure of the atmosphere; for differences in this pressure
appear to exercise a powerful influence on the functions of plants,
and to require differences of structure. But we pass over these
considerations. The slightest attention to the relations of natural
objects will show that the subject is inexhaustible; and all that
we can or need do is to give a few examples, such as may show the
nature of the impression which the examination of the universe
produces.
3. Another instance of the adjustment of organic structure to the
force of gravity may be pointed out in the muscular powers of
animals. If the force of gravity were increased in any considerable
proportion at the surface of the earth, it is manifest that all
the swiftness, and strength, and grace of animal motions must
disappear. If, for instance, the earth were as large as Jupiter,
gravity would be eleven times what it is, the lightness of the
fawn, the speed of the hare, the spring of the tiger, could no
longer exist with the existing muscular powers of those animals;
for man to lift himself upright, or to crawl from place to place,
would be a labour slower and more painful than the motions of the
sloth. The density and pressure of the air too would be increased
to an intolerable extent, and the operation of respiration, and
others, which depend upon these mechanical properties, would be
rendered laborious, ineffectual, and probably impossible.
If, on the other hand, the force of gravity were much lessened,
inconveniences of an opposite kind would occur. The air would be
too thin to breathe; the weight of our bodies, and of all the
substances surrounding us, would become too slight to resist the
perpetually occurring causes of derangement and unsteadiness: we
should feel a want of ballast in our movements.
It has sometimes been maintained by fanciful theorists that the
earth is merely a shell, and that the central parts are hollow.
All the reasons we can collect appear to be in favour of its being
a solid mass, considerably denser than any known rock. If this be
so, and if we suppose the interior to be at any time scooped out,
so as to leave only such a shell as the above mentioned speculators
have asserted, we should not be left in ignorance of the change,
though the appearance of the surface might remain the same. We
should discover the want of the usual force of gravity, by the
instability of all about us. Things would not lie where we placed
them, but would slide away with the slightest push. We should have
a difficulty in standing or walking, something like what we have
on ship-board when the deck is inclined; and we should stagger
helplessly through an atmosphere thinner than that which oppresses
the respiration of the traveller on the tops of the highest
mountains.
We see therefore that those dark and unknown central portions of
the earth, which are placed far beyond the reach of the miner and
the geologist, and of which man will probably never know anything
directly, are not to be considered as quite disconnected with us,
as deposits of useless lumber without effect or purpose. We feel
their influence on every step we take and on every breath we draw;
and the powers we possess, and the comforts we enjoy would be
unprofitable to us, if they had not been prepared with a reference
to those as well as to the near and visible portions of the earth’s
mass.
The arbitrary quantity, therefore, of which we have been treating,
the intensity of the force of gravity, appears to have been taken
account of, in establishing the laws of those forces by which
the processes of vegetable and animal life are carried on. And
this leads us inevitably, we conceive, to the belief of a supreme
contriving mind, by which these laws were thus devised and thus
established.
CHAPTER IV.
_The Magnitude of the Ocean._
There are several arbitrary quantities which contribute to
determine the state of things at the earth’s surface besides those
already mentioned. Some of these we shall briefly refer to, without
pursuing the subject into detail. We wish not only to show that
the properties and processes of vegetable and animal life must
be adjusted to each of these quantities in particular, but also
to point out how numerous and complicated the conditions of the
existence of organized beings are; and we shall thus be led to
think less inadequately of the intelligence which has embraced at
once, and combined without confusion, all these conditions. We
appear thus to be conducted to the conviction not only of design
and intention, but of supreme knowledge and wisdom.
One of the quantities which enters into the constitution of the
terrestrial system of things is the bulk of the waters of the
ocean. The mean depth of the sea, according to the calculations of
Laplace, is four or five miles. On this supposition, the addition
to the sea of one-fourth of the existing waters would drown the
whole of the globe, except a few chains of mountains. Whether this
be exact or no, we can easily conceive the quantity of water which
lies in the cavities of our globe to be greater or less than it
at present is. With every such addition or subtraction the form
and magnitude of the dry land would vary, and if this change were
considerable, many of the present relations of things would be
altered. It may be sufficient to mention one effect of such a
change. The sources which water the earth, both clouds, rains,
and rivers, are mainly fed by the aqueous vapour raised from the
sea; and therefore if the sea were much diminished, and the land
increased, the mean quantity of moisture distributed upon the land
must be diminished, and the character of climates, as to wet and
dry, must be materially affected. Similar, but opposite changes
would result from the increase of the surface of the ocean.
It appears then that the magnitude of the ocean is one of the
conditions to which the structure of all organized beings which are
dependent upon climate must be adapted.
CHAPTER V.
_The Magnitude of the Atmosphere._
The total quantity of air of which our atmosphere is composed is
another of the arbitrary magnitudes of our terrestrial system; and
we may apply to this subject considerations similar to those of the
last section. We can see no reason why the atmosphere might not
have been larger in comparison to the globe which it surrounds;
those of Mars and Jupiter appear to be so. But if the quantity of
air were increased, the structure of organized beings would in many
ways cease to be adapted to their place. The atmospheric pressure,
for instance, would be increased, which, as we have already
noticed, would require an alteration in the structure of vegetables.
Another way in which an increase of the mass of the atmosphere
would produce inconvenience would be in the force of winds. If the
current of air in a strong gale were doubled or tripled, as might
be the case if the atmosphere were augmented, the destructive
effects would be more than doubled or tripled. With such a change,
nothing could stand against a storm. In general, houses and trees
resist the violence of the wind; and except in extreme cases, as
for instance in occasional hurricanes in the West Indies, a few
large trees in a forest are unusual trophies of the power of the
tempest. The breezes which we commonly have are harmless messengers
to bring about the salutary changes of the atmosphere, even the
motion which they communicate to vegetables tends to promote their
growth, and is so advantageous, that it has been proposed to
imitate it by artificial breezes in the hothouse. But with a stream
of wind blowing against them, like three, or five, or ten, gales
compressed into the space of one, none of the existing trees could
stand; and except they could either bend like rushes in a stream,
or extend their roots far wider than their branches, they must be
torn up in whole groves. We have thus a manifest adaptation of the
present usual strength of the materials and of the workmanship of
the world to the stress of wind and weather which they have to
sustain.
CHAPTER VI.
_The Constancy and Variety of Climates._
It is possible to conceive arrangements of our system, according
to which all parts of the earth might have the same, or nearly
the same, climate. If, for example, we suppose the earth to be a
flat disk, or flat ring, like the ring of Saturn, revolving in its
own plane as that does, each part of both the flat surfaces would
have the same exposure to the sun, and the same temperature, so
far as the sun’s effect is concerned. There is no obvious reason
why a planet of such a form might not be occupied by animals and
vegetables, as well as our present earth; and on this supposition
the climate would be every where the same, and the whole surface
might be covered with life, without the necessity of there being
any difference in the kind of inhabitants belonging to different
parts.
Again, it is possible to conceive arrangements according to which
no part of our planet should have any steady climate. This may
probably be the case with a comet. If we suppose such a body,
revolving round the sun in a very oblong ellipse, to be of small
size and of a very high temperature, and therefore to cool rapidly;
and if we suppose it also to be surrounded by a large atmosphere,
composed of various gases; there would, on the surface of such a
body, be no average climate or seasons for each place. The years,
if we give this name to the intervals of time occupied by its
successive revolutions, would be entirely unlike one another. The
greatest heat of one year might be cool compared with the greatest
cold of a preceding one. The greatest heats and colds might succeed
each other at intervals perpetually unequal. The atmosphere might
be perpetually changing its composition by the condensation of
some of its constituent gases. In the operations of the elements,
all would be incessant and rapid change, without recurrence or
compensation. We cannot say that organized beings could not be
fitted for such a habitation; but if they were, the adaptation must
be made by means of a constitution quite different from that of
almost all organized beings known to us.
The state of things upon the earth, in its present condition, is
very different from both these suppositions. The climate of the
same place, notwithstanding perpetual and apparently irregular
change, possesses a remarkable steadiness. And, though in different
places the annual succession of appearances in the earth and
heavens, is, in some of its main characters, the same, the result
of these influences in the average climate is very different.
Now, to this remarkable constitution of the earth as to climate,
the constitution of the animal and vegetable world is precisely
adapted. The differences of different climates are provided for by
the existence of entirely different classes of plants and animals
in different countries. The constancy of climate at the same place
is a necessary condition of the prosperity of each species there
fixed.
We shall illustrate, by a few details, these characteristics in the
constitution of inorganic and of organic nature, with the view of
fixing the reader’s attention upon the correspondence of the two.
1. The succession and alternation, at any given place, of heat
and cold, rain and sunshine, wind and calm, and other atmospheric
changes, appears at first sight to be extremely irregular, and not
subject to any law. It is, however, easy to see, with a little
attention, that there is a certain degree of constancy in the
average weather and seasons of each place, though the particular
facts of which these generalities are made up seem to be out of the
reach of fixed laws. And when we apply any numerical measure to
these particular occurrences, and take the average of the numbers
thus observed, we generally find a remarkably close correspondence
in the numbers belonging to the whole, or to analogous portions of
successive years. This will be found to apply to the measures given
by the thermometer, the barometer, the hygrometer, the rain gauge,
and similar instruments. Thus it is found that very hot summers,
or very cold winters, raise or depress the mean annual temperature
very little above or below the general standard.
The heat may be expressed by degrees of the thermometer; the
temperature of the day is estimated by this measure taken at
a certain period of the day, which is found by experience to
correspond with the daily average; and the mean annual temperature
will then be the average of all the heights of the thermometer for
every day in the year.
The mean annual temperature of London, thus measured, is about
50 degrees 4-10ths. The frost of the year 1788 was so severe that
the Thames was passable on the ice; the mean temperature of that
year was 50 degrees 6-10ths, being within a small fraction a degree
of the standard. In 1796, when the greatest cold ever observed in
London occurred, the mean temperature of the year was 50 degrees
1-10th, which is likewise within a fraction of a degree of the
standard. In the severe winter of 1813-14, when the Thames, Tyne,
and other large rivers in England were completely frozen over, the
mean temperature of the two years was 49 degrees, being little more
than a degree below the standard. And in the year 1808, when the
summer was so hot that the temperature in London was as high as 93½
degrees, the mean heat of the year was 50½, which is about that of
the standard.
The same numerical indications of the constancy of climate at the
same place might be collected from the records of other instruments
of the kind above-mentioned.
We shall, hereafter, consider some of the very complex agencies by
which this steadiness is produced; and shall endeavour to point
out intentional adaptations to this object. But we may, in the
meantime, observe how this property of the atmospheric changes is
made subservient to a further object.
To this constancy of the climates of each place, the structure
of plants is adapted; almost all vegetables require a particular
mean temperature of the year, or of some season of the year; a
particular degree of moisture, and similar conditions. This will
be seen by observing that the range of most plants as to climate
is very limited. A vegetable which flourishes where the mean
temperature is 55 degrees, would pine and wither when removed to a
region where the average is 50 degrees. If, therefore, the average
at each place were to vary as much as this, our plants with their
present constitutions would suffer, languish, and soon die.
2. It will be readily understood that the same mode of measurement
by which we learn the constancy of climate at the same place,
serves to show us the variety which belongs to different places.
While the variations of the same region vanish when we take the
averages even of moderate periods, those of distant countries are
fixed and perpetual; and stand out more clear and distinct, the
longer is the interval for which we measure their operation.
In the way of measuring already described, the mean temperature
of Petersburg is 39 degrees, of Rome 60, of Cairo 72. Such
observations as these, and others of the same kind, have been made
at various places, collected and recorded; and in this way the
surface of the earth can be divided by boundary lines into various
strips, according to these physical differences. Thus, the zones
which take in all the places having the same or nearly the same
mean annual temperature, have been called _isothermal_ zones. These
zones run nearly parallel to the equator, but not exactly, for,
in Europe, they bend to the north in going eastward. In the same
manner, the lines passing through all places which have an equal
temperature for the summer or the winter half of the year, have
been called respectively _isotheral_ and _isochimal_ lines. These
do not coincide with the isothermal lines, for a place may have
the same temperature as another, though its summer be hotter and
its winter colder, as is the case of Pekin compared with London.
In the same way we might conceive lines drawn according to the
conditions of clouds, rain, wind, and the like circumstances, if we
had observations enough to enable us to lay down such lines. The
course of vegetation depends upon the combined influence of all
such conditions; and the lines which bound the spread of particular
vegetable productions do not, in most cases, coincide with any of
the separate meteorological boundaries above spoken of. Thus, the
northern limit of vineyards runs through France, in a direction
very nearly north-east and south-west, while the line of equal
temperature is nearly east and west. And the spontaneous growth or
advantageous cultivation of other plants, is in like manner bounded
by lines of which the course depends upon very complex causes, but
of which the position is generally precise and fixed.
CHAPTER VII.
_The Variety of Organization corresponding to the Variety of
Climate._
The organization of plants and animals is in different tribes
formed upon schemes more or less different, but in all cases
adjusted in a general way to the course and action of the elements.
The differences are connected with the different habits and manners
of living which belong to different species; and at any one place
the various species, both of animals and plants, have a number of
relations and mutual dependences arising out of these differences.
But besides the differences of this kind, we find in the forms of
organic life another set of differences, by which the animal and
vegetable kingdom are fitted for that variety in the climates of
the earth, which we have been endeavouring to explain.
The existence of such differences is too obvious to require to be
dwelt upon. The plants and animals which flourish and thrive in
countries remote from each other, offer to the eye of the traveller
a series of pictures, which, even to an ignorant and unreflective
spectator, is full of a peculiar and fascinating interest in
consequence of the novelty and strangeness of the successive scenes.
Those who describe the countries between the tropics, speak with
admiration of the luxuriant profusion and rich variety of the
vegetable productions of those regions. Vegetable life seems there
far more vigorous and active, the circumstances under which it goes
on, far more favourable than in our latitudes. Now if we conceive
an inhabitant of those regions, knowing, from the circumstances
of the earth’s form and motion, the difference of climates which
must prevail upon it, to guess, from what he saw about him, the
condition of other parts of the globe as to vegetable wealth, is
not likely that he would suppose that the extra-tropical climates
must be almost devoid of plants? We know that the ancients, living
in the temperate zone, came to the conclusion that both the torrid
and the frigid zones must be uninhabitable. In like manner the
equatorial reasoner would probably conceive that vegetation must
cease, or gradually die away, as he should proceed to places
further and further removed from the genial influence of the sun.
The mean temperature of his year being about 80 degrees, he would
hardly suppose that any plants could subsist through a year, where
the mean temperature was only 50, where the temperature of the
summer quarter was only 64, and where the mean temperature of a
whole quarter of the year was a very few degrees removed from that
at which water becomes solid. He would suppose that scarcely any
tree, shrub, or flower could exist in such a state of things, and
so far as the plants of his own country are concerned, he would
judge rightly.
But the countries further removed from the equator are not left
thus unprovided. Instead of being scantily occupied by such of the
tropical plants as could support a stunted and precarious life
in ungenial climes, they are abundantly stocked with a multitude
of vegetables which appear to be constructed expressly for them,
inasmuch as these species can no more flourish at the equator than
the equatorial species can in these temperate regions. And such
new supplies thus adapted to new conditions, recur perpetually
as we advance towards the apparently frozen and untenantable
regions in the neighbourhood of the pole. Every zone has its
peculiar vegetables; and as we miss some, we find others make their
appearance, as if to replace those which are absent.
If we look at the indigenous plants of Asia and Europe, we find
such a succession as we have here spoken of. At the equator we
find the natives of the Spice Islands, the clove and nutmeg trees,
pepper and mace. Cinnamon bushes clothe the surface of Ceylon; the
odoriferous sandal wood, the ebony tree, the teak tree, the banyan,
grow in the East Indies. In the same latitudes in Arabia the Happy
we find balm, frankincense and myrrh, the coffee tree, and the
tamarind. But in these countries, at least in the plains, the trees
and shrubs which decorate our more northerly climes are wanting.
And as we go northwards, at every step we change the vegetable
group, both by addition and by subtraction. In the thickets to the
west of the Caspian Sea we have the apricot, citron, peach, walnut.
In the same latitude in Spain, Sicily, and Italy, we find the
dwarf palm, the cypress, the chestnut, the cork tree: the orange
and lemon tree perfume the air with their blossoms; the myrtle
and pomegranate grow wild among the rocks. We cross the Alps, and
we find the vegetation which belongs to northern Europe, of which
England is an instance. The oak, the beech, and the elm are natives
of Great Britain: the elm tree seen in Scotland, and in the north
of England, is the wych elm. As we travel still further to the
north the forests again change their character. In the northern
provinces of the Russian empire are found forests of the various
species of firs: the Scotch and spruce fir, and the larch. In the
Orkney Islands no tree is found but the hazel, which occurs again
on the northern shores of the Baltic. As we proceed into colder
regions we still find species which appear to have been made for
these situations. The hoary or cold elder makes its appearance
north of Stockholm: the sycamore and mountain ash accompany us to
the head of the gulf of Bothnia: and as we leave this and traverse
the Dophrian range, we pass in succession the boundary lines of the
spruce fir, the Scotch fir, and those minute shrubs which botanists
distinguish as the dwarf birch and dwarf willow. Here, near to or
within the arctic circle, we yet find wild flowers of great beauty;
the mezereum, the yellow and white water lily, and the European
globe flower. And when these fail us, the reindeer moss still makes
the country habitable for animals and man.
We have thus a variety in the laws of vegetable organization
remarkably adapted to the variety of climates; and by this
adaptation the globe is clothed with vegetation and peopled with
animals from pole to pole, while without such an adaptation
vegetable and animal life must have been confined almost, or
entirely, to some narrow zone on the earth’s surface. We conceive
that we see here the evidence of a wise and benevolent intention,
overcoming the varying difficulties, or employing the varying
resources of the elements, with an inexhaustible fertility of
contrivance, a constant tendency to diffuse life and well being.
2. One of the great uses to which the vegetable wealth of the earth
is applied, is the support of man, whom it provides with food and
clothing; and the adaptation of tribes of indigenous vegetables
to every climate has, we cannot but believe, a reference to the
intention that the human race should be diffused over the whole
globe. But this end is not answered by indigenous vegetables alone;
and in the variety of vegetables capable of being _cultivated_ with
advantage in various countries, we conceive that we find evidence
of an additional adaptation of the scheme of organic life to the
system of the elements.
The cultivated vegetables, which form the necessaries or luxuries
of human life, are each confined within limits, narrow, when
compared with the whole surface of the earth; yet almost every part
of the earth’s surface is capable of being abundantly covered with
one kind or other of these. When one class fails, another appears
in its place. Thus corn, wine, and oil, have each its boundaries.
Wheat extends through the old Continent, from England to Thibet:
but it stops soon in going northwards, and is not found to succeed
in the west of Scotland. Nor does it thrive better in the torrid
zone than in the polar regions: within the tropics, wheat, barley
and oats are not cultivated, excepting in situations considerably
above the level of the sea: the inhabitants of those countries have
other species of grain, or other food. The cultivation of the vine
succeeds only in countries where the annual temperature is between
50 and 63 degrees. In both hemispheres, the profitable culture
of this plant ceases within 30 degrees of the equator, unless in
elevated situations, or in islands, as Teneriffe. The limits of the
cultivation of maize and of olives in France are parallel to those
which bound the vine and corn in succession to the north. In the
north of Italy, west of Milan, we first meet with the cultivation
of rice; which extends over all the southern part of Asia, wherever
the land can be at pleasure covered with water. In great part of
Africa millet is one of the principal kinds of grain.
Cotton is cultivated to latitude 40 in the new world, but extends
to Astrachan in latitude 46 in the old. The sugar cane, the
plantain, the mulberry, the betel nut, the indigo tree, the tea
tree, repay the labours of the cultivator in India and China;
and several of these plants have been transferred, with success,
to America and the West Indies. In equinoctial America a great
number of inhabitants find abundant nourishment on a narrow space
cultivated with plantain, cassava yams, and maize. The bread fruit
tree begins to be cultivated in the Manillas, and extends through
the Pacific; the sago palm in the Moluccas, the cabbage tree in the
Pelew islands.
In this manner the various tribes of men are provided with
vegetable food. Some however live on their cattle, and thus make
the produce of the earth only mediately subservient to their
wants. Thus the Tartar tribes depend on their flocks and herds for
food: the taste for the flesh of the horse seems to belong to the
Mongols, Fins, and other descendants of the ancient Scythians: the
locust eaters are found now, as formerly, in Africa.
Many of these differences depend upon custom, soil, and other
causes with which we do not here meddle; but many are connected
with climate: and the variety of the resources which man thus
possesses, arises from the variety of constitution belonging to
cultivable vegetables, through which one is fitted to one range of
climate, and another to another. We conceive that this variety and
succession of fitness for cultivation, shows undoubted marks of a
most foreseeing and benevolent design in the Creator of man and of
the world.
3. By differences in vegetables of the kind we have above
described, the sustentation and gratification of man’s physical
nature is copiously provided for. But there is another
circumstance, a result of the difference of the native products of
different regions, and therefore a consequence of that difference
of climate on which the difference of native products depends,[5]
which appears to be worthy our notice. The difference of the
productions of different countries has a bearing not only upon the
physical, but upon the social and moral condition of man.
The intercourse of nations in the way of discovery, colonization,
commerce; the study of the natural history, manners, institutions
of foreign countries; lead to most numerous and important results.
Without dwelling upon this subject, it will probably be allowed
that such intercourse has a great influence upon the comforts, the
prosperity, the arts, the literature, the power, of the nations
which thus communicate. Now the variety of the productions of
different lands supplies both the stimulus to this intercourse, and
the instruments by which it produces its effects. The desire to
possess the objects or the knowledge which foreign countries alone
can supply, urges the trader, the traveller, the discoverer to
compass land and sea; and the progress of the arts and advantages
of civilization consists almost entirely in the cultivation, the
use, the improvement of that which has been received from other
countries.
This is the case to a much greater extent than might at first sight
be supposed. Where man is active as a cultivator, he scarcely ever
bestows much of his care on those vegetables which the land would
produce in a state of nature. He does not select some of the plants
of the soil and improve them by careful culture, but, for the most
part, he expels the native possessors of the land, and introduces
colonies of strangers.
Thus, to take the condition of our own part of the globe as an
example; scarcely one of the plants which occupy our fields and
gardens is indigenous to the country. The walnut and the peach
come to us from Persia; the apricot from Armenia: from Asia
Minor, and Syria, we have the cherry tree, the fig, the pear, the
pomegranate, the olive, the plum, and the mulberry. The vine which
is now cultivated is not a native of Europe; it is found wild on
the shores of the Caspian, in Armenia and Caramania. The most
useful species of plants, the _cereal_ vegetables, are certainly
strangers, though their birth place seems to be an impenetrable
secret. Some have fancied that barley is found wild on the banks
of the Semara, in Tartary, rye in Crete, wheat at Baschkiros, in
Asia; but this is held by the best botanists to be very doubtful.
The potatoe, which has been so widely diffused over the world in
modern times, and has added so much to the resources of life in
many countries, has been found equally difficult to trace back to
its wild condition.
Thus widely are spread the traces of the connexion of the progress
of civilization with national intercourse. In our own country a
higher state of the arts of life is marked by a more ready and
extensive adoption of foreign productions. Our fields are covered
with herbs from Holland, and roots from Germany; with Flemish
farming and Swedish turnips; our hills with forests of the firs of
Norway. The chestnut and poplar of the south of Europe adorn our
lawns, and below them flourish shrubs and flowers from every clime
in profusion. In the mean time Arabia improves our horses, China
our pigs, North America our poultry, Spain our sheep, and almost
every country sends its dog. The products which are ingredients
in our luxuries, and which we cannot naturalize at home, we raise
in our colonies; the cotton, coffee, sugar of the east are thus
transplanted to the farthest west; and man lives in the middle of a
rich and varied abundance which depends on the facility with which
plants and animals and modes of culture can be transferred into
lands far removed from those in which nature had placed them. And
this plenty and variety of material comforts is the companion and
the mark of advantages and improvements in social life, of progress
in art and science, of activity of thought, of energy of purpose,
and of ascendancy of character.
The differences in the productions of different countries which
lead to the habitual intercourse of nations, and through this
to the benefits which we have thus briefly noticed, do not all
depend upon the differences of temperature and climate alone. But
these differences are among the causes, and are some of the most
important causes, or conditions, of the variety of products; and
thus that arrangement of the earth’s form and motion from which
the different climates of different places arises, is connected
with the social and moral welfare and advancement of man.
We conceive that this connexion, though there must be to our
apprehension much that is indefinite and uncertain in tracing
its details, is yet a point where we may perceive the profound
and comprehensive relations established by the counsel and
foresight of a wise and good Creator of the world and of man, by
whom the progress and elevation of the human species was neither
uncontemplated nor uncared for.
4. We have traced, in the variety of organized beings, an
_adaptation_ to the variety of climates, a _provision_ for the
sustentation of man all over the globe, and an _instrument_ for
the promotion of civilization and many attendant benefits. We have
not considered this _variety_ as _itself_ a purpose which we can
perceive or understand without reference to some ulterior end. Many
persons, however, and especially those who are already in the habit
of referring the world to its Creator, will probably see something
admirable in itself in this vast variety of created things.
There is indeed something well fitted to produce and confirm a
reverential wonder, in these apparently inexhaustible stores of
new forms of being and modes of existence; the fixity of the laws
of each class, its distinctness from all others, its relations to
many. Structures and habits and characters are exhibited, which are
connected and distinguished according to every conceivable degree
of subordination and analogy, in their resemblances and in their
differences. Every new country we explore presents us with new
combinations, where the possible cases seem to be exhausted; and
with new resemblances and differences, constructed as if to elude
what conjecture might have hit upon, by proceeding from the old
ones. Most of those who have any large portion of nature brought
under their notice in this point of view, are led to feel that
there is, in such a creation, a harmony, a beauty, and a dignity,
of which the impression is irresistible; which would have been
wanting in any more uniform and limited system such as we might try
to imagine; and which of itself gives to the arrangements by which
such a variety on the earth’s surface is produced, the character of
well devised means to a worthy end.
CHAPTER VIII.
_The Constituents of Climate._
We have spoken of the steady average of the climate at each place,
of the difference of this average at different places, and of the
adaptation of organized beings to this character in the laws of
the elements by which they are affected. But this steadiness in
the general effect of the elements, is the result of an extremely
complex and extensive machinery. Climate, in its wider sense,
is not one single agent, but is the aggregate result of a great
number of different agents, governed by different laws, producing
effects of various kinds. The steadiness of this compound agency is
not the steadiness of a permanent condition, like that of a body
at rest; but it is the steadiness of a state of constant change
and movement, succession and alternation, seeming accident and
irregularity. It is a perpetual repose, combined with a perpetual
motion; an invariable average of most variable quantities. Now, the
manner in which such a state of things is produced, deserves, we
conceive, a closer consideration. It may be useful to show how the
particular laws of the action of each of the elements of climate
are so adjusted that they do not disturb this general constancy.
The principal constituents of climate are the following:--the
temperature of the earth, of the water, of the air:--the
distribution of the aqueous vapour contained in the
atmosphere:--the winds and rains by which the equilibrium of the
atmosphere is restored when it is in any degree disturbed. The
effects of light, of electricity, probably of other causes also,
are no doubt important in the economy of the vegetable world,
but these agencies have not been reduced by scientific inquirers
to such laws as to admit of their being treated with the same
exactness and certainty which we can obtain in the case of those
first mentioned.
We shall proceed to trace some of the peculiarities in the laws of
the different physical agents which are in action at the earth’s
surface, and the manner in which these peculiarities bear upon the
general result.
_The Laws of Heat with respect to the Earth._
One of the main causes which determine the temperature of each
climate is the effect of the sun’s rays on the solid mass of the
earth. The laws of this operation have been recently made out with
considerable exactness, experimentally by Leslie, theoretically by
Fourier, and by other inquirers. The theoretical inquiries have
required the application of very complex and abstruse mathematical
investigations; but the general character of the operation may,
perhaps, be made easily intelligible.
The earth, like all solid bodies, transmits into its interior the
impressions of heat which it receives at the surface; and throws
off the superfluous heat from its surface into the surrounding
space. These processes are called _conduction_ and _radiation_, and
have each their ascertained mathematical laws.
By the laws of conduction, the daily impressions of heat which the
earth receives, follow each other into the interior of the mass,
like the waves which start from the edge of a canal;[6] and like
them, become more and more faint as they proceed, till they melt
into the general level of the internal temperature. The heat thus
transmitted is accumulated in the interior of the earth, as in a
reservoir, and flows from one part to another of this reservoir.
The parts of the earth near the equator are more heated by the
sun than other parts, and on this account there is a perpetual
internal conduction of heat from the equatorial to other parts
of the sphere. And as all parts of the surface throw off heat by
radiation, in the polar regions, where the surface receives little
in return from the sun, a constant waste is produced. There is
thus from the polar parts a perpetual dispersion of heat in the
surrounding space, which is supplied by a perpetual internal flow
from the equator towards each pole.
Here, then, is a kind of circulation of heat; and the quantity and
rapidity of this circulation, determine the quantity of heat in the
solid part of the earth, and in each portion of it; and through
this, the _mean_ temperature belonging to each point on its surface.
If the earth _conducted_ heat more rapidly than it does, the
inequalities of temperature would be more quickly balanced,
and the temperature of the ground (below the reach of annual
and diurnal variations) would differ less than it does. If the
surface _radiated_ more rapidly than it does, the flow of heat
from the polar regions would increase, and the temperature of the
interior of the globe would find a lower level; the differences of
temperature in different latitudes would increase, but the mean
temperature of the globe would diminish.
There is nothing which, so far as we can perceive, determines
necessarily, either the conducting or the radiating power of
the earth to its present value. The measures of such powers, in
different substances, differ very widely. If the earth were a globe
of pure iron, it would conduct heat, probably, twenty times as
well as it does; if its surface were polished iron, it would only
radiate one-sixth as much as it does. Changes in the amount of the
conduction and radiation far less than these, would, probably,
subvert the whole _thermal_ constitution of the earth, and make it
uninhabitable by any of its present vegetable, or animal tenants.
One of the results of the laws of heat, as they exist in the globe,
is, that, by their action, the thermal state tends to a limiting
condition, which, once reached, remains constant and steady, as it
now is. The oscillations or excursions from the mean condition,
produced by any temporary cause, are rapidly suppressed; the
deviations of seasons from their usual standard produce only a
small and transient effect. The impression of an extremely hot
day upon the ground melts almost immediately into the average
internal heat. The effect of a hot summer, in like manner, is soon
lost in its progress through the globe. If this were otherwise,
if the inequalities and oscillations of heat went on, through the
interior of the earth, retaining the same value, or becoming larger
and larger, we might have the extreme heats or colds of one place
making their appearance at another place after a long interval;
like a conflagration which creeps along a street and bursts out at
a point remote from its origin.
It appears, therefore, that both the present differences of
climate, and the steadiness of the average at each place, depend
upon the form of the present laws of heat, and on the arbitrary
magnitudes which determine the rate of conduction and radiation.
The laws are such as to secure us from increasing and destructive
inequalities of heat; the arbitrary magnitudes are elements to
which the organic world is adjusted.
CHAPTER IX.
_The Laws of Heat with respect to Water._
The manner in which heat is transmitted through fluids is
altogether different from the mode in which it passes through
solids; and hence the waters of the earth’s surface produce
peculiar effects upon its condition as to temperature. Moreover,
water is susceptible of evaporation in a degree depending upon the
increase of heat; and in consequence of this property it has most
extensive and important functions to discharge in the economy of
nature. We will consider some of the offices of this fluid.
1. Heat is communicated through water, not by being _conducted_
from one part of the fluid to another, as in solid bodies, but
(at least principally) by being _carried_ with the parts of the
fluid by means of an intestine motion. Water expands and becomes
lighter by heat, and, therefore, if the upper parts be cooled
below the subjacent temperature, this upper portion will become
heavier than that below, bulk for bulk, and will descend through
it, while the lower portion rises to take the upper place. In this
manner the colder parts descend, and the warmer parts ascend by
contrary currents, and by their interchange and mixture, reduce
the whole to a temperature at least as low as that of the surface.
And this equalization of temperature by means of such currents,
is an operation of a much more rapid nature than the slow motion
of conduction by which heat creeps through a solid body. Hence,
alternations of heat and cold, as day and night, summer and
winter, produce in water, inequalities of temperature much smaller
than those which occur in a solid body. The heat communicated is
less, for transparent fluids imbibe heat very slowly; and the cold
impressed on the surface is soon diffused through the mass by
internal circulation.
Hence it follows that the ocean, which covers so large a portion
of the earth, and affects the temperature of the whole surface
by its influence, produces the effect of making the alternations
of heat and cold much less violent than they would be if it were
absent. The different temperatures of its upper and lower parts
produce a current which draws the seas, and by means of the seas,
the air, towards the mean temperature. And this kind of circulation
is produced, not only between the upper and lower parts, but also
between distant tracts of the ocean. The great Gulf Stream which
rushes out of the Gulf of Mexico, and runs across the Atlantic to
the western shores of Europe, carries with it a portion of the
tropical heat into northern regions: and the returning current
which descends along the coast of Africa, tends to cool the parts
nearer the equator. Great as the difference of temperature is in
different climates, it would be still greater if there were not
this equalizing and moderating power exerted constantly over the
whole surface. Without this influence, it is probable that the two
polar portions of the earth, which are locked in perpetual ice and
snow, and almost destitute of life, would be much increased.
We find an illustration of this effect of the ocean on temperature,
in the peculiarities of the climates of maritime tracts and
islands. The climate of such portions of the earth, corrected in
some measure by the temperature of the neighbouring sea, is more
equable than that of places in the same latitudes differently
situated. London is cooler in summer and warmer in winter than
Paris.
2. Water expands by heat and contracts by cold, as has been
already said; and in consequence of this property, the coldest
portions of the fluid generally occupy the lower parts. The
continued progress of cold produces congelation. If, therefore, the
law just mentioned had been strictly true, the lower parts of water
would have been first frozen; and being once frozen, hardly any
heat applied at the surface could have melted them, for the warm
fluid could not have descended through the colder parts. This is
so far the case, that in a vessel containing ice at the bottom and
water at the top, Rumford made the upper fluid boil without thawing
the congealed cake below.
Now, a law of water with respect to heat operating in this manner,
would have been very inconvenient if it had obtained in our lakes
and seas. They would all have had a bed of ice, increasing with
every occasion, till the whole was frozen. We could have had no
bodies of water, except such pools on the surfaces of these icy
reservoirs as the summer sun could thaw, to be again frozen to
the bottom with the first frosty night. The law of the regular
contraction of water by cold till it became ice, would, therefore,
be destructive of all the utility of our seas and lakes. How is
this inconvenience obviated?
It is obviated by a modification of the law which takes place when
the temperature approaches this limit. Water contracts by the
increase of cold, till we come _near_ the freezing temperature;
but then, by a further increase of cold, it contracts no more, but
expands till the point at which it becomes ice. It contracts in
cooling down to 40 degrees of Fahrenheit’s thermometer; in cooling
further it expands, and when cooled to 32 degrees, it freezes.
Hence, the greatest density of the fluid is at 40 degrees, and
water of this temperature, or near it, will lie at the bottom
with cooler water or with ice floating above it. However much the
surface be cooled, water colder than 40 cannot descend to displace
water warmer than itself. Hence we can never have ice formed at
the bottom of deep water. In approaching the freezing point, the
coldest water will rise to the surface, and the congelation will
take place there; and the ice so formed will remain at the surface,
exposed to the warmth of the sunbeams and the air, and will not
survive any long continuance of such action.
Another peculiarity in the laws which regulate the action of cold
on water is, that in the very act of freezing a further sudden
and considerable expansion takes place. Many persons will have
known instances of vessels burst by the freezing of water in them.
The consequence of this expansion is, that the specific gravity
of ice is less than that of water of any temperature; and it
therefore always floats in the unfrozen fluid. If this expansion of
crystallization did not exist, ice would float in water which was
below forty degrees, but would sink when the fluid was above that
temperature: as the case is, it floats under all circumstances. The
icy remnants of the effects of winter, which the river carries down
its stream, are visible on its surface till they melt away; and
the icebergs which are detached from the shores of the polar seas,
drift along, exposed to the sun and air, as well as to the water in
which they are immersed.
These laws of the effect of temperature on water are truly
remarkable in their adaptation to the beneficial course of things
at the earth’s surface. Water contracts by cold; it thus equalizes
the temperature of various times and places; but if its contraction
were continued all the way to the freezing point, it would bind a
great part of the earth in fetters of ice. The contraction then
is here replaced by expansion, in a manner which but slightly
modifies the former effects, while it completely obviates the bad
consequences. The further expansion which takes place at the point
of freezing, still further facilitates the rapid removal of the
icy chains, in which parts of the earth’s surface are at certain
seasons bound.
We do not know how far these laws of expansion are connected with
and depend on more remote and general properties of this fluid, or
of all fluids. But we have no reason to believe that, by whatever
means they operate, they are not laws selected from among other
laws which might exist, as in fact for other fluids other laws do
exist. And we have all the evidence, which the most remarkable
furtherance of important purposes can give us, that they _are_
selected, and selected with a beneficial design.
3. As water becomes ice by cold, it becomes steam by heat. In
common language, steam is the name given to the vapour of _hot_
water; but in fact a vapour or steam rises from water at all
temperatures, however low, and even from ice. The expansive force
of this vapour increases rapidly as the heat increases; so that
when we reach the heat of boiling water, it operates in a far
more striking manner than when it is colder; but in all cases
the surface of water is covered with an atmosphere of aqueous
vapour, the pressure or _tension_ of which is limited by the
temperature of the water. To each degree of pressure in steam there
is a _constituent temperature_ corresponding. If the surface of
water is not pressed by vapour with the force thus corresponding
to its temperature, an immediate _evaporation_ will supply the
deficiency. We can compare the tension of such vapour with that of
our common atmosphere; the pressure of the latter is measured by
the barometrical column, about thirty inches of mercury; that of
watery vapour is equal to one inch of mercury at the constituent
temperature of 80 degrees, and to one-fifth of an inch, at the
temperature of 32 degrees.
Hence, if that part of the atmosphere which consists of common air
were annihilated, there would still remain an atmosphere of aqueous
vapour, arising from the waters and moist parts of the earth; and
in the existing state of things this vapour rises in the atmosphere
of dry air. Its distribution and effects are materially influenced
by the vehicle in which it is thus carried, as we shall hereafter
notice; but at present we have to observe the exceeding _utility_
of water in this shape. We remark how suitable and indispensable to
the well-being of the creation it is, that the fluid should possess
the property of assuming such a form under such circumstances.
The _moisture_ which floats in the atmosphere is of most essential
use to vegetable life.[7] “The leaves of living plants appear to
act upon this vapour in its elastic form, and to absorb it. Some
vegetables increase in weight from this cause when suspended in the
atmosphere and unconnected with the soil, as the house-leek and the
aloe. In very intense heats, and when the soil is dry, the life
of plants seems to be preserved by the absorbent power of their
leaves.” It follows from what has already been said, that, with an
increasing heat of the atmosphere, an increasing quantity of vapour
will rise into it, if supplied from any quarter. Hence it appears
that aqueous vapour is most abundant in the atmosphere when it is
most needed for the purposes of life; and that when other sources
of moisture are cut off, this is most copious.
4. _Clouds_ are produced by aqueous vapour when it returns to the
state of water. This process is _condensation_, the reverse of
evaporation. When vapour exists in the atmosphere, if in any manner
the temperature becomes lower than the _constituent temperature_,
requisite for the maintenance of the vapoury state, some of the
steam will be condensed and will become water. It is in this manner
that the curl of steam from the spout of a boiling tea-kettle
becomes visible, being cooled down as it rushes to the air. The
steam condenses into a fine watery powder, which is carried about
by the little aerial currents. Clouds are of the same nature with
such curls, the condensation being generally produced when air,
charged with aqueous vapour, is mixed with a colder current, or has
its temperature diminished in any other manner.
Clouds, while they retain that shape, are of the most essential
use to vegetable and animal life. They moderate the fervour of
the sun, in a manner agreeable, to a greater or less degree, in
all climates, and grateful no less to vegetables than to animals.
Duhamel says that plants grow more during a week of cloudy weather
than a month of dry and hot. It has been observed that vegetables
are far more refreshed by being watered in cloudy than in clear
weather. In the latter case, probably the supply of fluid is too
rapidly carried off by evaporation. Clouds also moderate the
alternations of temperature, by checking the radiation from the
earth. The coldest nights are those which occur under a cloudless
winter sky.
The uses of clouds, therefore, in this stage of their history,
are by no means inconsiderable, and seem to indicate to us that
the laws of their formation were constructed with a view to the
purposes of organized life.
5. Clouds produce _rain_. In the formation of a cloud the
precipitation of moisture probably forms a fine watery _powder_,
which remains suspended in the air in consequence of the minuteness
of its particles: but if from any cause the precipitation is
collected in larger portions, and becomes _drops_, these descend by
their weight and produce a shower.
However rain is formed, it is one of the consequences of the
capacity of evaporation and condensation which belongs to water,
and its uses are the result of the laws of those processes. Its
uses to plants are too obvious and too numerous to be described. It
is evident that on its quantity and distribution depend in a great
measure the prosperity of the vegetable kingdom: and different
climates are fitted for different productions, no less by the
relations of dry weather and showers, than by those of hot and cold.
6. Returning back still further in the changes which cold can
produce on water, we come to _snow_ and _ice_: snow being
apparently frozen vapour, aggregated by a confused action of
crystalline laws; and ice being water in its fluid state,
solidified by the same crystalline forces. The impression of
these agents on the animal feelings is generally unpleasant,
and we are in the habit of considering them as symptoms of the
power of winter to interrupt that state of the elements in which
they are subservient to life. Yet, even in this form, they are
not without their uses.[8] “Snow and ice are bad conductors of
cold; and when the ground is covered with snow, or the surface
of the soil or of water is frozen, the roots or bulbs of plants
beneath are protected by the congealed water from the influence
of the atmosphere, the temperature of which, in northern winters,
is usually very much below the freezing point; and this water
becomes the first nourishment of the plant in early spring. The
expansion of water during its congelation, at which time its volume
increases one-twelfth, and its contraction in bulk during a thaw,
tend to pulverize the soil, to separate its parts from each other,
and to make it more permeable to the influence of the air.” In
consequence of the same slowness in the conduction of heat which
snow thus possesses, the arctic traveller finds his bed of snow
of no intolerable coldness; the Esquimaux is sheltered from the
inclemency of the season in his snow hut, and travels rapidly and
agreeably over the frozen surface of the sea. The uses of those
arrangements, which at first appear productive only of pain and
inconvenience, are well suited to give confidence and hope to our
researches for such usefulness in every part of the creation. They
have thus a peculiar value in adding connexion and universality to
our perception of beneficial design.
7. There is a peculiar circumstance still to be noticed in the
changes from ice to water and from water to steam. These changes
take place at a particular and invariable degree of heat; yet
they do not take place suddenly when we increase the heat to this
degree. This is a very curious arrangement. The temperature _makes
a stand_, as it were, at the point where thaw, and where boiling
take place. It is necessary to apply a considerable quantity of
heat to produce these effects; all which heat disappears, or
becomes _latent_, as it is called. We cannot raise the temperature
of a thawing mass of ice till we have thawed the whole. We cannot
raise the temperature of boiling water, or of steam rising from it,
till we have converted all the water into steam. Any heat that we
apply while these changes are going on is absorbed in producing the
changes.
The consequences of this property of _latent heat_ are very
important. It is on this account that the changes now spoken of
necessarily occupy a considerable time. Each part in succession
must have a proper degree of heat applied to it. If it were
otherwise, thaw and evaporation must be instantaneous: at the
first touch of warmth, all the snow which lies on the roofs of our
houses would descend like a waterspout into the streets: all that
which rests on the ground would rush like an inundation into the
water courses. The hut of the Esquimaux would vanish like a house
in a pantomime: the icy floor of the river would be gone without
giving any warning to the skaiter or the traveller: and when, in
heating our water, we reached the boiling point, the whole fluid
would “flash into steam,” (to use the expression of engineers,)
and dissipate itself in the atmosphere, or settle in dew on the
neighbouring objects.
It is obviously necessary for the purposes of human life, that
these changes should be of a more gradual and manageable kind
than such as we have now described. Yet this gradual progress of
freezing and thawing, of evaporation and condensation, is produced,
so far as we can discover, by a particular contrivance. Like the
freezing of water from the top, or the floating of ice, the
moderation of the rate of these changes seems to be the result of
a _violation_ of a law: that is, the simple rule regarding the
effects of change of temperature, which at first sight appears to
be the law, and which, from its simplicity, would seem to us the
most obvious laws for these as well as other cases, is modified
at certain critical points, _so as to_ produce these advantageous
effects:--why may we not say _in order to_ produce such effects?
8. Another office of water which it discharges by means of its
relations to heat, is that of supplying our _springs_. There can be
no doubt that the old hypotheses which represent springs as drawing
their supplies from large subterranean reservoirs of water, or from
the sea by a process of subterraneous filtration, are erroneous
and untenable. The quantity of evaporation from water and from wet
ground is found to be amply sufficient to supply the requisite
drain. Mr. Dalton calculated[9] that the quantity of rain which
falls in England is thirty-six inches a year. Of this he reckoned
that thirteen inches flow off to the sea by the rivers, and that
the remaining twenty-three inches are raised again from the ground
by evaporation. The thirteen inches of water are of course supplied
by evaporation from the sea, and are carried back to the land
through the atmosphere. Vapour is perpetually rising from the
ocean, and is condensed in the hills and high lands, and through
their pores and crevices descends, till it is deflected, collected,
and conducted out to the bay, by some stratum or channel which is
watertight. The condensation which takes place in the higher parts
of the country, may easily be recognised in the mists and rains
which are the frequent occupants of such regions. The coldness of
the atmosphere and other causes precipitate the moisture in clouds
and showers, and in the former as well as in the latter shape, it
is condensed and absorbed by the cool ground. Thus a perpetual and
compound circulation of the waters is kept up; a narrower circle
between the evaporation and precipitation of the land itself,
the rivers and streams only occasionally and partially forming a
portion of the circuit; and a wider interchange between the sea and
the lands which feed the springs, the water ascending perpetually
by a thousand currents through the air, and descending by the
gradually converging branches of the rivers, till it is again
returned into the great reservoir of the ocean.
In every country, these two portions of the aqueous circulation
have their regular, and nearly constant, proportion. In this
kingdom the relative quantities are, as we have said, twenty-three
and thirteen. A due distribution of these circulating fluids in
each country appears to be necessary to its organic health; to the
habits of vegetables, and of man. We have every reason to believe
that it is kept up from year to year as steadily as the circulation
of the blood in the veins and arteries of man. It is maintained by
a machinery very different, indeed, from that of the human system,
but apparently as well, and, therefore, we may say as clearly, as
that, adapted to its purposes.
By this machinery, we have a connexion established between the
atmospheric changes of remote countries. Rains in England are often
introduced by a south-east wind. “Vapour brought to us by such
a wind, must have been generated in countries to the south and
east of our island. It is, therefore, probably, in the extensive
valleys watered by the Meuse, the Moselle, and the Rhine, if not
from the more distant Elbe, with the Oder and the Weser, that the
water rises, in the midst of sunshine, which is soon afterwards
to form _our_ clouds, and pour down _our_ thunder-showers.”
“Drought and sunshine in one part of Europe may be as necessary
to the production of a wet season in another, as it is on the
great scale of the continents of Africa and South America; where
the plains, during one-half the year, are burnt up, to feed
the springs of the mountain; which in their turn contribute to
inundate the fertile valleys and prepare them for a luxuriant
vegetation.”[10] The properties of water which regard heat make one
vast _watering-engine_ of the atmosphere.
CHAPTER X.
_The Laws of Heat with respect to Air._
We have seen in the preceding chapter how many and how important
are the offices discharged by the aqueous part of the atmosphere.
The aqueous part is, however, a very small part only; it may
vary, perhaps, from less than 1-100th to nearly as much as 1-20th
in weight, of the whole aerial ocean. We have to offer some
considerations with regard to the remainder of the mass.
1. In the first place we may observe that the aerial atmosphere is
necessary as a vehicle for the aqueous vapour. Salutary as is the
operation of this last element to the whole organized creation, it
is a substance which would not have answered its purposes if it had
been administered pure. It requires to be diluted and associated
with dry air, to make it serviceable. A little consideration will
show this.
We can suppose the earth with no atmosphere except the vapour
which arises from its watery parts: and if we suppose also the
equatorial parts of the globe to be hot, and the polar parts cold,
we may easily see what would be the consequence. The waters at
the equator, and near the equator, would produce steam of greater
elasticity, rarity, and temperature, than that which occupies the
regions further _polewards_; and such steam, as it came in contact
with the colder vapour of a higher latitude, would be precipitated
into the form of water. Hence there would be a perpetual current
of steam from the equatorial parts towards each pole, which would
be condensed, would fall to the surface, and flow back to the
equator in the form of fluid. We should have a circulation which
might be regarded as a species of regulated distillation.[11] On
a globe so constituted, the sky of the equatorial zone would be
perpetually cloudless; but in all other latitudes we should have an
uninterrupted shroud of clouds, fogs, rains, and, near the poles, a
continual fall of snow. This would be balanced by a constant flow
of the currents of the ocean from each pole towards the equator. We
should have an excessive circulation of moisture, but no sunshine,
and probably only minute changes in the intensity and appearances
of one eternal drizzle or shower.
It is plain that this state of things would but ill answer the ends
of vegetable and animal life: so that even if the lungs of animals
and the leaves of plants were so constructed as to breathe steam
instead of air, an atmosphere of unmixed steam would deprive those
creatures of most of the other external conditions of their well
being.
The real state of things which we enjoy, the steam being mixed
in our breath and in our sky in a moderate quantity, gives rise
to results very different from those which have been described.
The machinery by which these results are produced is not a little
curious. It is in fact the machinery of the _weather_, and
therefore the reader will not be surprised to find it both complex
and apparently uncertain in its working. At the same time some
of the general principles which govern it seem now to be pretty
well made out, and they offer no small evidence of beneficent
arrangement.
Besides our atmosphere of aqueous vapour, we have another and far
larger atmosphere of common air; a _permanently elastic_ fluid,
that is, one which is not condensed into a liquid form by pressure
or cold, such as it is exposed to in the order of natural events.
The pressure of the dry air is about twenty-nine and a half inches
of mercury; that of the watery vapour, perhaps, half an inch. Now
if we had the earth quite dry, and covered with an atmosphere of
dry air, we can trace in a great measure what would be the results,
supposing still the equatorial zone to be hot, and the temperature
of the surface to decrease perpetually as we advance into higher
latitudes. The air at the equator would be rarefied by the heat,
and would be perpetually displaced below by the denser portions
which belonged to cooler latitudes. We should have a current of
air from the equator to the poles in the higher regions of the
atmosphere, and at the surface a returning current setting towards
the equator to fill up the void so created. Such aerial currents,
combined with the rotatory motion of the earth, would produce
oblique winds; and we have in fact instances of winds so produced,
in the trade winds, which between the tropics blow constantly from
the quarters between east and north, and are, we know, balanced
by opposite currents in higher regions. The effect of a heated
surface of land would be the same as that of the heated zone of the
equator, and would attract to it a sea breeze during the day time,
a phenomenon, as we also know, of perpetual occurrence.
Now a mass of dry air of such a character as this, is by far the
dominant part of our atmosphere; and hence carries with it in its
motions the thinner and smaller eddies of aqueous vapour. The
latter fluid may be considered as permeating and moving in the
interstices of the former, as a spring of water flows through a
sand rock.[12] The lower current of air is, as has been said,
directed towards the equator, and hence it resists the motion of
the steam, the tendency of which is in the opposite direction; and
prevents or much retards that continual flow of hot vapour into
colder regions, by which a constant precipitation would take place
in the latter situations.
If, in this state of things, the flow of the current of air, which
blows from any colder place into a warmer region, be retarded or
stopped, the aqueous vapours will now be able to make their way
to the colder point, where they will be precipitated in clouds or
showers.
Thus, in the lower part of the atmosphere, there are tendencies
to a current of air in one direction, and a current of vapour in
the opposite; and these tendencies exist in the average weather
of places situated at a moderate distance from the equator. The
air tends from the colder to the warmer parts, the vapour from the
warmer to the colder.
The various distribution of land and sea, and many other causes
make these currents far from simple. But in general the air current
predominates, and keeps the skies clear and the moisture dissolved.
Occasional and irregular occurrences disturb this predominance;
the moisture is then precipitated, the skies are clouded, and the
clouds may descend in copious rains.
These alternations of fair weather and showers, appear to be much
more favourable to vegetable and animal life than any uniform
course of weather could have been. To produce this variety, we have
two antagonist forces, by the struggle of which such changes occur.
Steam and air, two transparent and elastic fluids, expansible by
heat, are in many respects and properties very like each other.
Yet, the same heat similarly applied to the globe, produces at the
surface currents of these fluids, tending in opposite directions.
And these currents mix and balance, conspire and interfere, so
that our trees and fields have alternately water and sunshine;
our fruits and grain are successively developed and matured. Why
should such laws of heat and elastic fluids so obtain, and be so
combined? Is it not in order that they may be fit for such offices?
There is here an arrangement, which no chance could have produced.
The details of this apparatus may be beyond our power of tracing;
its springs may be out of our sight. Such circumstances do not make
it the less a curious and beautiful contrivance: they need not
prevent our recognizing the skill and benevolence which we _can_
discover.
2. But we have not yet done with the machinery of the weather. In
ascending from the earth’s surface through the atmosphere, we find
a remarkable difference in the heat and in the pressure of the air.
It becomes much colder, and much lighter; men’s feelings tell them
this; and the thermometer and barometer confirm these indications.
And here again we find something to remark.
In both the simple atmospheres of which we have spoken, the one of
air and the one of steam, the property which we have mentioned must
exist. In each of them, both the temperature and the tension would
diminish in ascending. But they would diminish at very different
rates. The temperature, for instance, would decrease much more
rapidly for the same height in dry air than in steam. If we begin
with a temperature of 80 degrees at the surface, on ascending five
thousand feet the steam is still 76½ degrees, the air is only 64½
degrees; at ten thousand feet, the steam is 73 degrees, the air
48½ degrees; at fifteen thousand feet, steam is at 70 degrees,
air has fallen below the freezing point to 31½ degrees. Hence
these two atmospheres cannot exist together without modifying one
another: one must heat or cool the other, so that the coincident
parts may be of the same temperature. This accordingly does take
place, and this effect influences very greatly the constitution
of the atmosphere. For the most part, the steam is compelled to
accommodate itself to the temperature of the air, the latter being
of much the greater bulk. But if the upper parts of the aqueous
vapour be cooled down to the temperature of the air, they will not
by any means exert on the lower parts of the same vapour so great a
pressure as the gaseous form of these could bear. Hence, there will
be a deficiency of moisture in the lower part of the atmosphere,
and if water exist there, it will rise by evaporation, the surface
feeling an insufficient tension; and there will thus be a fresh
supply of vapour upwards. As, however, the upper regions already
contain as much as their temperature will support in the state of
gas, a precipitation will now take place, and the fluid thus formed
will descend till it arrives in a lower region, where the tension
and temperature are again adapted to its evaporation.
Thus, we can have no equilibrium in such an atmosphere, but a
perpetual circulation of vapour between its upper and lower parts.
The currents of air which move about in different directions, at
different altitudes, will be differently charged with moisture, and
as they touch and mingle, lines of cloud are formed, which grow and
join, and are spread out in floors, or rolled together in piles.
These, again, by an additional accession of humidity, are formed
into drops, and descend in showers into the lower regions, and if
not evaporated in their fall, reach the surface of the earth.
The varying occurrences thus produced, tend to multiply and extend
their own variety. The ascending streams of vapour carry with them
that _latent heat_ belonging to their gaseous state, which, when
they are condensed, they give out as sensible heat. They thus
raise the temperature of the upper regions of air, and occasion
changes in the pressure and motion of its currents. The clouds,
again, by shading the surface of the earth from the sun, diminish
the evaporation by which their own substance is supplied, and
the heating effects by which currents are caused. Even the mere
mechanical effects of the currents of fluid on the distribution of
its own pressure, and the dynamical conditions of its motion, are
in a high degree abstruse in their principles and complex in their
results. It need not be wondered, therefore, if the study of this
subject is very difficult and entangled, and our knowledge, after
all, very imperfect.
In the middle of all this apparent confusion, however, we can
see much that we can understand. And, among other things, we may
notice some of the consequences of the difference of the laws
of temperature followed by steam and by air in going upwards.
One important result is that the atmosphere is much drier, near
the surface, than it would have been if the laws of density and
temperature had been the same for both gases. If this had been so,
the air would always have been _saturated_ with vapour. It would
have contained as much as the existing temperature could support,
and the slightest cooling of any object would have covered it with
a watery film like dew. As it is, the air contains much less than
its full quantity of vapour: we may often cool an object ten,
twenty, or thirty degrees without obtaining a deposition of water
upon it, or reaching the _dew-point_, as it is called. To have had
such a _dripping_ state of the atmosphere as the former arrangement
would have produced, would have been inconvenient, and so far
as we can judge, unsuited to vegetables as well as animals. No
evaporation from the surface of either could have taken place under
such conditions.
The sizes and forms of clouds appear to depend on the same
circumstance, of the air not being saturated with moisture. And it
is seemingly much better that clouds should be comparatively small
and well defined, as they are, than that they should fill vast
depths of the atmosphere with a thin mist, which would have been
the consequence of the imaginary condition of things just mentioned.
Here then we have another remarkable exhibition of two laws, in
two nearly similar gaseous fluids, producing effects alike in kind,
but different in degree, and by the _play_ of their difference
giving rise to a new set of results, peculiar in their nature and
beneficial in their tendency. The _form_ of the laws of air and
of steam with regard to heat might, so far as we can see, have
been more similar, or more dissimilar, than it now is: the rate of
each law might have had a different amount from its present one,
so as quite to alter the relation of the two. By the laws having
such forms and such rates as they have, effects are produced, some
of which we can distinctly perceive to be beneficial. Perhaps
most persons will feel a strong persuasion, that if we understood
the operation of these laws more distinctly, we should see still
more clearly the beneficial tendency of these effects, and should
probably discover others, at present concealed in the apparent
perplexity of the subject.
3. From what has been said, we may see, in a general way, both the
causes and the effects of _winds_. They arise from any disturbance
by temperature, motion, pressure, &c. of the equilibrium of the
atmosphere, and are the efforts of nature to restore the balance.
Their office in the economy of nature is to carry heat and moisture
from one tract to another, and they are the great agents in the
distribution of temperature and the changes of weather. Other
purposes might easily be ascribed to them in the business of the
vegetable and animal kingdoms, and in the arts of human life, of
which we shall not here treat. That character in which we now
consider them, that of the machinery of atmospheric changes, and
thus, immediately or remotely, the instruments of atmospheric
influences, cannot well be refused them by any person.
4. There is still one reflexion which ought not to be omitted.
All the changes of the weather, even the most violent tempests
and torrents of rain, may be considered as oscillations about the
mean or average condition belonging to each place. All these
oscillations are limited and transient; the storm spends its fury,
the inundation passes off, the sky clears, the calmer course of
nature succeeds. In the forces which produce this derangement,
there is a provision for making it short and moderate. The
oscillation stops of itself, like the rolling of a ship, when
no longer impelled by the wind. Now, why should this be so? Why
should the oscillations, produced by the conflict of so many laws,
seemingly quite unconnected with each other, be of this converging
and subsiding character? Would it be so under all arrangements? Is
it a matter of mechanical necessity that disturbance must end in
the restoration of the medium condition? By no means. There may
be an utter subversion of the equilibrium. The ship may roll too
far, and may _capsize_. The oscillations may go on, becoming larger
and larger, till all trace of the original condition is lost; till
new forces of inequality and disturbance are brought into play;
and disorder and irregularity may succeed, without apparent limit
or check in its own nature, like the spread of a conflagration in
a city. This is a possibility in any combination of mechanical
forces; why does it not happen in the one now before us? By what
good fortune are the powers of heat, of water, of steam, of air,
the effects of the earth’s annual and diurnal motions, and probably
other causes, so adjusted, that through all their struggles the
elemental world goes on, upon the whole, so quietly and steadily?
Why is the whole fabric of the weather never utterly deranged, its
balance lost irrecoverably? Why is there not an eternal conflict,
such as the poets imagine to take place in their chaos?
“For Hot, Cold, Moist, and Dry, four champions fierce,
Strive here for mastery, and to battle bring
Their embryon atoms:--
to whom these most adhere,
He rules _a moment_: Chaos umpire sits,
And by decision more embroils the fray.”--_Par. Lost._ b. ii.
A state of things something like that which Milton here seems to
have imagined, is, so far as we know, not mechanically impossible.
It might have continued to obtain, if Hot and Cold, and Moist and
Dry had not been compelled to “run into their places.” It will be
hereafter seen, that in the comparatively simple problem of the
solar system, a number of very peculiar adjustments were requisite,
in order that the system might retain a permanent form, in order
that its motions might have their cycles, its perturbations their
limits and period. The problem of the continuation of such laws and
materials as enter into the constitution of the atmosphere, is one
manifestly of much greater complexity, and indeed to us probably
of insurmountable difficulty as a mechanical problem. But all that
investigation and analogy teach us, tends to show that it will
resemble the other problem in the nature of its result; and that
certain relations of its data, and of the laws of its elements,
are necessary requisites, for securing the stability of its mean
condition, and for giving a small and periodical character to its
deviations from such a condition.
It would then be probable, from this reflection alone, that in
determining the quantity and the law and intensity of the forces,
of earth, water, air, and heat, the same regard has been shown to
the permanency and stability of the terrestrial system, which may
be traced in the adjustment of the masses, distances, positions,
and motions of the bodies of the celestial machine.
This permanency appears to be, of itself, a suitable object of
contrivance. The purpose for which the world was made could be
answered only by its being preserved. But it has appeared, from
the preceding part of this and the former chapter, that this
permanence is a permanence of a state of things adapted by the most
remarkable and multiplied combinations to the well-being of man, of
animals, of vegetables. The adjustments and conditions therefore,
beyond the reach of our investigation as they are, by which its
permanence is secured, must be conceived as fitted to add, in each
of the instances above adduced, to the admiration which the several
manifestations of Intelligent Beneficence are calculated to excite.
CHAPTER XI.
_The Laws of Electricity._
Electricity undoubtedly exists in the atmosphere in most states of
the air; but we know very imperfectly the laws of this agent, and
are still more ignorant of its atmospheric operation. The present
state of science does not therefore enable us to perceive those
adaptations of its laws to its uses, which we can discover in those
cases where the laws and the uses are both of them more apparent.
We can, however, easily make out that electrical agency plays a
very considerable part among the clouds, in their usual conditions
and changes. This may be easily shown by Franklin’s experiment of
the electrical kite. The clouds are sometimes positively, sometimes
negatively, charged, and the rain which descends from them offers
also indications of one or other kind of electricity. The changes
of wind and alterations of the form of the clouds are generally
accompanied with changes in these electrical indications. Every one
knows that a thunder-cloud is strongly charged with the electric
fluid, (if it be a fluid,) and that the stroke of the lightning
is an electrical discharge. We may add that it appears, by recent
experiments, that a transfer of electricity between plants and
the atmosphere is perpetually going on during the process of
vegetation.
We cannot trace very exactly the precise circumstances, in the
occurrences of the atmospheric regions, which depend on the
influence of the laws of electricity: but we are tolerably certain,
from what has been already noticed, that if these laws did not
exist, or were very different from what they now are, the action of
the clouds and winds, and the course of vegetation, would also be
other than it now is.
It is therefore at any rate very probable that electricity has its
appointed and important purposes in the economy of the atmosphere.
And this being so, we may see a use in the thunder-storm and the
stroke of the lightning. These violent events are, with regard to
the electricity of the atmosphere, what winds are with regard to
heat and moisture. They restore the equilibrium where it has been
dissolved, and carry the fluid from places where it is superfluous,
to others where it is deficient.
We are so constituted, however, that these crises impress almost
every one with a feeling of awe. The deep lowering gloom of the
thunder-cloud, the overwhelming burst of the explosion, the flash
from which the steadiest eye shrinks, and the irresistible arrow of
the lightning which no earthly substance can withstand, speak of
something fearful, even independently of the personal danger which
they may whisper. They convey, far more than any other appearance
does, the idea of a superior and mighty power, manifesting
displeasure and threatening punishment. Yet we find that this is
not the language which they speak to the physical inquirer: he sees
these formidable symptoms only as the means or the consequences
of good. What office the thunderbolt and the whirlwind may have
in the _moral_ world, we cannot here discuss: but certainly _he_
must speculate as far beyond the limits of philosophy as of piety,
who pretends to have learnt that there their work has more of evil
than of good. In the _natural_ world, these apparently destructive
agents are, like all the other movements and appearances of the
atmosphere, parts of a great scheme, of which every discoverable
purpose is marked with beneficence as well as wisdom.
CHAPTER XII.
_The Laws of Magnetism._
Magnetism has no very obvious or apparently extensive office in
the mechanism of the atmosphere and the earth: but the mention of
it may be introduced, because its ascertained relations to the
other powers which exist in the system are well suited to show us
the connexion subsisting throughout the universe, and to check the
suspicion, if any such should arise, that any law of nature is
without its use. The parts of creation when these uses are most
obscure, are precisely those parts when the laws themselves are
least known.
When indeed we consider the vast service of which magnetism is to
man, by supplying him with that invaluable instrument the mariners’
compass, many persons will require no further evidence of this
property being introduced into the frame of things with a worthy
purpose. As however, we have hitherto excluded _use in the arts_
from our line of argument, we shall not here make an exception in
favour of navigation, and what we shall observe belongs to another
view of the subject.
Magnetism has been discovered in modern times to have so close
a connexion with galvanism, that they may be said to be almost
different aspects of the same agent. All the phenomena which we can
produce with magnets, we can imitate with coils of galvanic wire.
That galvanism exists in the earth, we need no proof. Electricity,
which appears to be only galvanism in equilibrium, is there in
abundance; and recently, Mr. Fox[13] has shown by experiment that
metalliferous veins, as they lie in the earth, exercise a galvanic
influence on each other. Something of this kind might have been
anticipated; for masses of metal in contact, if they differ in
temperature or other circumstances, are known to produce a galvanic
current. Hence we have undoubtedly streams of galvanic influence
moving along in the earth. Whether or not such causes as these
produce the directive power of the magnetic needle, we cannot here
pretend to decide; they can hardly fail to affect it. The Aurora
Borealis too, probably an electrical phenomenon, is said, under
particular circumstances, to agitate the magnetic needle. It is
not surprising, therefore, that, if electricity have an important
office in the atmosphere, magnetism should exist in the earth. It
seems likely, that the magnetic properties of the earth may be
collateral results of the existence of the same cause by which
electrical agency operates; an agency which, as we have already
seen, has important offices in the processes of vegetable life. And
thus magnetism belongs to the same system of beneficial contrivance
to which electricity has been already traced.
We see, however, on this subject very dimly and a very small way.
It can hardly be doubted that magnetism has other functions than
those we have noticed.
CHAPTER XIII.
_The Properties of Light with regard to Vegetation._
The illuminating power of light will come under our consideration
hereafter. Its agency, with regard to organic life, is too
important not to be noticed, though this must be done briefly.
Light appears to be as necessary to the health of plants as air
of moisture. A plant may, indeed, grow without it, but it does
not appear that a species could be so continued. Under such a
privation, the parts which are usually green, assume a white
colour, as is the case with vegetables grown in a cellar, or
protected by a covering for the sake of producing this very effect;
thus, celery, is in this manner blanched, or _etiolated_.
The part of the process of vegetable life for which light is
especially essential, appears to be the functions of the leaves;
these are affected by this agent in a very remarkable manner.
The moisture which plants imbibe is, by their vital energies,
carried to their leaves; and is then brought in contact with the
atmosphere, which, besides other ingredients, contains, in general,
a portion of carbonic acid. _So long as light is present_, the
leaf decomposes the carbonic acid, appropriates the carbon to the
formation of its own proper juices, and returns the disengaged
oxygen into the atmosphere; thus restoring the atmospheric air to
a condition in which it is more fitted than it was before for the
support of animal life. The plant thus prepares the support of
life for other creatures at the same time that it absorbs its own.
The greenness of those members which affect that colour, and the
disengagement of oxygen, are the indications that its vital powers
are in healthful action: as soon as we remove light from the plant,
these indications cease: it has no longer power to imbibe carbon
and disengage oxygen, but on the contrary, it gives back some of
the carbon already obtained, and robs the atmosphere of oxygen for
the purpose of reconverting this into carbonic acid.
It cannot well be conceived that such effects of light on
vegetables, as we have described, should occur, if that agent, of
whatever nature it is, and those organs, had not been adapted to
each other. But the subject is here introduced that the reader may
the more readily receive the conviction of combining purpose which
must arise, on finding that an agent possessing these very peculiar
chemical properties, is employed to produce also those effects of
illumination, vision, &c., which form the most obvious portion of
the properties of light.
CHAPTER XIV.
_Sound._
Besides the function which air discharges as the great agent in the
changes of meteorology and vegetation, it has another office, also
of great and extensive importance, as the vehicle of sound.
1. The communication of sound through the air takes place by means
of a process altogether different from anything of which we have
yet spoken: namely, by the propagation of minute _vibrations_ of
the particles from one part of the fluid mass to another, without
any local motion of the fluid itself.
Perhaps we may most distinctly conceive the kind of effect here
spoken of, by comparing it to the motion produced by the wind in a
field of standing corn; grassy waves travel visibly over the field,
in the direction in which the wind blows, but this appearance of
an object moving is delusive. The only real motion is that of the
ears of grain, of which each goes and returns, as the stalk stoops
and recovers itself. This motion affects _successively_ a line of
ears in the direction of the wind, and affects _simultaneously_ all
those ears of which the elevation or depression forms one visible
wave. The elevations and depressions are propagated in a constant
direction, while the parts with which the space is filled only
vibrate to and fro. Of exactly such a nature is the propagation
of sound through the air. The particles of air go and return
through very minute spaces, and this vibratory motion runs through
the atmosphere from the sounding body to the ear. Waves, not of
elevation and depression, but of condensation and rarefaction, are
transmitted; and the sound thus becomes an object of sense to the
organ.
Another familiar instance of the propagation of vibrations we have
in the circles on the surface of smooth water, which diverge from
the point where it is touched by a small object, as a drop of
rain. In the beginning of a shower, for instance, when the drops
come distinct, though frequent, we may see each drop giving rise
to a ring, formed of two or three close concentric circles, which
grow and spread, leaving the interior of the circles smooth, and
gradually reaching parts of the surface more and more distant from
their origin. In this instance, it is clearly not a portion of the
water which flows onwards; but the disturbance, the rise and fall
of the surface which makes the ring-formed waves, passes into wider
and wider circles, and thus the undulation is transmitted from its
starting-place, to points in all directions on the surface of the
fluid.
The diffusion of these ring-formed undulations from their centre
resembles the diffusion of a sound from the place where it is
produced to the points where it is heard. The disturbance, or
vibration, by which it is conveyed, travels at the same rate in
all directions, and the waves which are propagated are hence of a
circular form. They differ, however, from those on the surface of
water; for sound is communicated upwards and downwards, and in all
intermediate directions, as well as horizontally; hence the waves
of sound are spherical, the point where the sound is produced being
the centre of the sphere.
This diffusion of vibrations in spherical shells of successive
condensation and rarefaction, will easily be seen to be different
from any local motion of the air, as wind, and to be independent of
that. The circles on the surface of water will spread on a river
which is flowing, provided it be smooth, as well as on a standing
canal.
Not only are such undulations propagated almost undisturbed by
any local motion of the fluid in which they take place, but also,
many may be propagated in the same fluid at the same time, without
disturbing each other. We may see this effect on water. When
several drops fall near each other, the circles which they produce
cross each other, without either of them being lost, and the
separate courses of the rings may still be traced.
All these consequences, both in water, in air, and in any other
fluid, can be very exactly investigated upon mechanical principles,
and the greater part of the phenomena can thus be shown to result
from the properties of the fluids.
There are several remarkable circumstances in the way in which air
answers its purpose as the vehicle of sound, of which we will now
point out a few.
2. The _loudness_ of sound is such as is convenient for common
purposes. The organs of speech can, in the present constitution of
the air, produce, without fatigue, such a tone of voice as can be
heard with distinctness and with comfort. That any great alteration
in this element might be incommodious, we may judge from the
difficulties to which persons are subject who are dull of hearing,
and from the disagreeable effects of a voice much louder than
usual, or so low as to be indistinct. Sounds produced by the human
organs, with other kinds of air, are very different from those in
our common air. If a man inhale a quantity of hydrogen gas, and
then speak, his voice is scarcely audible.
The loudness of sounds become smaller in proportion as they come
from a greater distance. This enables us to judge of the distance
of objects, in some degree at least, by the sounds which proceed
from them. Moreover, it is found that we can judge of the position
of objects by the ear: and this judgment seems to be formed by
comparing the loudness of the impression of the same sound on the
two ears and two sides of the head.[14]
The loudness of sounds appears to depend on the _extent_ of
vibration of the particles of air, and this is determined by the
vibrations of the sounding body.
3. The _pitch_, or the _differences of acute and grave_, in sounds,
form another important property, and one which fits them for a
great part of their purposes. By the succession of different
_notes_, we have all the results of melody and harmony in musical
sound; and of intonation and modulation of the voice, of accent,
cadence, emphasis, expression, passion, in speech. The song of
birds, which is one of their principal modes of communication,
depends chiefly for its distinctions and its significance upon the
combinations of acute and grave.
These differences are produced by the different _rapidity_ of
vibration of the particles of air. The gravest sound has about
eighty vibrations in a second, the most acute about one thousand.
Between these limits each sound has a musical character, and from
the different relations of the number of vibrations in a second
arise all the differences of musical intervals, concords and
discords.
4. The _quality_ of sounds is another of their differences. This is
the name given to the difference of notes of the same pitch, that
is the same note as to acute and grave, when produced by different
instruments. If a flute and a violin be in unison, the notes are
still quite different sounds. It is this kind of difference which
distinguishes the voice of one man from that of another: and it is
manifestly therefore one of great consequence; since it connects
the voice with the particular person, and is almost necessary in
order that language may be a medium of intercourse between men.
5. The _articulate_ character of sounds is for us one of the most
important arrangements which exist in the world; for it is by this
that they become the interpreters of thought, will and feeling, the
means by which a person can convey his wants, his instructions,
his promises, his kindness, to others; by which one man can
regulate the actions and influence the convictions and judgments
of another. It is in virtue of the possibility of shaping air into
words, that the imperceptible vibrations which a man produces in
the atmosphere, become some of his most important actions; the
foundations of the highest moral and social relations; and the
condition and instrument of all the advancement and improvement of
which he is susceptible.
It appears that the differences of articulate sound arise from
the different form of the cavity through which the sound is made
to proceed immediately _after_ being produced. In the human voice
the sound is produced in the larynx, and modified by the cavity of
the mouth, and the various organs which surround this cavity. The
laws by which articulate sounds are thus produced have not yet been
fully developed, but appear to be in the progress of being so.
The properties of sounds which have been mentioned, differences
of loudness, of pitch, of quality, and articulation, appear to be
all requisite in order that sound shall answer its purposes in
the economy of animal and of human life. And how was the air made
capable of conveying these four differences, at the same time that
the organs were made capable of producing them? Surely by a most
refined and skilful adaptation, applied with a most comprehensive
design.
6. Again; is it by chance that the air and the _ear_ exist
together? Did the air produce the organization of the ear? or the
ear, independently organized, anticipate the constitution of the
atmosphere? Or is not the only intelligible account of the matter,
this, that one was made for the other: that there is a mutual
adaptation produced by an Intelligence which was acquainted with
the properties of both; which adjusted them to each other as we
find them adjusted, in order that birds might communicate by song,
that men might speak and hear, and that language might play its
extraordinary part in its operation upon men’s thoughts, actions,
institutions, and fortunes?
The vibrations of an elastic fluid like the air, and their
properties, follow from the laws of motion; and whether or not
these laws of the motion of fluids might in reality have been other
than they are, they appear to us inseparably connected with the
existence of matter, and as much a thing of necessity as we can
conceive any thing in the universe to be. The propagation of such
vibrations, therefore, and their properties, we may at present
allow to be a necessary part of the constitution of the atmosphere.
But what is it that makes these vibrations become sound? How is it
that they produce such an effect on our senses, and, through those,
on our minds? The vibrations of the air seem to be of themselves
no more fitted to produce sound, than to produce smell. We know
that such vibrations do not universally produce sound, but only
between certain limits. When the vibrations are fewer than eighty
in a second, they are perceived as separate throbs, and not as a
continued sound; and there is a certain limit of rapidity, beyond
which the vibrations become inaudible. This limit is different to
different ears, and we are thus assured by one person’s ear that
there are vibrations, though to that of another they do not produce
sound. How was the human ear adapted so that its perception of
vibrations as sounds should fall within these limits?--the very
limits within which the vibrations fall, which it most concerns
us to perceive: those of the human voice for instance? How nicely
are the organs adjusted with regard to the most minute mechanical
motions of the elements?
CHAPTER XV.
_The Atmosphere._
We have considered in succession a number of the properties and
operations of the atmosphere, and have found them separately very
curious. But an additional interest belongs to the subject when we
consider them as combined. The atmosphere under this point of view
must appear a contrivance of the most extraordinary kind. To answer
any of its purposes, to carry on any of its processes, separately,
requires peculiar arrangements and adjustments; to answer, all at
once, purposes so varied, to combine without confusion so many
different trains, implies powers and attributes which can hardly
fail to excite in a high degree our admiration and reverence.
If the atmosphere be considered as a vast machine, it is
difficult to form any just conception of the profound skill and
comprehensiveness of design which it displays. It diffuses and
tempers the heat of different climates; for this purpose it
performs a circulation occupying the whole range from the pole to
the equator; and while it is doing this, it executes many smaller
circuits between the sea and the land. At the same time, it is
the means of forming clouds and rain, and for this purpose, a
perpetual circulation of the watery part of the atmosphere goes on
between its lower and upper regions. Besides this complication of
circuits, it exercises a more irregular agency, in the occasional
winds which blow from all quarters, tending perpetually to restore
the equilibrium of heat and moisture. But this incessant and
multiplied activity discharges only a part of the functions of the
air. It is, moreover, the most important and universal material of
the growth and sustenance of plants and animals; and is for this
purpose every where present and almost uniform in its quantity.
With all its local motion, it has also the office of a medium
of communication between intelligent creatures, which office it
performs by another set of motions, entirely different both from
the circulation and the occasional movements already mentioned;
these different kinds of motions not interfering materially with
each other: and this last purpose, so remote from the others
in its nature, it answers in a manner so perfect and so easy,
that we cannot imagine that the object could have been more
completely attained, if this had been the sole purpose for which
the atmosphere had been created. With all these qualities, this
extraordinary part of our terrestrial system is scarcely ever in
the way: and when we have occasion to do so, we put forth our hand
and push it aside, without being aware of its being near us.
We may add, that it is, in addition to all that we have hitherto
noticed, a constant source of utility and beauty in its effects
on light. Without air we should see nothing, except objects on
which the sun’s rays fell, directly or by reflection. It is the
atmosphere which converts sunbeams into daylight, and fills the
space in which we are with illumination.
The contemplation of the atmosphere, as a machine which answers all
these purposes, is well suited to impress upon us the strongest
conviction of the most refined, far-seeing, and far-ruling
contrivance. It seems impossible to suppose that these various
properties were so bestowed and so combined, any otherwise than by
a beneficent and intelligent Being, able and willing to diffuse
organization, life, health, and enjoyment through all parts of
the visible world; possessing a fertility of means which no
multiplicity of objects could exhaust, and a discrimination of
consequences which no complication of conditions could embarrass.
CHAPTER XVI.
_Light._
Besides the hearing and sound there is another mode by which we
become sensible of the impressions of external objects, namely,
sight and light. This subject also offers some observations bearing
on our present purpose.
It has been declared by writers on Natural Theology, that the
human eye exhibits such evidence of design and skill in its
construction, that no one, who considers it attentively, can resist
this impression: nor does this appear to be saying too much. It
must, at the same time, be obvious that this construction of the
eye could not answer its purposes, except the constitution of light
corresponded to it. Light is an element of the most peculiar kind
and properties, and such an element can hardly be conceived to have
been placed in the universe without a regard to its operation and
functions. As the eye is made for light, so light must have been
made, at least among other ends, for the eye.
1. We must expect to comprehend imperfectly only the mechanism
of the elements. Still, we have endeavoured to show that in some
instances the arrangements by which their purposes are effected
are, to a certain extent, intelligible. In order to explain,
however, in what manner light answers those ends which appear to us
its principal ones, we must know something of the nature of light.
There have, hitherto, been, among men of science, two prevailing
opinions upon this subject: some considering light as consisting
in the emission of luminous particles; others accounting for
its phenomena by the propagation of vibrations through a highly
subtle and elastic _ether_. The former opinion has, till lately,
been most generally entertained in this country, having been the
hypothesis on which Newton made his calculations; the latter is
the one to which most of those persons have been led, who, in
recent times, have endeavoured to deduce general conclusions from
the newly discovered phenomena of light. Among these persons, the
_theory of undulations_ is conceived to be established in nearly
the same manner, and almost as certainly, as the doctrine of
universal gravitation; namely, by a series of laws inferred from
numerous facts, which, proceeding from different sets of phenomena,
are found to converge to one common view; and by calculations
founded upon the theory, which, indicating new and untried facts,
are found to agree exactly with experiment.
We cannot here introduce a sketch of the progress by which the
phenomena have thus led to the acceptance of the theory of
undulations. But this theory appears to have such claims to our
assent, that the views which we have to offer with regard to the
design exercised in the adaptation, of light to its purposes, will
depend on the undulatory theory, so far as they depend on theory at
all.[15]
2. The impressions of sight, like those of hearing, differ in
intensity and in kind. _Brightness_ and _Colour_ are the principal
differences among visible things, as loudness and pitch are among
sounds. But there is a singular distinction between these senses
in one respect: every object and part of an object seen, is
necessarily and inevitably referred to some _position_ in the space
before us; and hence visible things have place, magnitude, form,
as well as light, shade, and colour. There is nothing analogous
to this in the sense of hearing; for though we can, in some
approximate degree, _guess_ the situation of the point from which
a sound proceeds, this is a secondary process, distinguishable from
the perception of the sound itself; whereas we cannot conceive
visible things without form and place.
The law according to which the sense of vision is thus affected,
appears to be this. By the properties of light, the external scene
produces, through the transparent parts of the eye, an image or
picture exactly resembling the reality, upon the back part of the
retina: and each point which we see, is seen in the direction of a
line passing from its image on the retina, through the centre of
the pupil of the eye.[16] In this manner we perceive by the eye the
situation of every point, at the same time that we perceive its
existence; and by combining the situations of many points, we have
forms and outlines of every sort.
That we should receive from the eye this notice of the position
of the object as well as of its other visible qualities, appears
to be absolutely necessary for our intercourse with the external
world; and the faculty of doing so is so intimate a part of our
constitution that we cannot conceive ourselves divested of it.
Yet in order to imagine ourselves destitute of this faculty, we
have only to suppose that the eye should receive its impressions
as the ear does, and should apprehend red and green, bright and
dark, without placing them side by side; as the ear takes in the
different sounds which compose a concert, without attributing them
to different parts of space.
The peculiar property thus belonging to vision, of perceiving
position, is so essential to us, that we may readily believe that
some particular provision has been made for its existence. The
remarkable mechanism of the eye (precisely resembling that of a
_camera obscura_,) by which it produces an image on the nervous
web forming its hinder part, seems to have this effect for its
main object. And this mechanism necessarily supposes certain
corresponding properties in light itself, by means of which such an
effect becomes possible.
The main properties of light which are concerned in this
arrangement, are _reflexion_ and _refraction_: reflexion by which
light is reflected and scattered by all objects, and thus comes to
the eye from all: and refraction, by which its course is bent, when
it passes obliquely out of one transparent medium into another;
and by which, consequently, convex transparent substances, such as
the cornea and humours of the eye, possess the power of making the
light converge to a _focus_ or point; an assemblage of such points
forming the images on the retina, which we have mentioned.
Reflexion and refraction are therefore the essential and
indispensable properties of light; and so far as we can understand,
it appears that it was necessary that light should possess such
properties, in order that it might form a medium of communication
between man and the external world. We may consider its power of
passing through transparent media (as air) to be given in order
that it may enlighten the earth; its affection of reflexion, for
the purpose of making colours visible; and its refraction to
be bestowed, that it may enable us to discriminate figure and
position, by means of the lenses of the eye.
In this manner light may be considered as constituted with a
peculiar reference to the eyes of animals, and its leading
properties may be looked upon as contrivances or adaptations to
fit it for its visual office. And in such a point of view the
perfection of the contrivance or adaptation must be allowed to be
very remarkable.
3. But besides the properties of reflexion and refraction, the most
obvious laws of light, an extraordinary variety of phenomena have
lately been discovered, regulated by other laws of the most curious
kind, uniting great complexity with great symmetry. We refer to the
phenomena of diffraction, polarisation, and periodical colours,
produced by crystals and by thin plates. We have, in these facts,
a vast mass of properties and laws, offering a subject of study
which has been pursued with eminent skill and intelligence. But
these properties and laws, so far as has yet been discovered,
exert no agency whatever, and have no purpose, in the general
economy of nature. Beams of light polarised in contrary directions
exhibit the most remarkable differences when they pass through
certain crystals, but manifest no discoverable difference in their
immediate impression on the eye. We have, therefore, here, a number
of laws of light, which we cannot perceive to be established with
any design which has a reference to the other parts of the universe.
Undoubtedly it is exceedingly possible that these differences of
light may operate in some quarter, and in some way, which we cannot
detect; and that these laws may have purposes and may answer ends
of which we have no suspicion. All the analogy of nature teaches
us a lesson of humility, with regard to the reliance we are to
place on our discernment and judgment as to such matters. But with
our present knowledge, we may observe, that this curious system of
phenomena appears to be a collateral result of the mechanism by
which the effects of light are produced; and therefore a necessary
consequence of the existence of that element of which the offices
are so numerous and so beneficent.
The new properties of light, and the speculations founded upon
them, have led many persons to the belief of the undulatory theory;
which, as we have said, is considered by some philosophers as
demonstrated. If we adopt this theory, we consider the luminiferous
ether to have no local motion; and to produce refraction and
reflexion by the operation of its elasticity alone. We must
necessarily suppose the tenuity of the ether to be extreme; and
if we moreover suppose its tension to be very great, which the
vast velocity of light requires us to suppose, the vibrations by
which light is propagated will be _transverse_ vibrations, that
is the motion to and fro will be athwart the line along which the
undulation travels; and from this circumstance all the laws of
polarisation necessarily follow. And the properties of transverse
vibrations, combined with the properties of vibrations in general,
give rise to all the curious and numerous phenomena of colours of
which we have spoken.
If the vibrations be transverse, they may be resolved into two
different planes; this is _polarisation_: if they fall on a
medium which has different elasticity in different directions,
they will be divided into two sets of vibrations; this is _double
refraction_; and so on. Some of the new properties, however, as the
fringes of shadows and the colours of thin plates, follow from the
undulatory theory, whether the vibrations be transverse or not.
It would appear, therefore, that the propagation of light by
means of a subtle medium, leads necessarily to the extraordinary
collection of properties which have recently been discovered; and,
at any rate, its propagation by the transverse vibrations of such a
medium does lead inevitably to these results.
Leaving it therefore to future times to point out the other reasons
(or _uses_ if they exist) of these newly discovered properties of
light, in their bearing on other parts of the world, we may venture
to say, that if light was to be propagated through transparent
media by the undulations of a subtle fluid, these properties must
result, as necessarily as the rainbow results from the unequal
refrangibility of different colours. This phenomenon and those,
appear alike to be the collateral consequences of the law’s
impressed on light with a view to its principal offices.
Thus the exquisitely beautiful and symmetrical phenomena and laws
of polarisation, and of crystalline and other effects, may be
looked upon as indications of the delicacy and subtlety of the
mechanism by which man, through his visual organs, is put in
communication with the external world; is made acquainted with the
forms and qualities of objects in the most remote regions of space;
and is enabled, in some measure, to determine his position and
relation in a universe in which he is but an atom.
4. If we suppose it clearly established that light is produced
by the vibrations of an ether, we find considerations offer
themselves, similar to those which occurred in the case of sound.
The vibrations of this ether affect our organs with the sense of
light and colour. Why, or how do they do this? It is only within
certain limits that the effect is produced, and these limits are
comparatively narrower here than in the case of sound. The whole
scale of colour, from violet to crimson, lies between vibrations
which are four hundred and fifty-eight million millions, and seven
hundred and twenty-seven million millions in a second; a proportion
much smaller than the corresponding ratio for perceptible sounds.
Why should such vibrations produce perception in the eye, and
no others? There must be here some peculiar adaptation of the
sensitive powers to these wonderfully minute and condensed
mechanical motions. What happens when the vibrations are slower
than the red, or quicker than the blue? They do not produce vision:
do they produce any effect? Have they any thing to do with heat or
with electricity? We cannot tell. The ether must be as susceptible
of these vibrations, as of those which produce vision. But the
mechanism of the eye is adjusted to this latter kind only; and this
precise kind, (whether alone or mixed with others,) proceeds from
the sun and from other luminaries, and thus communicates to us the
state of the visible universe. The mere material elements then are
full of properties which we can understand no otherwise, than as
the results of a refined contrivance.
CHAPTER XVII.
_The Ether._
In what has just been said, we have spoken of light, only with
respect to its power of illuminating objects, and conveying the
impression of them to the eye. It possesses, however, beyond all
doubt, many other qualities. Light is intimately connected with
heat, as we see in the case of the sun and of flame; yet it is
clear that light and heat are not identical. Light is evidently
connected too with electricity and galvanism; and perhaps, through
these, with magnetism: it is, as has already been mentioned,
indispensably necessary to the healthy discharge of the functions
of vegetable life; without it plants cannot duly exercise their
vital powers: it manifests also chemical action in various ways.
The luminiferous _ether_ then, if we so call the medium in which
light is propagated, must possess many other properties besides
those mechanical ones on which the illuminating power depends. It
must not be merely like a fluid poured into the vacant spaces and
interstices of the material world, and exercising no action on
objects; it must affect the physical, chemical and vital powers of
what it touches. It must be a great and active agent in the work
of the universe, as well as an active reporter of what is done
by other agents. It must possess a number of complex and refined
contrivances and adjustments which we cannot analyze, bearing upon
plants and chemical compounds, and the imponderable agents; as well
as those laws which we conceive that we have analyzed, by which it
is the vehicle of illumination and vision.
We have had occasion to point out how complex is the machinery of
the atmosphere, and how varied its objects; since, besides being
the means of communication as the medium of sound, it has known
laws which connect it with heat and moisture; and other laws, in
virtue of which it is decomposed by vegetables. It appears, in
like manner, that the ether is not only the vehicle of light,
but has also laws, at present unknown, which connect it with
heat, electricity, and other agencies; and other laws through
which it is necessary to vegetables, enabling them to decompose
air. All analogy leads us to suppose that if we knew as much of
the constitution of the luminiferous ether as we know of the
constitution of the atmosphere, we should find it a machine as
complex and artificial, as skilfully and admirably constructed.
We know at present very little indeed of the construction of this
machine. Its _existence_ is, perhaps, satisfactorily made out;
in order that we may not interrupt the progress of our argument,
we shall refer to other works for the reasonings which appear to
lead to this conclusion. But whether heat, electricity, galvanism,
magnetism, be fluids; or effects or modifications of fluids; and
whether such fluids or _ethers_ be the same with the luminiferous
ether, or with each other; are questions of which all or most
appear to be at present undecided, and it would be presumptuous and
premature here to take one side or the other.
The mere fact, however, that there is such an ether, and that
it has properties related to other agents, in the way we have
suggested, is well calculated to extend our views of the structure
of the universe, and of the resources, if we may so speak, of the
Power by which it is arranged. The solid and fluid matter of the
earth is the most obvious to our senses; over this, and in its
cavities, is poured an invisible fluid, the air, by which warmth
and life are diffused and fostered, and by which men communicate
with men: over and through this again, and reaching, so far as we
know, to the utmost bounds of the universe, is spread another most
subtle and attenuated fluid, which, by the play of another set of
agents, aids the energies of nature, and which, filling all parts
of space, is a means of communication with other planets and other
systems.
There is nothing in all this like any material necessity,
compelling the world to be as it is and no otherwise. How should
the properties of these three great classes of agents, visible
objects, air, and light, so harmonize and assist each other, that
order and life should be the result. Without all the three, and
all the three constituted in their present manner, and subject to
their present laws, living things could not exist. If the earth had
no atmosphere, or if the world had no ether, all must be inert and
dead. Who constructed these three extraordinary complex pieces of
machinery, the earth with its productions, the atmosphere, and the
ether? Who fitted them into each other in many parts, and thus made
it possible for them to work together? We conceive there can be but
one answer; a most wise and good God.
CHAPTER XVIII.
_Recapitulation._
1. It has been shown in the preceding chapters that a great number
of quantities and laws appear to have been _selected_ in the
construction of the universe; and that by the adjustment to each
other of the magnitudes and laws thus selected, the constitution
of the world is what we find it, and is fitted for the support
of vegetables and animals, in a manner in which it could not have
been, if the properties and quantities of the elements had been
different from what they are. We shall here recapitulate the
principal of the laws and magnitudes to which this conclusion has
been shown to apply.
1. The Length of the Year, which depends on the force of the
attraction of the sun, and its distance from the earth.
2. The Length of the Day.
3. The Mass of the Earth, which depends on its magnitude and
density.
4. The Magnitude of the Ocean.
5. The Magnitude of the Atmosphere.
6. The Law and Rate of the Conducting Power of the Earth.
7. The Law and Rate of the Radiating Power of the Earth.
8. The Law and Rate of the Expansion of Water by Heat.
9. The Law and Rate of the Expansion of Water by Cold, below 40
degrees.
10. The Law and Quantity of the Expansion of Water in Freezing.
11. The Quantity of Latent Heat absorbed in Thawing.
12. The Quantity of Latent Heat absorbed in Evaporation.
13. The Law and Rate of Evaporation with regard to Heat.
14. The Law and Rate of the Expansion of Air by Heat.
15. The Quantity of Heat absorbed in the Expansion of Air.
16. The Law and Rate of the Passage of Aqueous Vapour through Air.
17. The Laws of Electricity; its relations to Air and Moisture.
18. The Fluidity, Density, and Elasticity of the Air, by means of
which its vibrations produce Sound.
19. The Fluidity, Density, and Elasticity of the Ether, by means
of which its vibrations produce Light.
2. These are the _data_, the _elements_, as astronomers call
the quantities which determine a planet’s orbit, on which the
mere _inorganic_ part of the universe is constructed. To these,
the constitution of the organic world is adapted in innumerable
points, by laws of which we can trace the results, though we cannot
analyze their machinery. Thus, the vital functions of vegetables
have periods which correspond to the length of the year, and of
the day; their vital powers have forces which correspond to the
force of gravity; the sentient faculties of man are such that
the vibrations of air (within certain limits,) are perceived as
sound, those of ether, as light. And while we are enumerating these
correspondencies, we perceive that there are thousands of others,
and that we can only select a very small number of those where
the relation happens to be most clearly made out or most easily
explained.
Now, in the list of the mathematical _elements_ of the universe
which has just been given, why have we such laws and such
quantities as there occur, and no other? For the most part, the
data there enumerated are independent of each other, and might be
altered separately, so far as the mechanical conditions of the case
are concerned. Some of these data probably depend on each other.
Thus the latent heat of aqueous vapour is perhaps connected with
the difference of the rate of expansion of water and of steam. But
all natural philosophers will, probably, agree, that there must be,
in this list, a great number of things entirely without any mutual
dependence, as the year and the day, the expansion of air and the
expansion of steam. There are, therefore, it appears, a number
of things which, in the structure of the world, might have been
otherwise, and which are what they are in consequence of choice or
of chance. We have already seen, in many of the cases separately,
how unlike chance every thing looks:--that substances, which might
have existed any how, so far as they themselves are concerned,
exist exactly in such a manner and measure as they should, to
secure the welfare of other things:--that the laws are tempered
and fitted together in the only way in which the world could have
gone on, according to all that we can conceive of it. This must,
therefore, be the work of choice; and if so, it cannot be doubted,
of a most wise and benevolent Chooser.
3. The appearance of choice is still further illustrated by the
variety as well as the number of the laws selected. The laws are
unlike one another. Steam certainly expands at a very different
_rate_ from air by the application of heat, probably according to a
different _law_: water expands in freezing, but mercury contracts:
heat travels in a manner quite different through solids and fluids.
Every separate substance has its own density, gravity, cohesion,
elasticity, its relations to heat, to electricity, to magnetism;
besides all its chemical affinities, which form an endless throng
of laws, connecting every one substance in creation with every
other, and different for each pair anyhow taken. Nothing can
look less like a world formed of atoms operating upon each other
according to some universal and inevitable laws, than this does: if
such a system of things be conceivable, it cannot be our system.
We have, it may be, fifty simple substances in the world; each of
which is invested with properties, both of chemical and mechanical
action, altogether different from those of any other substance.
Every portion, however minute, of any of these, possesses all
the properties of the substance. Of each of these substances
there is a certain unalterable quantity in the universe; when
combined, their compounds exhibit new chemical affinities, new
mechanical laws. Who gave these different laws to the different
substances? who proportioned the quantity of each? But suppose
this done. Suppose these substances in existence; in contact, in
due proportion to each other. Is _this_ a world, or at least our
world? No more than the mine and the forest are the ship of war and
the factory. These elements, with their constitution perfect, and
their proportion suitable, are still a mere chaos. They must be put
in their places. They must not be where their own properties would
place them. They must be made to assume a particular arrangement,
or we can have no regular and permanent course of nature. This
arrangement must again have additional peculiarities, or we can
have no organic portion of the world. The millions of millions
of particles which the world contains, must be finished up in
as complete a manner, and fitted into their places with as much
nicety, as the most delicate wheel or spring in a piece of human
machinery. What are the habits of thought to which it can appear
possible that this could take place without design, intention,
intelligence, purpose, knowledge?
In what has just been said, we have spoken only of the constitution
of the inorganic part of the universe. The mechanism, if we may
so call it, of vegetable and animal life, is so far beyond our
comprehension, that though some of the same observations might be
applied to it, we do not dwell upon the subject. We know that in
these processes also, the mechanical and chemical properties of
matter are necessary, but we know too that these alone will not
account for the phenomena of life. There is something more than
these. The lowest stage of vitality and irritability appears to
carry us beyond mechanism, beyond affinity. All that has been said
with regard to the exactness of the adjustments, the combination of
various means, the tendency to continuance, to preservation, is
applicable with additional force to the organic creation, so far
as we can perceive the means employed. These, however, belong to a
different province of the subject, and must be left to other hands.
BOOK II.
COSMICAL ARRANGEMENTS.
When we turn our attention to the larger portions of the universe,
the sun, the planets, and the earth as one of them, the moon and
other satellites, the fixed stars and other heavenly bodies;--the
views which we obtain concerning their mutual relations,
arrangement and movements, are called, as we have already
stated, _cosmical_ views. These views will, we conceive, afford
us indications of the wisdom and care of the Power by which the
objects which we thus consider, were created and are preserved: and
we shall now proceed to point out some circumstances in which these
attributes may be traced.
It has been observed by writers on Natural Theology, that the
arguments for the being and perfections of the Creator, drawn
from cosmical considerations, labour under some disadvantages
when compared with the arguments founded on those provisions
and adaptations which more immediately affect the well-being of
organized creatures. The structure of the solar system has far less
analogy with such machinery as we can construct and comprehend,
than we find in the structure of the bodies of animals, or even in
the causes of the weather. Moreover, we do not see the immediate
bearing of cosmical arrangements on that end which we most readily
acknowledge to be useful and desirable, the support and comfort
of sentient natures. So that, from both causes, the impression of
benevolent design in this case is less striking and pointed than
that which results from the examination of some other parts of
nature.
But in considering the universe, according to the view we have
taken, as a collection of _laws_, astronomy, the science which
teaches us the laws of the motions of the heavenly bodies,
possesses some advantages, among the subjects from which we may
seek to learn the character of the government of the world. For our
knowledge of the laws of the motions of the planets and satellites
is far more complete and exact, far more thorough and satisfactory,
than the knowledge which we possess in any other department of
Natural Philosophy. Our acquaintance with the laws of the solar
system is such, that we can calculate the precise place and motion
of most of its parts at any period, past or future, however
remote; and we can refer the changes which take place in these
circumstances to their proximate cause, the attraction of one mass
of matter to another, acting between all the parts of the universe.
If, therefore, we trace indications of the Divine care, either in
the form of the laws which prevail among the heavenly bodies, or
in the arbitrary quantities which such laws involve; (according
to the distinction explained in the former part of this work;) we
may expect that our examples of such care, though they may be less
numerous and obvious, will be more precise than they can be in
other subjects, where the laws of facts are imperfectly known, and
their causes entirely hid. We trust that this will be found to be
the case with regard to some of the examples which we shall adduce.
CHAPTER I.
_The Structure of the Solar System._
In the cosmical considerations which we have to offer, we shall
suppose the general truths concerning the structure of the solar
system and of the universe, which have been established by
astronomers and mathematicians, to be known to the reader. It is
not necessary to go into much detail on this subject. The five
planets known to the ancients, Mercury, Venus, Mars, Jupiter,
Saturn, revolve round the sun, at different distances, in orbits
nearly circular, and nearly in one plane. Between Venus and Mars,
our Earth, herself one of the planets, revolves in like manner.
Beyond Saturn, Uranus has been discovered describing an orbit of
the same kind; and between Mars and Jupiter, four smaller bodies
perform their revolutions in orbits somewhat less regular than
the rest. These planets are all nearly globular, and all revolve
upon their axis. Some of them are accompanied by satellites, or
attendant bodies which revolve about them; and these bodies also
have their orbits nearly circular, and nearly in the same plane as
the others. Saturn’s ring is a solitary example, so far as we know,
of such an appendage to a planet.
These circular motions of the planets round the sun, and of the
satellites round their primary planets, are all kept going by the
_attraction_ of the respective central bodies, which restrains the
corresponding revolving bodies from flying off. It is perhaps not
very easy to make this operation clear to common apprehension. We
cannot illustrate it by a comparison with any machine of human
contrivance and fabrication: in such machines every thing goes
on by contact and impulse: pressure, and force of all kinds, is
exercised and transferred from one part to another, by means of a
material connexion; by rods, ropes, fluids, gases. In the machinery
of the universe there is, so far as we know, no material connexion
between the parts which act on each other. In the solar system no
part touches or drives another: all the bodies affect each other
_at a distance_, as the magnet affects the needle. The production
and regulation of such effects, if attempted by our mechanicians,
would require great skill and nicety of adjustment; but our artists
have not executed any examples of this sort of machinery, by
reference to which we can illustrate the arrangements of the solar
system.
Perhaps the following comparison may serve to explain the kind of
adjustments of which we shall have to speak. If there be a wide
shallow round basin of smooth marble, and if we take a smooth ball,
as a billiard ball or a marble pellet, and throw it along the
surface of the inside of the basin, the ball will generally make
many revolutions round the inside of the bowl, gradually tending to
the bottom in its motion. The gradual diminution of the motion, and
consequent tendency of the ball to the bottom of the bowl, arises
from the friction; and in order to make the motion correspond to
that which takes place through the action of a central force,
we must suppose this friction to be got rid of. In this case,
the ball, once set a going, would run round the basin for ever,
describing either a circle, or various kinds of ovals, according to
the way in which it was originally thrown; whether quick or slow,
and whether more or less obliquely along the surface.
Such a motion would be capable of the same kind of variety, and the
same sort of adjustments, as the motion of a body revolving about
a larger one by means of a central force. Perhaps the reader may
understand what kind of adjustments these are, by supposing such a
bowl and ball to be used for a game of skill. If the object of the
players be to throw the pellet along the surface of the basin, so
that after describing its curved path it shall pass through a small
hole in a barrier at some distance from the starting point, it will
easily be understood that some nicety in the regulation of the
force and direction with which the ball is thrown will be necessary
for success. In order to obtain a better image of the solar system,
we must suppose the basin to be very large and the pellet very
small. And it will easily be understood that as many pellets as
there are planets might run round the bowl at the same time with
different velocities. Such a contrivance might form a _planetarium_
in which the mimic planets would be regulated by the laws of motion
as the real planets are; instead of being carried by wires and
wheels, as is done in such machines of the common construction:
and in this planetarium the tendency of the planets to the sun is
replaced by the tendency of the representative pellets to run down
the slope of the bowl. We shall refer again to this basin, thus
representing the solar system with its loose planetary balls.
CHAPTER II.
_The Circular Orbits of the Planets round the Sun._
The orbit which the earth describes round the sun is very nearly
a circle: the sun is about one thirtieth nearer to us in winter
than in summer. This nearly circular form of the orbit, on a little
consideration, will appear to be a remarkable circumstance.
Supposing the attraction of a planet towards the sun to exist, if
the planet were put in motion in any part of the solar system, it
would describe about the sun an orbit _of some kind_; it might
be a long oval, or a shorter oval, or an exact circle. But if
we suppose the result left to chance, the chances are infinitely
against the last mentioned case. There is but one circle; there
are an infinite number of ovals. Any original impulse would give
some oval, but only one particular impulse, determinate in velocity
and direction, will give a circle. If we suppose the planet to be
originally _projected_, it must be projected perpendicularly to
its distance from the sun, and with a certain precise velocity, in
order that the motion may be circular.
In the basin to which we have compared the solar system, the
adjustment requisite to produce circular motion would require us
to project our pellet so that after running half round the surface
it should touch a point exactly at an equal distance from the
centre, on the other side, passing neither too high nor too low.
And the pellet, it may be observed, should be in size only one
ten thousandth part of the distance from the centre, to make the
dimensions correspond with the cast of the earth’s orbit. If the
mark were set up and hit, we should hardly attribute the result to
chance.
The earth’s orbit, however, is not exactly a circle. The mark is
not precisely a single point, but is a space of the breadth of one
thirtieth of the distance from the centre. Still this is much too
near an agreement with the circle to be considered as the work of
chance. The chances were great against the ball passing so nearly
at the same distance, for there were twenty-nine equal spaces
through which it might have gone, between the mark and the centre,
and an indefinite number outside the mark.
But it is not the earth’s orbit alone which is nearly a circle:
the rest of the planets also approach very nearly to that form:
Venus more nearly still than the earth: Jupiter, Saturn, and Uranus
have a difference of about one tenth, between their greatest and
least distances from the sun: Mars has his extreme distances in the
proportion of five to six nearly; and Mercury in the proportion of
two to three. The last mentioned case is a considerable deviation,
and two of the small planets which lie between Mars and Jupiter,
namely Juno and Pallas, exhibit an inequality somewhat greater
still; but the smallness of these bodies, and other circumstances,
make it probable that there may be particular causes for the
exception in their case. The orbits of the satellites of the Earth,
of Jupiter and of Saturn, are also nearly circular.
Taking the solar system altogether, the regularity of its structure
is very remarkable. The diagram which represents the orbits of the
planets might have consisted of a number of ovals, narrow and wide
in all degrees, intersecting and interfering with each other in
all directions. The diagram does consist, as all who have opened a
book of astronomy know, of a set of figures which appear at first
sight concentric circles, and which are very nearly so; no where
approaching to any crossing or interfering, except in the case of
the small planets, already noticed as irregular. No one, looking at
this common diagram, can believe that the orbits were made to be
so nearly circles by chance; any more than he can believe that a
target, such as archers are accustomed to shoot at, was painted in
concentric circles by the accidental dashes of a brush in the hands
of a blind man.
The regularity, then, of the solar system excludes the notion of
accident in the arrangement of the orbits of the planets. There
must have been an express adjustment to produce this circular
character of the orbits. The velocity and direction of the motion
of each planet must have been subject to some original regulation;
or, as it is often expressed, the projectile force must have been
accommodated to the centripetal force. This once done, the motion
of each planet, taken by itself, would go on for ever, still
retaining its circular character, by the laws of motion.
If some original cause adjusted the orbits of the planets to
their circular form and regular arrangement, we can hardly avoid
including in our conception of this cause, the intention and will
of a Creating Power. We shall consider this argument more fully
in a succeeding chapter; only observing here, that the presiding
Intelligence, which has selected and combined the properties of the
organic creation, so that they correspond so remarkably with the
arbitrary quantities of the system of the universe, may readily
be conceived also to have selected the arbitrary velocity and
direction of each planet’s motion, so that the adjustment should
produce a close approximation to a circular motion.
We have argued here only from the _regularity_ of the solar
system; from the selection of the single symmetrical case and the
rejection of all the unsymmetrical cases. But this subject may be
considered in another point of view. The system thus selected is
not only regular and symmetrical, but also it is, so far as we can
judge, the only one which would answer the purpose of the earth,
perhaps of the other planets, as the seat of animal and vegetable
life. If the earth’s orbit were more eccentric, as it is called,
if for instance the greatest and least distances were as three
to one, the inequality of heat at two seasons of the year would
be destructive to the existing species of living creatures. A
circular, or nearly circular, orbit, is the only case in which we
can have a course of seasons such as we have at present, the only
case in which the climates of the northern and southern hemispheres
are nearly the same; and what is more clearly important, the only
case in which the character of the seasons would not vary from
century to century. For if the eccentricity of the earth’s orbit
were considerable, the difference of heat at different seasons,
arising from the different distances of the sun, would be combined
with the difference, now the only considerable one, which depends
on the position of the earth’s axis. And as by the motion of
the _perihelion_, or place of the nearest distance of the earth
to the sun, this nearest distance would fall in different ages
at different parts of the year, the whole distribution of heat
through the year would thus be gradually subverted. The summer and
winter of the _tropical_ year, as we have it now, being combined
with the heat and cold of the _anomalistic_ year, a period of
different length, the difference of the two seasons might sometimes
be neutralized altogether, and at other times exaggerated by the
accumulation of the inequalities, so as to be intolerable.
The circular form of the orbit therefore, which, from its unique
character, appears to be chosen with _some_ design, from its
effects on the seasons appears to be chosen with this design,
so apparent in other parts of creation, of securing the welfare
of organic life, by a steadfast and regular order of the solar
influence upon the planet.
CHAPTER III.
_The Stability of the Solar System._
There is a consequence resulting from the actual structure of the
solar system, which has been brought to light by the investigations
of mathematicians concerning the cause and laws of its motions, and
which has an important bearing on our argument. It appears that the
arrangement which at present obtains is precisely that which is
necessary to secure the _stability_ of the system. This point we
must endeavour to explain.
If each planet were to revolve round the sun without being affected
by the other planets, there would be a certain degree of regularity
in its motion; and this regularity would continue for ever. But it
appears, by the discovery of the law of universal gravitation,
that the planets do not execute their movements in this insulated
and independent manner. Each of them is acted on by the attraction
of all the rest. The Earth is constantly drawn by Venus, by Mars,
by Jupiter, bodies of various magnitudes, perpetually changing
their distances and positions with regard to the earth; the Earth
in return is perpetually drawing these bodies. What, in the course
of time, will be the result of this mutual attraction?
All the planets are very small compared with the sun, and therefore
the derangement which they produce in the motion of one of their
number will be very small in the course of one revolution. But this
gives us no security that the derangement may not become very large
in the course of many revolutions. The cause acts perpetually,
and it has the whole extent of time to work in. Is it not easily
conceivable then that in the lapse of ages the derangements of
the motions of the planets may accumulate, the orbits may change
their form, their mutual distances may be much increased or much
diminished? Is it not possible that these changes may go on without
limit, and end in the complete subversion and ruin of the system?
If, for instance, the result of this mutual gravitation should be
to increase considerably the eccentricity of the earth’s orbit,
that is to make it a longer and longer oval; or to make the moon
approach perpetually nearer and nearer the earth every revolution;
it is easy to see that in the one case our year would change its
character, as we have noticed in the last section; in the other,
our satellite might finally fall to the earth, which must of
course bring about a dreadful catastrophe. If the positions of
the planetary orbits, with respect to that of the earth, were to
change much, the planets might sometimes come very near us, and
thus exaggerate the effects of their attraction beyond calculable
limits. Under such circumstances, we might have “years of unequal
length, and seasons of capricious temperature, planets and moons of
portentous size and aspect, glaring and disappearing at uncertain
intervals;” tides like deluges, sweeping over whole continents;
and, perhaps, the collision of two of the planets, and the
consequent destruction of all organization on both of them.
Nor is it, on a common examination of the history of the solar
system, at all clear that there is no tendency to indefinite
derangement. The fact really is, that changes are taking place
in the motions of the heavenly bodies, which have gone on
progressively from the first dawn of science. The eccentricity
of the earth’s orbit has been diminishing from the earliest
observations to our times. The moon has been moving quicker and
quicker from the time of the first recorded eclipses, and is now
in advance, by about four times her own breadth, of what her place
would have been if it had not been affected by this acceleration.
The obliquity of the ecliptic also is in a state of diminution, and
is now about two-fifths of a degree less than it was in the time
of Aristotle. Will these changes go on without limit or reaction?
If so, we tend by natural causes to a termination of the present
system of things: If not, by what adjustment or combination are we
secured from such a tendency? Is the system _stable_, and if so,
what is the condition on which its stability depends?
To answer these questions is far from easy. The mechanical problem
which they involve is no less than this;--Having given the
directions and velocities with which about thirty bodies are moving
at one time, to find their places and motions after any number of
ages; each of the bodies, all the while, attracting all the others,
and being attracted by them all.
It may readily be imagined that this is a problem of extreme
complexity, when it is considered that every new _configuration_
or arrangement of the bodies will give rise to a new amount of
action on each; and every new action to a new configuration.
Accordingly, the mathematical investigation of such questions as
the above was too difficult to be attempted in the earlier periods
of the progress of Physical Astronomy. Newton did not undertake to
demonstrate either the stability or the instability of the system.
The decision of this point required a great number of preparatory
steps and simplifications, and such progress in the invention
and improvement of mathematical methods, as occupied the best
mathematicians of Europe for the greater part of last century.
But, towards the end of that time, it was shown by Lagrange and
Laplace that the arrangements of the solar system are stable: that
in the long run, the orbits and motions remain unchanged; and that
the changes in the orbits, which take place in shorter periods,
never transgress certain very moderate limits. Each orbit undergoes
deviations on this side and on that of its average state; but these
deviations are never very great, and it finally recovers from them,
so that the average is preserved. The planets produce perpetual
perturbations in each other’s motions, but these perturbations
are not indefinitely progressive, they are periodical: they reach
a _maximum_ value and then diminish. The periods which this
restoration requires are, for the most part, enormous; not less
than thousands, and, in some instances, millions of years; and
hence it is, that some of these apparent derangements have been
going on in the same direction since the beginning of the history
of the world. But the restoration is in the sequel as complete as
the derangement; and in the meantime the disturbance never attains
a sufficient amount seriously to alter the adaptations of the
system.[17]
The same examination of the subject by which this is proved, points
out also the conditions on which this stability depends. “I have
succeeded in demonstrating,” says Laplace, “that whatever be the
masses of the planets, in consequence of the fact that they all
move in the same direction, in orbits of small eccentricity, and
slightly inclined to each other--their secular inequalities are
periodical and included within narrow limits; so that the planetary
system will only oscillate about a mean state, and will never
deviate from it except by a very small quantity. The ellipses of
the planets have been, and always will be, nearly circular. The
ecliptic will never coincide with the equator, and the entire
extent of the variation in its inclination cannot exceed three
degrees.”
There exists, therefore, it appears, in the solar system, a
provision for the permanent regularity of its motions; and this
provision is found in the fact that the orbits of the planets are
nearly circular, and nearly in the same plane, and the motions all
in the same direction, namely, from west to east.[18]
Now is it probable that the occurrence of these conditions of
stability in the disposition of the solar system is the work of
chance? Such a supposition appears to be quite inadmissible. Any
one of the orbits might have had any eccentricity.[19] In that
of Mercury, where it is much the greatest, it is only one-fifth.
How came it to pass that the orbits were not more elongated? A
little more or a little less velocity in their original motions
would have made them so. They might have had any inclination to
the ecliptic from _no_ degrees to 90 degrees. Mercury, which again
deviates most widely, is inclined 7¾ degrees, Venus 3¾, Saturn
2¾, Jupiter 1½, Mars 2. How came it that their motions are thus
contained within such a narrow strip of the sky? One, or any number
of them, might have moved from east to west: none of them does so.
And these circumstances, which appear to be, each in particular,
requisite for the stability of the system and the smallness of its
disturbances, are all found in combination. Does not this imply
both clear purpose and profound skill?
It is difficult to convey an adequate notion of the extreme
complexity of the task thus executed. A number of bodies, all
attracting each other, are to be projected in such a manner that
their revolutions shall be permanent and stable, their mutual
perturbations always small. If we return to the basin with its
rolling balls, by which we before represented the solar system, we
must complicate with new conditions the trial of skill which we
supposed. The problem must now be to project at once seven such
balls, all connected by strings which influence their movements, so
that each may hit its respective mark. And we must further suppose,
that the marks are to be hit after many thousand revolutions of the
balls. No one will imagine that this could be done by accident.
In fact it is allowed by all those who have considered this
subject, that such a coincidence of the existing state with the
mechanical requisites of permanency cannot be accidental. Laplace
has attempted to calculate the probability that it is not the
result of accident. He takes into account, in addition to the
motions which we have mentioned, the revolutions of the satellites
about their primaries, and of the sun and planets about their
axes: and he finds that there is a probability, far higher than
that which we have for the greater part of undoubted historical
events, that these appearances are not the effect of chance. “We
ought, therefore,” he says, “to believe, with at least the same
confidence, that a primitive cause has directed the planetary
motions.”
The solar system is thus, by the confession of all sides,
completely different from any thing which we might anticipate from
the casual operation of its known laws. The laws of motion are no
less obeyed to the letter in the most irregular than in the most
regular motions; no less in the varied circuit of the ball which
flies round a tennis court, than in the going of a clock; no less
in the fantastical jets and leaps which breakers make when they
burst in a corner of a rocky shore, than in the steady swell of the
open sea. The laws of motion alone will not produce the regularity
which we admire in the motions of the heavenly bodies. There must
be an original adjustment of the system on which these laws are
to act; a selection of the arbitrary quantities which they are to
involve; a primitive cause which shall dispose the elements in
due relation to each other, in order that regular recurrence may
accompany constant change; that perpetual motion may be combined
with perpetual stability; that derangements which go on increasing
for thousands or for millions of years may finally cure themselves;
and that the same laws which lead the planets slightly aside from
their paths, may narrowly limit their deviations, and bring them
back from their almost imperceptible wanderings.
If a man does not deny that any possible peculiarity in the
disposition of the planets with regard to the sun could afford
evidence of a controlling and ordering purpose, it seems difficult
to imagine how he could look for evidence stronger than that
which there actually is. Of all the innumerable possible cases of
systems, governed by the existing laws of force and motion, that
one is selected which alone produces such a steadfast periodicity,
such a constant average of circumstances, as are, so far as we can
conceive, necessary conditions for the existence of organic and
sentient life. And this selection is so far from being an obvious
or easily discovered means to this end, that the most profound and
attentive consideration of the properties of space and number, with
all the appliances and aids we can obtain, are barely sufficient to
enable _us_ to see that the end is thus secured, and that it can be
secured in no other way. Surely the obvious impression which arises
from this view of the subject is, that the solar system, with
its adjustments, is the work of an intelligence, who perceives,
as self-evident, those truths, to which we attain painfully and
slowly, and after all imperfectly; who has employed in every part
of creation refined contrivances, which we can only with effort
understand; and who, in innumerable instances, exhibits to us what
we should look upon as remarkable difficulties remarkably overcome,
if it were not that, through the perfection of the provision, the
trace of the difficulty is almost obliterated.
CHAPTER IV.
_The Sun in the Centre._
The next circumstance which we shall notice as indicative of design
in the arrangement of the material portions of the solar system,
is the position of the sun, the source of light and heat, in the
centre of the system. This could hardly have occurred by any
thing which we can call chance. Let it be granted, that the law of
gravitation is established, and that we have a large mass, with
others much smaller in its comparative vicinity. The small bodies
may then move round the larger, but this will do nothing towards
making it a _sun_ to them. Their motions might take place, the
whole system remaining still utterly dark and cold, without day or
summer. In order that we may have something more than this blank
and dead assemblage of moving clods, the machine must be lighted
up and warmed. Some of the advantages of placing the lighting
and warming apparatus in the centre are obvious to us. It is in
this way only that we could have those regular periodical returns
of solar influence, which, as we have seen, are adapted to the
constitution of the living creation. And we can easily conceive,
that there may be other incongruities in a system with a travelling
sun, of which we can only conjecture the nature. No one probably
will doubt that the existing system, with the sun in the centre, is
better than any one of a different kind would be.
Now this lighting and warming by a central sun are something
superadded to the mere mechanical arrangements of the universe.
There is no apparent reason why the largest mass of gravitating
matter should diffuse inexhaustible supplies of light and heat in
all directions, while the other masses are merely passive, with
respect to such influences. There is no obvious connexion between
mass and luminousness, or temperature. No one, probably, will
contend that the materials of our system are necessarily luminous
or hot. According to the conjectures of astronomers, the heat and
light of the sun do not reside in its mass, but in a coating which
lies on its surface. If such a coating were fixed there by the
force of universal gravitation, how could we avoid having a similar
coating on the surface of the earth, and of all the other globes of
the system. If light consist in the vibrations of an ether, which
we have mentioned as a probable opinion, why has the sun alone the
power of exciting such vibrations? If light be the emission of
material particles, why does the sun alone emit such particles?
Similar questions may be asked, with regard to heat, whatever be
the theory we adopt on that subject. Here then we appear to find
marks of contrivance. The sun might become, we will suppose, the
centre of the motions of the planets by mere mechanical causes:
but what caused the centre of their motions to be also the source
of those vivifying influences? Allowing that no interposition was
requisite to regulate the revolutions of the system, yet observe
what a peculiar arrangement in other respects was necessary, in
order that these revolutions might produce days and seasons! The
machine will move of itself, we may grant: but who constructed the
machine, so that its movements might answer the purposes of life?
How was the candle placed upon the candlestick? How was the fire
deposited on the hearth, so that the comfort and well-being of the
family might be secured? Did these too fall into their places by
the casual operation of gravity? And, if not, is there not here
a clear evidence of intelligent design, of arrangement with a
benevolent end?
This argument is urged with great force by Newton himself. In his
first letter to Bentley, he allows that matter might form itself
into masses by the force of attraction. “And thus,” says he, “might
the sun and fixed stars be formed, supposing the matter were of
a lucid nature. But how the matter should divide itself into two
sorts; and that part of it which is fit to compose a shining body
should fall down into one mass, and make a sun; and the rest, which
is fit to compose an opaque body, should coalesce, not into one
great body, like the shining matter, but into many little ones; or
if the sun at first were an opake body like the planets, or the
planets lucid bodies like the sun, how he alone should be changed
into a shining body, whilst all they continue opake; or all they
be changed into opake ones, while he continued unchanged: I do not
think explicable by mere natural causes, but am forced to ascribe
it to the counsel and contrivance of a voluntary Agent.”
CHAPTER V.
_The Satellites._
1. A person of ordinary feelings, who, on a fine moonlight night,
sees our satellite pouring her mild radiance on field and town,
path and moor, will probably not only be disposed to “bless the
useful light,” but also to believe that it was “ordained” for that
purpose;--that the lesser light was made to rule the night as
certainly as the greater light was made to rule the day.
Laplace, however, does not assent to this belief. He observes,
that “some partisans of final causes have imagined that the moon
was given to the earth to afford light during the night:” but he
remarks that this cannot be so, for that we are often deprived at
the same time of the light of the sun and the moon; and he points
out how the moon might have been placed so as to be always “full.”
That the light of the moon affords, _to a certain extent_, a
supplement to the light of the sun, will hardly be denied. If
we take man in a condition in which he uses artificial light
scantily only, or not at all, there can be no doubt that the
moonlight nights are for him a very important addition to the time
of daylight. And as a small proportion only of the whole number
of nights are without some portion of moonlight, the fact that
sometimes both luminaries are invisible very little diminishes the
value of this advantage. Why we have not more moonlight, either in
duration or in quantity, is an inquiry which a philosopher could
hardly be tempted to enter upon, by any success which has attended
previous speculations of a similar nature. Why should not the moon
be ten times as large as she is? Why should not the pupil of man’s
eye be ten times as large as it is, so as to receive more of the
light which does arrive? We do not conceive that our inability
to answer the latter question prevents our knowing that the eye
was made for seeing: nor does our inability to answer the former,
disturb our persuasion that the moon was made to give light upon
the earth.
Laplace suggests that if the moon had been placed at a certain
distance beyond the earth, it would have revolved about the sun in
the same time as the earth does, and would have always presented
to us a full moon. For this purpose it must have been about four
times as far from us as it really is; and would therefore, other
things remaining unchanged, have only been _one sixteenth_ as
large to the eye as our present full moon. We shall not dwell on
the discussion of this suggestion, for the reason just intimated.
But we may observe that in such a system as Laplace proposes,
it is not yet proved, we believe, that the arrangement would be
stable under the influence of the disturbing forces. And we may add
that such an arrangement, in which the motion of one body has a
_co-ordinate_ reference to two others, as the motion of the moon on
this hypothesis would have to the sun and the earth, neither motion
being subordinate to the other, is contrary to the whole known
analogy of cosmical phenomena, and therefore has no claim to our
notice as a subject of discussion.
2. In turning our consideration to the satellites of the other
planets of our system, there is one fact which immediately arrests
our attention;--the number of such attendant bodies appears to
increase as we proceed to planets farther and farther from the
sun. Such at least is the general rule. Mercury and Venus, the
planets nearest the sun, have no such attendants: the Earth has
one. Mars, indeed, who is still farther removed, has none; nor
have the minor planets, Juno, Vesta, Ceres, Pallas; so that the
rule is only approximately verified. But Jupiter, who is at five
times the earth’s distance, has four satellites; and Saturn, who
is again at a distance nearly twice as great, has seven, besides
that most extraordinary phenomenon his ring, which, for purposes of
illumination, is equivalent to many thousand satellites. Of Uranus
it is difficult to speak, for his great distance renders it almost
impossible to observe the smaller circumstances of his condition.
It does not appear at all probable that he has a ring, like Saturn;
but he has at least five satellites which are visible to us, at the
enormous distance of nine hundred millions of miles; and we believe
that the astronomer will hardly deny that he may possibly have
thousands of smaller ones circulating about him.
But leaving conjecture, and taking only the ascertained cases
of Venus, the Earth, Jupiter, and Saturn, we conceive that a
person of common understanding will be strongly impressed with
the persuasion that the satellites are placed in the system
with a view to compensate for the diminished light of the sun
at greater distances. The smaller planets, Juno, Vesta, Ceres,
and Pallas, differ from the rest in so many ways, and suggest so
many conjectures of reasons for such differences, that we should
almost expect to find them exceptions to such a rule. Mars is a
more obvious exception. Some persons might conjecture from his
case, that the arrangement itself, like other useful arrangements,
has been brought about by some wider law which we have not yet
detected. But whether or not we entertain such a guess, (it can be
nothing more,) we see in other parts of creation, so many examples
of apparent exceptions to rules, which are afterwards found to be
explained, or provided for by particular contrivances, that no one,
familiar with such contemplations, will, by one anomaly, be driven
from the persuasion that the end which the arrangements of the
satellites seem suited to answer is really one of the ends of their
creation.
CHAPTER VI.
_The Stability of the Ocean._
What is meant by the stability of the ocean may perhaps be
explained by means of the following illustration. If we suppose
the whole globe of the Earth to be composed of water, a sphere
of cork, immersed in any part of it, would come to the surface
of the water, except it were placed exactly at the centre of the
earth; and even if it were the slightest displacement of the cork
sphere would end in its rising and floating. This would be the case
whatever were the size of the cork sphere, and even if it were so
large as to leave comparatively little room for the water; and the
result would be nearly the same, if the cork sphere, when in its
central position, had on its surface prominences which projected
above the surface of the water. Now this brings us to the case in
which we have a globe resembling our present earth, composed like
it of water and of a solid centre, with islands and continents,
but having these solid parts all made of cork. And it appears by
the preceding reasoning, that in this case, if there were any
disturbance either of the solid or fluid parts, the solid parts
would rise from the centre of the watery sphere as far as they
could: that is, all the water would run to one side and leave the
land on the other. Such an ocean would be in _unstable_ equilibrium.
Now a question naturally occurs, is the equilibrium of our present
ocean of this unstable kind, or is it stable? The sea, after its
most violent agitations, appears to return to its former state of
repose; but may not some extraordinary cause produce in it some
derangement which may go on increasing till the waters all rush one
way, and thus drown the highest mountains? And if we are safe from
this danger, what are the conditions by which we are so secured?
The illustration which we have employed obviously suggests the
answer to this question; namely, that the equilibrium is unstable,
so long as the solid parts are of such a kind as to float in the
fluid parts; and of course we should expect that the equilibrium
will be stable whenever the contrary is the case, that is, when
the solid parts of the earth are of greater specific gravity than
the sea. A more systematic mathematical calculation has conducted
Laplace to a demonstration of this result.
The mean specific gravity of the earth appears to be about _five_
times that of water, so that the condition of the stability of the
ocean is abundantly fulfilled. And the provision by which this
stability is secured was put in force through the action of those
causes, whatever they were, which made the density of the solid
materials and central parts of the earth greater than the density
of the incumbent fluid.
When we consider, however, the manner in which the wisdom of the
Creator, even in those cases in which his care is most apparent,
as in the structure of animals, works by means of intermediate
causes and general laws, we shall not be ready to reject all belief
of an end in such a case as this, merely because the means are
mechanical agencies. Laplace says, “in virtue of gravity, the most
dense of the strata of the earth are those nearest to the centre;
and thus the mean density exceeds that of the waters which cover
it; which suffices to secure the stability of the equilibrium of
the seas, and to put a bridle upon the fury of the waves.” This
statement, if exact, would not prove that He who subjected the
materials of the earth to the action of gravity did not _intend_
to restrain the rage of the waters: but the statement is not true
in fact. The lower strata, so far as man has yet examined, are
very far from being constantly, or even generally, heavier than
the superincumbent ones. And certainly solidification by no means
implies a greater density than fluidity: the density of Jupiter
is one fourth, that of Saturn less than one seventh, of that of
the earth. If an ocean of water were poured into the cavities upon
the surface of Saturn, its equilibrium would _not_ be stable. It
would leave its bed on one side of the globe; and the planet would
finally be composed of one hemisphere of water and one of land.
If the Earth had an ocean of a fluid six times as heavy as water,
(quicksilver is thirteen times as heavy,) we should have, in like
manner, a dry and a fluid hemisphere. Our inland rivers would
probably never be able to reach the shores, but would be dried up
on their way, like those which run in torrid desarts; perhaps the
evaporation from the ocean would never reach the inland mountains,
and we should have no rivers at all. Without attempting to imagine
the details of such a condition, it is easy to see, that to secure
the existence of a different one is an end which is in harmony with
all that we see of the preserving care displayed in the rest of
creation.[20]
CHAPTER VII.
_The Nebular Hypothesis._
We have referred to Laplace, as a profound mathematician, who has
strongly expressed the opinion, that the arrangement by which
the stability of the solar system is secured is not the result
of chance; that “_a primitive cause_ has directed the planetary
motions.” This author, however, having arrived, as we have done,
at this conviction, does not draw from it the conclusion which has
appeared to us so irresistible, that “the admirable arrangement
of the solar system cannot but be the work of an intelligent and
most powerful being.” He quotes these expressions, which are
those of Newton, and points at them as instances where that great
philosopher had deviated from the method of true philosophy.
He himself proposes an hypothesis concerning the nature of the
_primitive cause_ of which he conceives the existence to be thus
probable: and this hypothesis, on account of the facts which it
attempts to combine, the view of the universe which it presents,
and the eminence of the person by whom it is propounded, deserves
our notice.
1. Laplace conjectures that in the original condition of the solar
system, the sun revolved upon his axis, surrounded by an atmosphere
which, in virtue of an excessive heat, extended far beyond the
orbits of all the planets, the planets as yet having no existence.
The heat gradually diminished, and as the solar atmosphere
contracted by cooling, the rapidity of its rotation increased by
the laws of rotatory motion, and an exterior zone of vapour was
detached from the rest, the central attraction being no longer able
to overcome the increased centrifugal force. This zone of vapour
might in some cases retain its form, as we see it in Saturn’s
ring; but more usually the ring of vapour would break into several
masses, and these would generally coalesce into one mass, which
would revolve about the sun. Such portions of the solar atmosphere,
abandoned successively at different distances, would form “planets
in the state of vapour.” These planets, it appears from mechanical
considerations, would have each its rotatory motion, and as the
cooling of the vapour still went on, would each produce a planet,
which might have satellites and rings, formed from the planet in
the same manner as the planets were formed from the atmosphere of
the sun.
It may easily be conceived that all the primary motions of a system
so produced would be nearly circular, nearly in the plane of the
original equator of the solar rotation, and in the direction of
that rotation. Reasons are offered also to show that the motions
of the satellites thus produced and the motions of rotation of the
planets must be in the same direction. And thus it is held that the
hypothesis accounts for the most remarkable circumstances in the
structure of the solar system: namely, the motions of the planets
in the same direction, and almost in the same plane; the motions
of the satellites in the same direction as those of the planets;
the motions of rotation of these different bodies still in the same
direction as the other motions, and in planes not much different;
the small eccentricity of the orbits of the planets, upon which
condition, along with some of the preceding ones, the stability of
the system depends; and the position of the source of light and
heat in the centre of the system.
It is not necessary for the purpose, nor suitable to the plan
of the present treatise, to examine, on physical grounds, the
probability of the above hypothesis. It is proposed by its author,
with great diffidence, as a conjecture only. We might, therefore,
very reasonably put off all discussion of the bearings of this
opinion upon our views of the government of the world, till the
opinion itself should have assumed a less indistinct and precarious
form. It can be no charge against our doctrines, that there is
a difficulty in reconciling with them arbitrary guesses and
half-formed theories. We shall, however, make a few observations
upon this _nebular hypothesis_, as it may be termed.
2. If we grant, for a moment, the hypothesis, it by no means proves
that the solar system was formed without the intervention of
intelligence and design. It only transfers our view of the skill
exercised, and the means employed, to another part of the work.
For, how came the sun and its atmosphere to have such materials,
such motions, such a constitution, that these consequences
followed from their primordial condition? How came the parent
vapour thus to be capable of coherence, separation, contraction,
solidification? How came the laws of its motion, attraction,
repulsion, condensation, to be so fixed, as to lead to a beautiful
and harmonious system in the end? How came it to be neither too
fluid nor too tenacious, to contract neither too quickly nor too
slowly, for the successive formation of the several planetary
bodies? How came that substance, which at one time was a luminous
vapour, to be at a subsequent period, solids and fluids of many
various kinds? What but design and intelligence prepared and
tempered this previously existing element, so that it should by its
natural changes produce such an orderly system?
And if in this way we suppose a planet to be produced, what sort
of a body would it be?--something, it may be presumed, resembling
a large meteoric stone. How comes this mass to be covered with
motion and organization, with life and happiness? What primitive
cause stocked it with plants and animals, and produced all the
wonderful and subtle contrivances which we find in their structure,
all the wide and profound mutual dependencies which we trace in
their economy? Was man, with his thought and feeling, his powers
and hopes, his will and conscience, also produced as an ultimate
result of the condensation of the solar atmosphere? Except we allow
a prior purpose and intelligence presiding over this material
“primitive cause,” how irreconcilable is it with the evidence which
crowds in upon us from every side!
3. In the next place, we may observe concerning this hypothesis,
that it carries us back to the beginning of the present system
of things; but that it is impossible for our reason to stop at
the point thus presented to it. The sun, the earth, the planets,
the moons were brought into their present order out of a previous
state, and, as is supposed in the theory, by the natural operation
of laws. But how came that previous state to exist? We are
compelled to suppose that it, in like manner, was educed from a
still prior state of things; and this, again, must have been the
result of a condition prior still. Nor is it possible for us to
find, in the tenets of the nebular hypothesis, any resting place or
satisfaction for the mind. The same reasoning faculty, which seeks
for the origin of the present system of things, and is capable
of assenting to, or dissenting from the hypothesis propounded
by Laplace as an answer to this inquiry, is necessarily led to
seek, in the same manner, for the origin of any previous system
of things, out of which the present may appear to have grown: and
must pursue this train of inquiries unremittingly, so long as the
answer which it receives describes a mere assemblage of matter and
motion; since it would be to contradict the laws of matter and the
nature of motion, to suppose such an assemblage to be the _first_
condition.
The reflection just stated, may be illustrated by the further
consideration of the Nebular Hypothesis. This opinion refers us,
for the origin of the solar system, to a sun surrounded with an
atmosphere of enormously elevated temperature, revolving and
cooling. But as we ascend to a still earlier period, what state
of things are we to suppose?--a still higher temperature, a still
more diffused atmosphere. Laplace conceives that, in its primitive
state, the sun consisted in a diffused luminosity so as to resemble
those nebulæ among the fixed stars, which are seen by the aid of
the telescope, and which exhibit a nucleus, more or less brilliant,
surrounded by a cloudy brightness. “This anterior state was itself
preceded by other states, in which the nebulous matter was more and
more diffuse, the nucleus being less and less luminous. We arrive,”
Laplace says, “in this manner, at a nebulosity so diffuse, that its
existence could scarcely be suspected.”
“Such is,” he adds, “in fact, the first state of the nebulæ which
Herschel carefully observed by means of his powerful telescopes.
He traced the progress of condensation, not indeed on one nebula,
for this progress can only become perceptible to us in the course
of centuries; but in the assemblage of nebulæ; much in the same
manner as in a large forest we may trace the growth of trees among
the examples of different ages which stand side by side. He saw in
the first place the nebulous matter dispersed in patches, in the
different parts of the sky. He saw in some of these patches this
matter feebly condensed round one or more faint nuclei. In other
nebulæ, these nuclei were brighter in proportion to the surrounding
nebulosity; when by a further condensation the atmosphere of each
nucleus becomes separate from the others, the result is multiple
nebulous stars, formed by brilliant nuclei very near each other,
and each surrounded by an atmosphere: sometimes the nebulous matter
condensing in a uniform manner has produced nebulous systems
which are called _planetary_. Finally, a still greater degree of
condensation transforms all these nebulous systems into stars. The
nebulæ, classed according to this philosophical view, indicate with
extreme probability their future transformation into stars, and
the anterior nebulous condition of the stars which now exist.”
It appears then that the highest point to which this series of
conjectures can conduct us, is, “an extremely diffused nebulosity,”
attended, we may suppose, by a far higher degree of heat, than that
which, at a later period of the hypothetical process, keeps all the
materials of our earth and planets in a state of vapour. Now is it
not impossible to avoid asking, whence was this light, this heat,
this diffusion? How came the laws which such a state implies, to be
already in existence? Whether light and heat produce their effects
by means of fluid vehicles or otherwise, they have complex and
varied laws which indicate the existence of some subtle machinery
for their action. When and how was this machinery constructed?
Whence too that enormous expansive power which the nebulous matter
is supposed to possess? And if, as would seem to be supposed in
this doctrine, all the material ingredients of the earth existed
in this diffuse nebulosity, either in the state of vapour, or in
some state of still greater expansion, whence were they and their
properties? how came there to be of each simple substance which
now enters into the composition of the universe, just so much and
no more? Do we not, far more than ever, require an origin of this
origin? an explanation of this explanation? Whatever may be the
merits of the opinion as a physical hypothesis, with which we do
not here meddle, can it for a moment prevent our looking beyond
the hypothesis, to a First Cause, an Intelligent Author, an origin
proceeding from free volition, not from material necessity?
But again: let us ascend to the highest point of the hypothetical
progression: let us suppose the nebulosity diffused throughout
all space, so that its course of running into patches is not yet
begun. How are we to suppose it distributed? Is it equably diffused
in every part? clearly not; for if it were, what should cause it
to gather into masses, so various in size, form and arrangement?
The separation of the nebulous matter into distinct nebulæ implies
necessarily some original inequality of distribution; some
determining circumstances in its primitive condition. Whence were
these circumstances? this inequality? we are still compelled to
seek some ulterior agency and power.
Why must the primeval condition be one of change at all? Why should
not the nebulous matter be equably diffused throughout space, and
continue for ever in its state of equable diffusion, as it must
do, from the absence of all cause to determine the time and manner
of its separation? why should this nebulous matter grow cooler and
cooler? why should it not retain for ever the same degree of heat,
whatever heat be? If heat be a fluid, if to cool be to part with
this fluid, as many philosophers suppose, what becomes of the fluid
heat of the nebulous matter, as the matter cools down? Into what
unoccupied region does it find its way?
Innumerable questions of the same kind might be asked, and the
conclusion to be drawn is, that every new physical theory which
we include in our view of the universe, involves us in new
difficulties and perplexities, if we try to erect it into an
ultimate and final account of the existence and arrangement of
the world in which we live. With the evidence of such theories,
considered as scientific generalizations of ascertained facts,
with their claims to a place in our natural philosophy, we have
here nothing to do. But if they are put forwards as a disclosure
of the ultimate cause of that which occurs, and as superseding
the necessity of looking further or higher; if they claim a place
in our Natural Theology, as well as our Natural Philosophy;
we conceive that their pretensions will not bear a moment’s
examination.
Leaving then to other persons and to future ages to decide upon the
scientific merits of the nebular hypothesis, we conceive that the
final fate of this opinion cannot, in sound reason, affect at all
the view which we have been endeavouring to illustrate;--the view
of the universe as the work of a wise and good Creator. Let it be
supposed that the point to which this hypothesis leads us, is the
ultimate point of physical science: that the farthest glimpse we
can obtain of the material universe by our natural faculties, shows
it to us occupied by a boundless abyss of luminous matter: still we
ask, how space came to be thus occupied, how matter came to be thus
luminous? If we establish by physical proofs, that the first fact
which can be traced in the history of the world, is that “there
was light;” we shall still be led, even by our natural reason,
to suppose that before this could occur, “God said, let there be
light.”
CHAPTER VIII.
_The Existence of a Resisting Medium in the Solar System._
The question of a _plenum_ and a _vacuum_ was formerly much
debated among those who speculated concerning the constitution of
the universe; that is, they disputed whether the celestial and
terrestrial spaces are absolutely full, each portion being occupied
by some matter or other; or whether there are, between and among
the material parts of the world, empty spaces free from all matter,
however rare. This question was often treated by means of abstract
conceptions and _à priori_ reasonings; and was sometimes considered
as one in which the result of the struggle between rival systems of
philosophy, the Cartesian and Newtonian for instance, was involved.
It was conceived by some that the Newtonian doctrine of the motions
of the heavenly bodies, according to mechanical laws, required
that the space in which they moved should be, absolutely and
metaphysically speaking, a vacuum.
This, however, is not necessary to the truth of the Newtonian
doctrines, and does not appear to have been intended to be asserted
by Newton himself. Undoubtedly, according to his theory, the
motions of the heavenly bodies were calculated _on the supposition_
that they do move in a space void of any resisting fluid; and the
comparison of the places so calculated with the places actually
observed, (continued for a long course of years, and tried in
innumerable cases,) did not show any difference which implied the
existence of a resisting fluid. The Newtonian, therefore, was
justified in asserting that _either_ there was no such fluid, _or_
that it was so thin and rarefied, that no phenomenon yet examined
by astronomers was capable of betraying its effects.
This was all that the Newtonian needed or ought to maintain; for
his philosophy, founded altogether upon observation, had nothing to
do with abstract possibilities and metaphysical necessities. And in
the same manner in which observation and calculation thus showed
that there could be none but a very rare medium pervading the solar
system, it was left open to observation and calculation to prove
that there was such a medium, if any facts could be discovered
which offered suitable evidence.
Within the last few years, facts have been observed which show,
in the opinion of some of the best mathematicians of Europe, that
such a very rare medium does really occupy the spaces in which the
planets move; and it may be proper and interesting to consider the
bearing of this opinion upon the views and arguments which we have
had here to present.
1. Reasons might be offered, founded on the universal diffusion of
light and on other grounds, for believing that the planetary spaces
cannot be entirely free from matter of some kind; and wherever
matter is, we should expect resistance. But the facts which have
thus led astronomers to the conviction that such a resisting
medium really exists, are certain circumstances occurring in the
motion of a body revolving round the sun, which is now usually
called _Encke’s comet_. This body revolves in a very eccentric
or oblong orbit, its greatest or aphelion distance from the sun,
and its nearest, or perihelion distance, being in the proportion
of more than ten to one. In this respect it agrees with other
comets; but its time of revolution about the sun is much less
than that of the comets which have excited most notice; for while
they appear only at long intervals of years, the body of which we
are now speaking returns to its perihelion every twelve hundred
and eight days, or in about three years and one-third. Another
observable circumstance in this singular body, is its extreme
apparent tenuity: it appears as a loose indefinitely formed speck
of vapour, through which the stars are visible with no perceptible
diminution of their brightness. This body was first seen by
Mechain and Messier, in 1786,[21] but they obtained only two
observations, whereas three, at least, are requisite to determine
the path of a heavenly body. Miss Herschel discovered it again in
1795, and it was observed by several European astronomers. In 1805
it was again seen, and again in 1819. Hitherto it was supposed
that the four comets thus observed were all different; Encke,
however, showed that the observations could only be explained by
considering them as returns of the same revolving body; and by
doing this, well merited that his name should be associated with
the subject of his discovery. The return of this body in 1822,
was calculated beforehand, and observed in New South Wales, the
comet being then in the southern part of the heavens; but on
comparing the calculated and the observed places, Encke concluded
that the observations could not be exactly explained, without
supposing a resisting medium. This comet was again generally
observed in Europe in 1825 and 1828, and the circumstances of the
last appearance were particularly favourable for determining the
absolute amount of the retardation arising from the medium, which
the other observations had left undetermined.
The effect of this retarding influence is, as might be supposed
from what has already been said, extremely slight; and would
probably not have been perceptible at all, but for the loose
texture and small quantity of matter of the revolving body. It will
easily be conceived that a body which has perhaps no more solidity
or coherence than a cloud of dust, or a wreath of smoke, will have
less force to make its way through a fluid medium, however thin,
than a more dense and compact body would have. In atmospheric air
much rarefied, a bullet might proceed for miles without losing any
of its velocity, while such a loose mass as the comet is supposed
to be would lose its projectile motion in the space of a few
yards. This consideration will account for the circumstance, that
the existence of such a medium has been detected by observing the
motions of Encke’s comet, though the motions of the heavenly bodies
previously observed showed no trace of such an impediment.
It will appear perhaps remarkable that a body so light and loose as
we have described this comet to be, should revolve about the sun by
laws as fixed and certain as those which regulate the motions of
those great and solid masses, the Earth and Jupiter. It is however
certain from observation, that this comet is acted upon by exactly
the same force of solar attraction, as the other bodies of the
system; and not only so, but that it also experiences the same kind
of disturbing force from the action of the other planets, which
they exercise upon each other. The effect of all these causes has
been calculated with great care and labour; and the result has been
an agreement with observation sufficiently close to show that these
causes really act, but at the same time a _residual phenomenon_
(as Sir J. Herschel expresses it) has come to light: and from this
has been collected the inference of a resisting medium.
This medium produces a very small effect upon the motion of the
comet, as will easily be supposed from what has been said. By
Encke’s calculation, it appears that the effect of the resistance,
supposing the comet to move in the earth’s orbit, would be about
an eight hundred and fiftieth of the sun’s force on the body. The
effect of such resistance may appear, at first sight, paradoxical;
it would be to make the comet _move_ more slowly, but _perform
its revolutions_ more quickly. This, however, will perhaps be
understood if it be considered that by _moving_ more slowly the
comet will be more rapidly _drawn_ towards the centre, and that in
this way a revolution will be described by a shorter path than it
was before. It appears that in getting round the sun, the comet
gains more in this way than it loses by the diminution of its
velocity. The case is much like that of a stone thrown in the air;
the stone moves more slowly than it would do if there were no air;
but yet it comes to the earth _sooner_ than it would do on that
supposition.
It appears that the effect of the resistance of the ethereal
medium, from the first discovery of the comet up to the present
time, has been to diminish the time of revolution by about two
days: and the comet is ten days in advance of the place which it
would have reached, if there had been no resistance.
2. The same medium which is thus shown to produce an effect upon
Encke’s comet, must also act upon the planets which move through
the same spaces. The effect upon the planets, however, must be very
much smaller than the effect upon the comet, in consequence of
their greater quantity of matter.
It is not easy to assign any probable value, or even any certain
limit, to the effect of the resisting medium upon the planets.
We are entirely ignorant of the comparative mass of the comet,
and of any of the planets; and hence, cannot make any calculation
founded on such a comparison. Newton has endeavoured to show how
small the resistance of the medium must be, if it exist.[22] The
result of his calculation is, that if we take the density of the
medium to be that which our air will have at two hundred miles from
the earth’s surface, supposing the law of diminution of density
to go on unaltered, and if we suppose Jupiter to move in such a
medium, he would in a million years lose less than a millionth
part of his velocity. If a planet, revolving about the sun, were
to lose any portion of its velocity by the effect of resistance,
it would be drawn proportionally nearer the sun, the tendency
towards the centre being no longer sufficiently counteracted by
that centrifugal force which arises from the body’s velocity. And
if the resistance were to continue to act, the body would be drawn
perpetually nearer and nearer to the centre, and would describe its
revolutions quicker and quicker, till at last it would reach the
central body, and the system would cease to be a system.
This result is true, however small be the velocity lost by
resistance; the only difference being, that when the resistance
is small, the time requisite to extinguish the whole motion will
be proportionally longer. In all cases the times which come under
our consideration in problems of this kind, are enormous to common
apprehension. Thus Encke’s comet, according to the results of
the observations already made, will lose, in ten revolutions, or
thirty-three years, less than one thousandth of its velocity:
and if this law were to continue, the velocity would not be
reduced to one-half its present value in less than seven thousand
revolutions or twenty-three thousand years. If Jupiter were to
lose one-millionth of his velocity in a million years, (which,
as has been seen, is far more than can be considered in any way
probable,) he would require seventy millions of years to lose
one-thousandth of the velocity; and a period seven hundred times as
long to reduce the velocity to one-half. These are periods of time
which quite overwhelm the imagination; and it is not pretended that
the calculations are made with any pretensions to accuracy. But
at the same time it is beyond doubt that though the intervals of
time thus assigned to these changes are highly vague and uncertain,
the changes themselves must, sooner or later, take place, in
consequence of the existence of the resisting medium. Since there
is such a retarding force perpetually acting, however slight it
be, it must in the end destroy all the celestial motions. It may
be millions of millions of years before the earth’s retardation
may perceptibly affect the apparent motion of the sun; but still
the day will come (if the same Providence which formed the system,
should permit it to continue so long) when this cause will entirely
change the length of our year and the course of our seasons, and
finally stop the earth’s motion round the sun altogether. The
smallness of the resistance, however small we choose to suppose it,
does not allow us to escape this certainty. There is a resisting
medium; and, therefore, the movements of the solar system cannot go
on for ever. The moment such a fluid is ascertained to exist, the
eternity of the movements of the planets becomes as impossible as a
perpetual motion on the earth.
3. The vast periods which are brought under our consideration
in tracing the effects of the resisting medium, harmonize with
all that we learn of the constitution of the universe from
other sources. Millions, and millions of millions of years are
expressions that at first sight appear fitted only to overwhelm and
confound all our powers of thought; and such numbers are no doubt
beyond the limits of any thing which we distinctly conceive. But
our powers of conception are suited rather to the wants and uses
of common life, than to a complete survey of the universe. It is in
no way unlikely that the whole duration of the solar system should
be a period immeasurably great in our eyes, though demonstrably
finite. Such enormous numbers have been brought under our notice
by all the advances we have made in our knowledge of nature. The
smallness of the objects detected by the microscope and of their
parts;--the multitude of the stars which the best telescopes of
modern times have discovered in the sky;--the duration assigned
to the globe of the earth by geological investigation;--all these
results require for their probable expression, numbers, which so
far as we see, are on the same gigantic scale as the number of
years in which the solar system will become entirely deranged.
Such calculations depend in some degree on our relation to the
vast aggregate of the works of our Creator; and no person who is
accustomed to meditate on these subjects will be surprised that
the numbers which such an occasion requires should oppress our
comprehension. No one who has dwelt on the thought of a universal
Creator and Preserver, will be surprised to find the conviction
forced upon the mind by every new train of speculation, that viewed
in reference to Him, our space is a point, our time a moment, our
millions a handful, our permanence a quick decay.
Our knowledge of the vast periods, both geological and
astronomical, of which we have spoken, is most slight. It is in
fact little more than that such periods exist; that the surface of
the earth has, at wide intervals of time, undergone great changes
in the disposition of land and water, and in the forms of animal
life; and that the motions of the heavenly bodies round the sun
are affected, though with inconceivable slowness, by a force which
must end by deranging them altogether. It would therefore be rash
to endeavour to establish any analogy between the periods thus
disclosed; but we may observe that they _agree_ in this, that
they reduce all things to the general rule of _finite duration_.
As all the geological states of which we find evidence in the
present state of the earth, have had their termination, so also the
astronomical conditions under which the revolutions of the earth
itself proceed, involve the necessity of a future cessation of
these revolutions.
The contemplative person may well be struck by this universal law
of the creation. We are in the habit sometimes of contrasting the
transient destiny of man with the permanence of the forests, the
mountains, the ocean,--with the unwearied circuit of the sun. But
this contrast is a delusion of our own imagination; the difference
is after all but one of degree. The forest tree endures for its
centuries and then decays; the mountains crumble and change, and
perhaps subside in some convulsion of nature; the sea retires,
and the shore ceases to resound with the “everlasting” voice of
the ocean: such reflections have already crowded upon the mind of
the geologist; and it now appears that the courses of the heavens
themselves are not exempt from the universal law of decay; that not
only the rocks and the mountains, but the sun and the moon have
the sentence “to end” stamped upon their foreheads. They enjoy
no privilege beyond man except a longer respite. The ephemeron
perishes in an hour; man endures for his three score years and ten;
an empire, a nation, numbers its centuries, it may be its thousands
of years; the continents and islands which its dominion includes
have perhaps their date, as those which preceded them have had; and
the very revolutions of the sky by which centuries are numbered
will at last languish and stand still.
To dwell on the moral and religious reflections suggested by
this train of thought is not to our present purpose; but we may
observe that it introduces a _homogeneity_, so to speak, into
the government of the universe. Perpetual change, perpetual
progression, increase and diminution, appear to be the rules of
the material world, and to prevail without exception. The smaller
portions of matter which we have near us, and the larger, which
appear as luminaries at a vast distance, different as they are
in our mode of conceiving them, obey the same laws of motion;
and these laws produce the same results; in both cases motion is
perpetually destroyed, except it be repaired by some living power;
in both cases the relative rest of the parts of a material system
is the conclusion to which its motion tends.
4. It may perhaps appear to some, that this acknowledgment of
the tendency of the system to derangement through the action of
a resisting medium is inconsistent with the argument which we
have drawn in a previous chapter, from the provisions for its
stability. In reality, however, the two views are in perfect
agreement, so far as our purpose is concerned. The main point
which we had to urge, in the consideration of the stability of
the system, was, not that it is constructed to last for ever,
but that while it lasts, the deviations from its mean condition
are very small. It is this property which fits the world for
its uses. To maintain either the past or the future eternity of
the world, does not appear consistent with physical principles,
as it certainly does not fall in with the convictions of the
religious man, in whatever way obtained. We conceive that this
state of things has had a beginning; we conceive that it will have
an end. But in the mean time we find it fitted, by a number of
remarkable arrangements, to be the habitation of living creatures.
The conditions which secure the stability, and the smallness of
the perturbations of the system, are among these provisions. If
the eccentricity of the orbit of Venus, or of Jupiter, were much
greater than it is, not only might some of the planets, at the
close of ages, fall into the sun or fly off into infinite space,
but also, in the intermediate time, the earth’s orbit might become
much more eccentric; the course of the seasons and the average of
temperature might vary from what they now are, so as to injure
or destroy the whole organic creation. By certain original
arrangements these destructive oscillations are prevented. So long
as the bodies continue to revolve, their orbits will not be much
different from what they now are. And this result is not affected
by the action of the resisting medium. Such a medium cannot
increase the small eccentricities of the orbits. The range of the
periodical oscillations of heat and cold will not be extended by
the mechanical effect of the medium, nor would be, even if its
density were incomparably greater than it is. The resisting medium
therefore does not at all counteract that which is most important
in the provision for the permanency of the solar system. If the
stability of the system had not been secured by the adjustments
which we described in a former chapter, the course of the seasons
might have been disturbed to an injurious or even destructive
extent in the course of a few centuries, or even within the limits
of one generation; by the effect of the resisting medium, the order
of nature remains unchanged for a period, compared with which the
known duration of the human race is insignificant.
But, it may be objected, the effect of the medium must be
ultimately to affect, the duration of the earth’s revolution round
the sun, and thus to derange those adaptations which depend on the
length of the year. And, without question, if we permit ourselves
to look forward to that inconceivably distant period at which the
effect of the medium will become sensible, this must be allowed
to be true, as has been already stated. Millions, and probably
millions of millions, of years express inadequately the distance of
time at which this cause would produce a serious effect. That the
machine of the universe is so constructed that it may answer its
purposes for such a period, is surely sufficient proof of the skill
of its workmanship, and of the reality of its purpose: and those
persons, probably, who are best convinced that it is the work of
a wise and good Creator, will be least disposed to consider the
system as imperfect, because in its present condition it is not
fitted for eternity.
5. The doctrine of a Resisting Medium leads us towards a point
which the Nebular Hypothesis assumes;--a _beginning_ of the present
order of things. There must have been a commencement of the motions
now going on in the solar system. Since these motions, when once
begun, would be deranged and destroyed in a period which, however
large, is yet finite, it is obvious we cannot carry their origin
indefinitely backwards in a range of past duration. There is a
period in which these revolutions, whenever they had begun, would
have brought the revolving bodies into contact with the central
mass; and this period has in our system not yet elapsed. The watch
is still going, and therefore it must have been wound up within a
limited time.
The solar system, at this its beginning, must have been arranged
and put in motion by some cause. If we suppose this cause to
operate by means of the configurations and the properties of
previously existing matter, these configurations must have resulted
from some still previous cause, these properties must have produced
some previous effects. We are thus led to a condition still earlier
than the assumed beginning;--to an origin of the original state of
the universe; and in this manner we are carried perpetually further
and further back, through a labyrinth of mechanical causation,
without any possibility of finding any thing in which the mind
can acquiesce or rest, till we admit “a First Cause which is not
mechanical.”
Thus the argument which was before urged against those in
particular, who put forwards the Nebular Hypothesis in opposition
to the admission of an Intelligent Creator, offers itself again, as
cogent in itself, when we adopt the opinion of a resisting medium,
for which the physical proofs have been found to be so strong.
The argument is indeed forced upon our minds, whatever view we
take of the past history of the universe. Some have endeavoured
to evade its force by maintaining that the world as it now exists
has existed from eternity. They assert that the present order of
things, or an order of things in some way resembling the present,
produced by the same causes, governed by the same laws, has
prevailed through an infinite succession of past ages. We shall
not dwell upon any objections to this tenet which might be drawn
from our own conceptions, or from what may be called metaphysical
sources. Nor shall we refer to the various considerations which
history, geology, and astronomical records supply, and which tend
to show, not only that the past duration of the present course of
things is finite, but that it is short, compared with such periods
as we have had to speak of. But we may observe, that the doctrine
of a resisting medium once established, makes this imagination
untenable; compels us to go back to the origin, not only of the
present course of the world, not only of the earth, but of the
solar system itself; and thus sets us forth upon that path of
research into the series of past causation, where we obtain no
answer of which the meaning corresponds to our questions, till
we rest in the conclusion of a most provident and most powerful
Creating Intelligence.
It is related of Epicurus that when a boy, reading with his
preceptor these verses of Hesiod,
Ητοι μεν πρωτιζα Χαος γενετ’, αυταρ επειτα
Γαι’ ευρυζερνος παντων εδος ασφαλες αιει
Αθανατων,
Eldest of beings, Chaos first arose,
Thence Earth wide stretched, the steadfast seat of all
The Immortals,
the young scholar first betrayed his inquisitive genius by asking
“And chaos whence?” When in his riper years he had persuaded
himself that this question was sufficiently answered by saying that
chaos arose from the concourse of atoms, it is strange that the
same inquisitive spirit did not again suggest the question “and
atoms whence?” And it is clear that however often the question
“whence?” had been answered, it would still start up as at first.
Nor could it suffice as an answer to say, that earth, chaos, atoms,
were portions of a series of changes which went back to eternity.
The preceptor of Epicurus informed him, that to be satisfied on the
subject of his inquiry, he must have recourse to the philosophers.
If the young speculator had been told that chaos (if chaos indeed
preceded the present order) was produced by an Eternal Being, in
whom resided purpose and will, he would have received a suggestion
which, duly matured by subsequent contemplation, might have led
him to a philosophy far more satisfactory than the material scheme
can ever be, to one who looks, either abroad into the universe, or
within into his own bosom.
CHAPTER IX.
_Mechanical Laws._
In the preceding observations we have supposed the laws, by which
different kinds of matter act and are acted upon, to be already in
existence; and have endeavoured to point out evidences of design
and adaptation, displayed in the selection and arrangement of these
materials of the universe. These materials are, it has appeared,
supplied in such measures and disposed in such forms, that by means
of their properties and laws the business of the world goes on
harmoniously and beneficially. But a further question occurs: how
came matter to have such properties and laws? Are these also to
be considered as things of selection and institution? And if so,
can we trace the reasons why the laws were established in their
present form; why the properties which matter actually possesses
were established and bestowed and bestowed upon it? We have already
attempted, in a previous part of this work, to point out some of
the advantages which are secured by the existing laws of heat,
light and moisture. Can we, in the same manner, point out the
benefits which arise from the present constitution of those laws
of matter which are mainly concerned in the production of cosmical
phenomena?
It will readily be perceived that the discussion of this point
must necessarily require some effort of abstract thought. The laws
and properties of which we have here to speak, the laws of motion
and the universal properties of matter, are so closely interwoven
with our conceptions of the external world, that we have great
difficulty in conceiving them not to exist, or to exist other than
they are. When we press or lift a stone, we can hardly imagine that
it could, by possibility, do otherwise than resist our effort by
its hardness and by its heaviness, qualities so familiar to us:
when we throw it, it seems inevitable that its motion should depend
on the impulse we give, just as we find that it invariably does.
Nor is it easy to say how far it is really possible to suppose
the fundamental attributes of matter to be different from what
they are. If we, in our thoughts, attempt to divest matter of its
powers of resisting and moving, it ceases to be matter, according
to our conceptions, and we can no longer reason upon it with any
distinctness. And yet it is certain that we can conceive the laws
of hardness and weight and motion to be quite different from what
they are, and can point out some of the consequences which would
result from such difference. The properties of matter, even the
most fundamental and universal ones, do not obtain by any absolute
necessity, resembling that which belongs to the properties of
geometry. A line touching a circle is _necessarily_ perpendicular
to a line drawn to the centre through the point touched; for
it may be shown that the contrary involves a contradiction. But
there is no contradiction in supposing that a body’s motion should
naturally diminish, or that its weight should increase in removing
further from the earth’s centre.
Thus the properties of matter and the laws of motion are what we
find them, not by virtue of any internal necessity which we can
understand. The study of such laws and properties may therefore
disclose to us the character of that external agency by which
we conceive them to have been determined to be what they are;
and this must be the same agency by which all other parts of the
constitution of the universe were appointed and ordered.
But we can hardly expect, with regard to such subjects, that
we shall be able to obtain any complete or adequate view of
the reasons why these general laws are so selected, and so
established. These laws are the universal basis of all operations
which go on, at any moment, in every part of space, with regard
to every particle of matter, organic and inorganic. All other
laws and properties must have a reference to these, and must be
influenced by them; both such as men have already discovered, and
the far greater number which remain still unknown. The general
economy and mutual relations of all parts of the universe, must
be subordinate to the laws of motion and matter of which we
here speak. We can easily suppose that the various processes of
nature, and the dependencies of various creatures, are affected
in the most comprehensive manner by these laws;--are simplified
by _their_ simplicity, made consistent by _their_ universality;
rendered regular by _their_ symmetry. We can easily suppose that
in this way there may be the most profound and admirable reasons
for the existence of the present universal properties of matter,
which we cannot apprehend in consequence of the limited nature
of our knowledge, and of our faculties. For, compared with the
whole extent of the universe, the whole aggregate of things and
relations and connexions which exist in it, our knowledge is
most narrow and partial, most shallow and superficial. We cannot
suppose, therefore, that the reasons which we discover for the
present form of the laws of nature go nearly to the full extent, or
to the bottom of the reasons, which a more complete and profound
insight would enable us to perceive. To do justice to such reasons,
would require nothing less than a perfect acquaintance with the
whole constitution of every part of creation; a knowledge which man
has not, and, so far as we can conceive, never can have.
We are certain, therefore, that our views, with regard to this
part of our subject, must be imperfect and limited. Yet still man
has _some_ knowledge with regard to various portions of nature;
and with regard to those most general and comparatively simple
facts to which we now refer, his knowledge is more comprehensive,
and goes deeper than it does in any other province. We conceive,
therefore, that we shall not be engaged in any rash or presumptuous
attempt, if we endeavour to point out some of the advantages which
are secured by the present constitution of some of the general
mechanical laws of nature; and to suggest the persuasion of that
purpose and wise design, which the selection of such laws will thus
appear to imply.
CHAPTER X.
_The Law of Gravitation._
We shall proceed to make a few observations on the Law of Gravity,
in virtue of which the motions of planets about the sun, and of
satellites about their planets take place; and by which also are
produced the fall downwards of all bodies within our reach, and
the pressure which they exert upon their supports when at rest.
The identification of the latter forces with the former, and the
discovery of the single law by which these forces are every where
regulated, was the great discovery of Newton: and we wish to make
it appear that this law is established by an intelligent and
comprehensive selection.
The law of the sun’s attraction upon the planets is, that this
attraction varies _inversely_ as the square of the distance; that
is, it decreases as that square increases. If we take three points
or planets of the solar system, the distances of which from the
sun are in proper proportion one, two, three; the attractive force
which the sun at these distances exercises, is as one, one-fourth,
and one-ninth respectively. In the smaller variations of distance
which occur in the elliptical motion of one planet, the variations
of the force follow the same law. Moreover, not only does the
sun attract the planets, but they attract each other according
to the same law; the tendency to the earth which makes bodies
heavy, is one of the effects of this law: and all these effects of
the attractions of large masses may be traced to the attractions
of the particles of which they are composed; so that the final
generalization, including all the derivative laws, is, that every
particle of matter in the universe attracts every other, according
to the law of the inverse square of the distance.
Such is the law of universal gravitation. Now, the question
is, why do either the attractions of masses, or those of their
component particles, follow this law of the inverse square of the
distance rather than any other? When the distance becomes one,
two, and three, why should not the force also become one, two, and
three?--or if it must be weaker at points more remote from the
attracting body, why should it not be one, a half, a third? or one,
an eighth, a twenty-seventh? Such law’s could easily be expressed
mathematically, and their consequences calculated. Can any reason
be assigned why the law which we find in operation _must_ obtain?
Can any be assigned why it _should_ obtain?
The answer to this is, that no reason, at all satisfactory, can be
given why such a law must, of necessity, be what it is; but that
very strong reasons can be pointed out why, for the beauty and
advantage of the system, the present one is better than others. We
will point out some of these reasons.
1. In the first place, the system could not have subsisted, if
the force had followed a _direct_ instead of an inverse law, with
respect to the distance; that is, if it had increased when the
distance increased. It has been sometimes said, that “all direct
laws of force are excluded on account of the danger from perturbing
forces;”[23] that if the planets had pulled at this earth, the
harder the further off they were, they would have dragged it
entirely out of its course. This is not an exact statement of
what would happen: if the force were to be simply in the direct
ratio of the distance, any number of planets might revolve in the
most regular and orderly manner. Their mutual effects, which we
may call perturbations if we please, would be considerable; but
these perturbations would be so combined with the unperturbed
motion, as to produce a new motion not less regular than the
other. This curious result would follow, that every body in the
system would describe, or seem to describe, about every other,
an exact elliptical orbit; and that the times of the revolution
of every body in its orbit would be all equal. This is proved by
Newton, in the sixty-fourth proposition of the Principia. There
would be nothing to prevent all the planets, on this supposition,
from moving round the sun in orbits exactly circular, or nearly
circular, according to the mode in which they were set in motion.
But though the perturbations of the system would not make this
law inadmissible, there are other circumstances which would do so.
Under this law, the gravity of bodies at the earth’s surface would
cease to exist. Nothing would fall or weigh downwards. The greater
action of the distant sun and planets would exactly neutralize the
gravity of the earth: a ball thrown from the hand, however gently,
would immediately become a satellite of the earth, and would for
the future accompany it in its course, revolving about it in the
space of one year. All terrestrial things would float about with no
principle of coherence or stability: they would obey the general
law of the system, but would acknowledge no particular relation
to the earth. We can hardly pretend to judge of the abstract
possibility of such a system of things; but it is clear that it
could not exist without an utter subversion of all that we can
conceive of the economy and structure of the world which we inhabit.
With any other direct law of force, we should in like manner
lose gravity, without gaining the theoretical regularity of
the planetary motions which we have described in the case just
considered.
2. Among _inverse_ laws of the distance, (that is, those according
to which the force diminishes as the distance from the origin of
force increases,) all which diminish the central force faster than
the _cube_ of the distance increases are inadmissible, because they
are incompatible with the permanent revolution of a planet. Under
such laws it would follow, that a planet would describe a spiral
line about the sun, and would either approach nearer and nearer to
him perpetually, or perpetually go further and further off: nearly
as a stone at the end of a string, when the string is whirled
round, and is allowed to wrap round the hand, or to unwrap from it,
approaches to or recedes from the hand.
If we endeavour to compare the law of the inverse square of
the distance, which really regulates the central force, with
other laws, not obviously inadmissible, as for instance, the
inverse simple ratio of the distance, a considerable quantity
of calculation is found to be necessary in order to trace the
results, and especially the perturbations in the two cases. The
perturbations in the supposed case have not been calculated;
such a calculation being a process so long and laborious that it
is never gone through, except for the purpose of comparing the
results of theory with those of observation, as we can do with
regard to the law of inverse square. We can only say, therefore,
that the stability of the system, and the moderate limits of the
perturbations, which we know to be secured by the existing law,
would not, so far as we know, be obtained by any different law.
Without going into further examination of the subject, we may
observe that there are some circumstances in which the present
system has a manifest superiority in its simplicity over the
condition which would have belonged to it if the force had followed
any other law. Thus, with the present law of gravitation the
planets revolve, returning perpetually on the same track, very
nearly. The earth describes an oval, in consequence of which motion
she is nearer to the sun in our winter than in our summer by about
one-thirtieth part of the whole distance. And, as the matter now
is, the nearest approach to the sun, and the farthest recess
from him, occur always at the same points of the orbit. There is
indeed a slight alteration in these points arising from disturbing
forces, but this is hardly sensible in the course of several ages.
Now if the force had followed any other law, we should have had
the earth running perpetually on a new track. The greatest and
least distances would have occurred at different parts in every
successive revolution. The orbit would have perpetually intersected
and been interlaced with the path described in former revolutions;
and the simplicity and regularity which characterizes the present
motion would have been quite wanting.
3. Another peculiar point of simplicity in the present law of
mutual attraction is this: that it makes the law of attraction for
spherical masses the same as for single particles. If particles
attract with forces which are inversely as the square of the
distance, spheres composed of such particles, will exert a force
which follows the same law. In this character the present law
is singular, among all possible laws, excepting that of the
direct distance which we have already discussed. If the law of
the gravitation of particles had been that of the inverse simple
distance, the attraction of a sphere would have been expressed by
a complex series of mathematical expressions, each representing
a simple law. It is truly remarkable that the law of the inverse
square of the distance, which appears to be selected as that of
the _masses_ of the system, and of which the mechanism is, that it
arises from the action of the _particles_ of the system, should
lead us to the same law for the action of these particles: there is
a striking _prerogative_ of simplicity in the law thus adopted.
The law of gravitation actually prevailing in the solar system has
thus great and clear advantages over any law widely different from
it; and has moreover, in many of its consequences, a simplicity
which belongs to this precise law alone. It is in many such
respects a _unique_ law; and when we consider that it possesses
several _properties_ which are _peculiar_ to it, and several
_advantages_ which may be peculiar to it, and which are certainly
nearly so; we have some ground, it would appear, to look upon its
peculiarities and its advantages as connected. For the reasons
mentioned in the last chapter, we can hardly expect to see fully
the way in which the system is benefited by the simplicity of this
law, and by the mathematical elegance of its consequences: but when
we see that it has some such beauties, and some manifest benefits,
we may easily suppose that our ignorance and limited capacity alone
prevent our seeing that there are, for the selection of this law of
force, reasons of a far more refined and comprehensive kind than
we can distinctly apprehend.
4. But before quitting this subject we may offer a few further
observations on the question, whether gravitation and the law of
gravitation be _necessary_ attributes of matter. We have spoken of
the selection of this law, but is it selected? Could it have been
otherwise? Is not the force of attraction a necessary consequence
of the fundamental properties of matter?
This is a question which has been much agitated among the followers
of Newton. Some have maintained, as Cotes, that gravity is an
inherent property of all matter; others, with Newton himself, have
considered it as an appendage to the essential qualities of matter,
and have proposed hypotheses to account for the mode in which its
effects are produced.
The result of all that can be said on the subject appears to be
this: that no one can demonstrate the possibility of deducing
gravity from the acknowledged fundamental properties of matter: and
that no philosopher asserts, that matter has been found to exist,
which was destitute of gravity. It is a property which we have no
right to call _necessary_ to matter, but every reason to suppose
_universal_.
If we could show gravity to be a necessary consequence of those
properties which we adopt as essential to our notion of matter,
(extension, solidity, mobility, inertia) we might then call it also
one of the essential properties. But no one probably will assert
that this is the case. Its universality is a fact of observation
merely. How then can a property,--in its existence so needful for
the support of the universe, in its laws so well adapted to the
purposes of creation,--how came it to be thus universal? Its being
found every where is necessary for its uses; but this is so far
from being a sufficient explanation of its existence, that it is
an additional fact to be explained. We have here, then, an agency
most simple in its rule, most comprehensive in its influence, most
effectual and admirable in its operation. What evidence could be
afforded of design, by laws of mechanical action, which this law
thus existing and thus operating does not afford us?
5. It is not necessary for our purpose to consider the theories
which have been proposed to account for the action of gravity. They
have proceeded on the plan of reducing this action to the result of
pressure or impulse. Even if such theories could be established,
they could not much, or at all, affect our argument; for the
arrangements by which pressure or impact could produce the effects
which gravity produces, must be at least as clearly results of
contrivance, as gravity itself can be.
In fact, however, none of these attempts can be considered as at
all successful. That of Newton is very remarkable: it is found
among the Queries in the second edition of his Optics. “To show,”
he says, “that I do not take gravity for an essential property of
bodies, I have added one question concerning its cause, choosing to
propose it by way of question, because I am not yet satisfied about
it for want of experiments.” The hypothesis which he thus suggests
is, that there is an elastic medium pervading all space, and
increasing in elasticity as we proceed from dense bodies outwards:
that this “causes the gravity of such dense bodies to each other:
every body endeavouring to go from the denser parts of the medium
towards the rarer.” Of this hypothesis we may venture to say, that
it is in the first place quite gratuitous; we cannot trace in any
other phenomena a medium possessing these properties: and in the
next place, that the hypothesis contains several suppositions which
are more complex than the fact to be explained, and none which
are less so. Can we, on Newton’s principles, conceive an elastic
medium otherwise than as a collection of particles, repelling each
other? and is the repulsion of such particles a simpler fact than
the attraction of those which gravitate? And when we suppose that
the medium becomes more elastic as we proceed from each attracting
body, what cause can we conceive capable of keeping it in such a
condition, except a repulsive force emanating from the body itself:
a supposition at least as much requiring to be accounted for, as
the attraction of the body. It does not appear, then, that this
hypothesis will bear examination; although, for our purpose, the
argument would be rather strengthened than weakened, if it could be
established.
6. Another theory of the cause of gravity, which at one time
excited considerable notice, was that originally proposed by M.
Le Sage, in a memoir entitled “Lucrece Newtonien,” and further
illustrated by M. Prevost; according to which all space is occupied
by currents of matter, moving perpetually in straight lines, in
all directions, with a vast velocity, and penetrating all bodies.
When two bodies are near each other, they intercept the current
which would flow in the intermediate space if they were not there,
and thus receive a tendency towards each other from the pressure
of the currents on their farther sides. Without examining further
this curious and ingenious hypothesis, we may make upon it the same
kind of observations as before;--that it is perfectly gratuitous,
except as a means of explaining the phenomena; and that, if it were
proved, it would still remain to be shown what necessity has caused
the existence of these _two kinds_ of matter; the first kind being
that which is commonly called matter, and which alone affects our
senses, while it is inert as to any tendency to motion; the second
kind being something imperceptible to our senses, except by the
effects it produces on matter of the former kind; yet exerting an
impulse on every material body, permeating every portion of common
matter, flowing with inconceivable velocity, in inexhaustible
abundance, from every part of the abyss of infinity on one side,
to the opposite part of the same abyss; and so constituted that
through all eternity it can never bend its path, or return, or
tarry in its course.
If we were to accept this theory, it would little or nothing
diminish our wonder at the structure of the universe. We might well
continue to admire the evidence of contrivance, if such a machinery
should be found to produce all the effects which flow from the law
of gravitation.
7. The arguments for and against the necessity of the law of
the inverse square of the distance in the force of gravity,
were discussed with great animation about the middle of the
last century. Clairault, an eminent mathematician, who did
more than almost any other person for the establishment and
development of the Newtonian doctrines, maintained, at one period
of his researches, not only that the inverse square was not the
_necessary_ law, but also that it was not the _true_ law. The
occasion of this controversy was somewhat curious.
Newton and other astronomers had found that the line of the moon’s
_apsides_ (that is of her greatest and least distances from the
earth) moves round to different parts of the heavens with a
velocity twice as great as that which the calculation from the law
of gravitation seems at first to give. According to the theory,
it appeared that this line ought to move round once in eighteen
years; according to observation, it moves round once in nine
years. This difference, the only obvious failure of the theory of
gravitation, embarrassed mathematicians exceedingly. It is true,
it was afterwards discovered that the apparent discrepancy arose
from a mistake; the calculation, which is long and laborious, was
supposed to have been carried far enough to get close to the truth;
but it appeared afterwards that the residue which had been left out
as insignificant, produced, by an unexpected turn in the reckoning,
an effect as large as that which had been taken for the whole. But
this discovery was not made till afterwards; and in the mean time
the law of the inverse square appeared to be at fault. Clairault
tried to remedy the defect by supposing that the force of the
earth’s gravity consisted of a large force varying as the square of
the distance, and a very small force varying as the fourth power
(the square of the square.) By such a supposition, observation and
theory could be reconciled; but on the suggestion of it, Buffon
came forward with the assertion that the force _could_ not vary
according to any other law than the inverse square. His arguments
are rather metaphysical than physical or mathematical. Gravity,
he urges, is a quality, an emanation; and all emanations are
inversely as the square of the distance, as light, odours. To this
Clairault replies by asking, how we know that light and odours
have their intensity inversely as the square of the distance from
their origin: not, he observes, by measuring the intensity, but
by _supposing_ these effects to be material emanations. But who,
he asks, supposes gravity to be a material emanation _from_ the
attracting body.
Buffon again pleads that so many facts prove the law of the inverse
square, that a single one, which occurs to interfere with this
agreement, must be in some manner capable of being explained away.
Clairault replies, that the facts do _not_ prove this law to obtain
exactly; that small effects, of the same order as the one under
discussion, have been neglected; and that therefore the law is only
known to be true, _as far_ as such an approximation goes, and no
farther.
Buffon then argues, that there can be no such additional fraction
of the force, following a different law, as Clairault supposes: for
what, he asks, is there to determine the magnitude of the fraction
to one amount rather than another? why should nature select for it
any particular magnitude? To this it is replied, that, whether we
can explain the fact or not, nature does select certain magnitudes
in preference to others: that where we ascertain she does this,
we are not to deny the fact because we cannot assign the grounds
of her preference. What is there, it is asked, to determine the
magnitude of the whole force at any fixed distance? We cannot tell;
yet the force is of a certain definite intensity and no other.
Finally, Clairault observes, that we have, in cohesion, capillary
attraction, and various other cases, examples of forces varying
according to other laws than the inverse square; and that therefore
this cannot be the only possible law.
The discrepancy between observation and theory which gave rise to
this controversy was removed, as has been already stated, by a more
exact calculation: and thus, as Laplace observes, in this case
the metaphysician turned out to be right and the mathematician to
be wrong. But most persons, probably, who are familiar with such
trains of speculation, will allow, that Clairault had the best of
the argument, and that the attempts to show the law of gravitation
to be necessarily what it is, are fallacious and unsound.
8. We may observe, however, that the law of gravitation according
to the inverse square of the distance, which thus regulates the
motions of the solar system, is not confined to that province of
the universe, as has been shown by recent researches. It appears
by the observations and calculations of Sir John Herschel, that
several of the stars, called _double stars_, consist of a pair of
luminous bodies which revolve above each other in ellipses, in such
a manner as to show that the force, by which they are attracted
to each other, varies according to the law of the inverse square.
We thus learn a remarkable fact concerning bodies which seemed so
far removed that no effort of our science could reach them; and we
find that the same law of mutual attraction which we have before
traced to the farthest bounds of the solar system, prevails also
in spaces at a distance compared with which the orbit of Saturn
shrinks into a point. The establishment of such a truth certainly
suggests, as highly probable, the prevalence of this law among
all the bodies of the universe. And we may therefore suppose, that
the same ordinance which gave to the parts of our system that rule
by which they fulfil the purposes of their creation, impressed
the same rule on the other portions of matter which are scattered
in the most remote parts of the universe; and thus gave to their
movements the same grounds of simplicity and harmony which we find
reason to admire, as far as we can acquire any knowledge of our own
more immediate neighbourhood.
CHAPTER XI.
_The Laws of Motion._
We shall now make a few remarks on the general Laws of Motion by
which all mechanical effects take place. Are we to consider these
as instituted laws? and if so, can we point out any of the reasons
which we may suppose to have led to the selection of those laws
which really exist?
The observations formerly made concerning the inevitable narrowness
and imperfection of our conclusions on such subjects, apply here,
even more strongly than in the case of the law of gravitation. We
can hardly conceive matter divested of these laws; and we cannot
perceive or trace a millionth part of the effects which they
produce. We cannot, therefore, expect to go far in pointing out the
advantages of these laws such as they now obtain.
It would be easy to show that the fundamental laws of motion, in
whatever form we state them, possess a very preeminent simplicity,
compared with almost all others, which we might imagine as
existing. This simplicity has indeed produced an effect on men’s
minds which, though delusive, appears to be very natural; several
writers have treated these laws as self-evident, and necessarily
flowing from the nature of our conceptions. We conceive that this
is an erroneous view, and that these laws are known to us to be
what they are, by experience only; that they might, so far as we
can discern, have been any others. They appear therefore to be
selected for their fitness to answer their purposes; and we may,
perhaps, be able to point out some instances in which this fitness
is apparent to us.
Newton, and many English philosophers, teach the existence of
_three_ separate fundamental laws of motion, while most of the
eminent mathematicians of France reduce these to _two_, the law
of inertia and the law that force is proportioned to velocity. As
an example of the views which we wish to illustrate, we may take
the law of inertia, which is identical with Newton’s first Law of
Motion. This law asserts, that a body at rest continues at rest,
and that a body in motion goes on moving with its velocity and
direction unchanged, except so far as it is acted on by extraneous
forces.[24]
We conceive that this law, simple and universal as it is, cannot
be shown to be necessarily true. It might be difficult to discuss
this point in general terms with any clearness; but let us take
the only example which we know of a motion absolutely uniform, in
consequence of the absence of any force to accelerate or retard
it;--this motion is the rotation of the earth on its axis.
1. It is scarcely possible that discussions on such subjects
should not have a repulsive and scholastic aspect, and appear like
disputes about words rather than things. For mechanical writers
have exercised all their ingenuity so to circumscribe their notions
and so to define their terms that these fundamental truths should
be expressed in the simplest manner: the consequence of which has
been, that they have been made to assume the appearance rather
of identical assertions than of general facts of experience. But
in order to avoid this inconvenience, as far as may be, let us
take the _first law of motion_ as exemplified in a particular
case, the rotation of the earth. Of all the motions with which
we are acquainted this is alone invariable. Each day, measured
by the passages of the stars, is so precisely of the same length
that, according to Laplace’s calculations, it is impossible
that a difference of hundredth of a second of time should have
obtained between the length of the day in the earliest ages and
at the present time. Now why is this? How is this very remarkable
uniformity preserved in this particular phenomenon, while all the
other motions of the system are subject to inequalities? How is it
that in the celestial machine no retardation takes place by the
lapse of time, as would be the case in any machine which it would
be possible for human powers to construct? The answer is, that in
the earth’s revolution on her axis no cause operates to retard
the speed, like the imperfection of materials, the friction of
supports, the resistance of the ambient medium; impediments which
cannot, in any human mechanism, however perfect, be completely
annihilated. But here we are led to ask again, why should the
speed continue the same when not affected by an extraneous cause?
Why should it not languish and decay of itself by the mere lapse
of time? That it might do so, involves no contradiction, for
it was the common, though erroneous, belief of all mechanical
speculators, to the time of Galileo. We can conceive velocity to
diminish in proceeding from a certain point of time, as easily as
we can conceive force to diminish in proceeding from a certain
point of space, which in attractive forces really occurs. But,
it is sometimes said, the _motion_ (that is the velocity) _must_
continue the same from one instant to another, for there is nothing
to change it. This appears to be taking refuge in words. We may
call the velocity, that is the speed of a body, its motion; but
we cannot, by giving it this name, make it a _thing_ which has
any _à priori_ claim to permanence, much less any self-evident
constancy. Why must the speed of a body, left to itself, continue
the same, any more than its temperature? Hot bodies grow cooler of
themselves, why should not quick bodies go slower of themselves?
Why must a body describe one thousand feet in the next second
because it has described one thousand feet in the last? Nothing
but experience, under proper circumstances, can inform us whether
bodies, abstracting from external agency, do move according to
such a rule. We find that they do so, we learn that all diminution
of their speed which ever takes place, can be traced to external
causes. Contrary to all that men had guessed, motion appears to
be of itself endless and unwearied. In order to account for the
unalterable permanence of the length of our day, all that is
requisite is to show that there is no let or hindrance in the way
of the earth’s rotation;--no resisting medium or alteration of
size,--she “spinning _sleeps_” on her axle, as the poet expresses
it, and may go on sleeping with the same regularity for ever, so
far as the experimental properties of motion are concerned.
Such is the necessary consequence of the first law of motion;
but the law itself has no necessary existence, so far as we can
see. It was discovered only after various perplexities and false
conjectures of speculators on mechanics. We have learnt that it is
so, but we have not learnt, nor can any one undertake to teach us,
that it must have been so. For aught we can tell, it is one among
a thousand equally possible laws, which might have regulated the
motions of bodies.
2. But though we have thus no reason to consider this as the only
possible law, we have good reason to consider it as the best, or at
least as possessing all that we can conceive of advantage. It is
the _simplest_ conceivable of such laws. If the velocity had been
compelled to change with the time, there must have been a law of
the change, and the kind and amount of this change must have been
determined by its dependence on the time and other conditions.
This, though quite supposable, would undoubtedly have been more
complex than the present state of things. And though complexity
does not appear to embarrass the operations of the laws of nature,
and is admitted, without scruple, when there is reason for it,
simplicity is the usual character of such laws, and appears to have
been a ground of selection in the formation of the universe, as it
is a mark of beauty to us in our contemplation of it.
But there is a still stronger apparent reason for the selection
of this law of the preservation of motion. If the case had been
otherwise, the universe must necessarily in the course of ages
have been reduced to a state of rest, or at least to a state not
sensibly differing from it. If the earth’s motion, round its
axis, had slackened by a very small quantity, for instance, by
a hundredth of a second in a revolution, and in this proportion
continued, the day would have been already lengthened by six hours
in the six thousand years which have elapsed since the history
of the world began; and if we suppose a longer period to precede
or to follow, the day might be increased to a month or to any
length. All the adaptations which depend on the length of the day
would consequently be deranged. But this would not be all; for
the same law of motion is equally requisite for the preservation
of the annual motion of the earth. If her motion were retarded by
the establishment of any other law instead of the existing one,
she would wheel nearer and nearer to the sun at every revolution,
and at last reach the centre, like a falling hoop. The same would
happen to the other planets; and the whole solar system would,
in the course of a certain period, be gathered into a heap of
matter without life or motion. In the present state of things on
the other hand, the system, as we have already explained, is, by
a combination of remarkable provisions, calculated for an almost
indefinite existence, of undiminished fitness for its purposes.
There are, therefore, manifest reasons, why, of all laws which
could occupy the place of the first law of motion, the one which
now obtains is the only one consistent with the durability and
uniformity of the system;--the one, therefore, which we may
naturally conceive to be selected by a wise contriver. And as,
along with this, it has appeared that we have no sort of right to
attribute the establishment of this law to any thing but selection,
we have here a striking evidence, to lead us to a perception of
that Divine mind, by which means so simple are made to answer
purposes so extensive and so beneficial.
CHAPTER XII.
_Friction._[25]
We shall not pursue this argument of the last chapter, by
considering the other laws of motion in the same manner as we have
there considered the first, which might be done. But the facts
which form exceptions and apparent contradictions to the first law
of which we have been treating, and which are very numerous, offer,
we conceive, an additional exemplification of the same argument;
and this we shall endeavour to illustrate.
The rule that a body naturally moves for ever with an undiminished
speed, is so far from being obviously true, that it appears on a
first examination to be manifestly false. The hoop of the school
boy, left to itself, runs on a short distance, and then stops; his
top spins a little while, but finally flags and falls; all motion
on the earth appears to decay by its own nature; all matter which
we move appears to have a perpetual tendency to divest itself of
the velocity which we communicate to it. How is this reconcileable
with the first law of motion on which we have been insisting?
It is reconciled principally by considering the effect of
_Friction_. Among terrestrial objects friction exerts an agency
almost as universal and constant as the laws of motion themselves;
an agency which completely changes and disguises the results of
those laws. We shall consider some of these effects.
It is probably not necessary to explain at any length the nature
and operation of friction. When a body cannot move without causing
two surfaces to rub together, this rubbing has a tendency to
diminish the body’s motion or to prevent it entirely. If the
body of a carriage be placed on the earth without the wheels, a
considerable force will be requisite in order to move it at all:
it is here the friction against the ground which obstructs the
motion. If the carriage be placed on its wheels, a much less force
will move it, but if moved it will soon stop: it is the friction at
the ground and at the axles which stops it: placed on a level rail
road, with well made and well oiled wheels, and once put in motion,
it might run a considerable distance alone, for the friction is
here much less; but there is friction, and therefore the motion
would after a time cease.
1. The friction which we shall principally consider is the friction
which _prevents_ motion. So employed, friction is one of the most
universal and important agents in the mechanism of our daily
comforts and occupations. It is a force which is called into play
to an extent incomparably greater than all the other forces with
which we are concerned in the course of our daily life. We are
dependent upon it at every instant and in every action; and it is
not possible to enumerate the ways in which it serves us; scarcely
even to suggest a sufficient number of them to give us a true
notion of its functions.
What can appear a more simple operation than standing and walking?
yet it is easy to see that without the aid of friction these simple
actions would scarcely be possible. Every one knows how difficult
and dangerous they are when performed on smooth ice. In such a
situation we cannot always succeed in standing: if the ice be very
smooth, it is by no means easy to walk, even when the surface is
perfectly level; and if it were ever so little inclined, no one
would make the attempt. Yet walking on the ice and on the ground
differ only in our experiencing more friction in the latter case.
We say _more_, for there is a considerable friction even in the
case of ice, as we see by the small distance which a stone slides
when thrown along the surface. It is this friction of the earth
which, at every step we take, prevents the foot from sliding back;
and thus allows us to push the body and the other foot forwards.
And when we come to violent bodily motions, to running, leaping,
pulling or pushing objects, it is easily seen how entirely we
depend upon the friction of the ground for our strength and force.
Every one knows how completely powerless we become in any of these
actions by the _foot slipping_.
In the same manner it is the friction of objects to which the
hand is applied, which enables us to hold them with any degree
of firmness. In some contests it was formerly the custom for the
combatants to rub their bodies with oil, that the adversary might
not be able to keep his grasp. If the pole of the boatman, the rope
of the sailor, were thus smooth and lubricated, how weak would be
the thrust and the pull! Yet this would only be the removal of
friction.
Our buildings are no less dependent on this force for their
stability. Some edifices are erected without the aid of cement; and
if the stones be large and well squared, such structures may be
highly substantial and durable; even when rude and slight, houses
so built answer the purposes of life. These are entirely upheld
by friction, and without that agent they would be thrown down by
the Zephyr, far more easily than if all the stones were lumps of
ice with a thawing surface. But even in cases where cement _binds_
the masonry, it does not take the duty of _holding_ it together.
In consequence of the existence of friction, there is no constant
tendency of the stones to separate; they are in a state of repose.
If this were not so, if every shock and every breeze required to be
counteracted by the cement, no composition exists which would long
sustain such a wear and tear. The cement excludes the corroding
elements, and helps to resist extraordinary violence; but it is
friction which gives the habitual state of rest.
We are not to consider friction as a _small_ force, slightly
modifying the effects of other agencies. On the contrary its
amount is in most cases very great. When a body lies loose on the
ground, the friction is equal to one-third or one-half, or in some
cases the whole of its weight. But in cases of bodies supported by
oblique pressure, the amount is far more enormous. In the arch of a
bridge, the friction which is called into play between two of the
vaulting stones, may be equal to the whole weight of the bridge.
In such cases this conservative force is so great, that the common
theory, which neglects it, does not help us even to guess what
will take place. According to the theory, certain forms of arches
only will stand, but in practice almost any form will stand, and it
is not easy to construct a model of a bridge which will fall.
We may see the great force of friction in the _brake_, by which
a large weight running down a long inclined plane has its motion
moderated and stopt; in the windlass, where a few coils of the
rope round a cylinder sustain the stress and weight of a large
iron anchor; in the nail or screw which holds together large
beams; in the mode of raising large blocks of granite by an iron
rod driven into a hole in the stone. Probably no greater forces
are exercised in any processes in the arts than the force of
friction; and it is always employed to produce rest, stability,
moderate motion. Being always ready and never wearied, always at
hand and augmenting with the exigency, it regulates, controls,
subdues all motions;--counteracts all other agents;--and finally
gains the mastery over all other terrestrial agencies, however
violent, frequent, or long continued. The perpetual action of all
other terrestrial forces appears, on a large scale, only as so many
interruptions of the constant and stationary rule of friction.
The objects which every where surround us, the books or dishes
which stand on our tables, our tables and chairs themselves, the
loose clods and stones in the field, the heaviest masses produced
by nature or art, would be in a perpetual motion, quick or slow
according to the forces which acted on them, and to their size, if
it were not for the tranquillizing and steadying effects of the
agent we are considering. Without this, our apartments, if they
kept their shape, would exhibit to us articles of furniture, and of
all other kinds, sliding and creeping from side to side with every
push and every wind, like loose objects in a ship’s cabin, when she
is changing her course in a gale.
Here, then, we have a force, most extensive and incessant in its
operation, which is absolutely essential to the business of this
terrestrial world, according to any notion which we can form. The
more any one considers its effects, and the more he will find how
universally dependent he is upon it, in every action of his life;
resting or moving, dealing with objects of art or of nature, with
instruments of enjoyment or of action.
2. Now we have to observe concerning this agent, Friction, that
we have no ground for asserting it to be a necessary result of
other properties of matter, for instance, of their solidity and
coherency. Philosophers have not been able to deduce the laws of
friction from the other known properties of matter, nor even to
explain what we know experimentally of such laws, (which is not
much,) without introducing new hypotheses concerning the surfaces
of bodies, &c.--hypotheses which are not supplied us by any other
set of phenomena. So far as our knowledge goes, friction is a
separate property, and may be conceived to have been bestowed upon
matter for particular purposes. How well it answers the purpose
of fitting matter for the uses of the daily life of man, we have
already seen.
We may make suppositions as to the mode in which friction is
connected with the texture of bodies; but little can be gained for
philosophy, or for speculation of any kind, by such conjectures
respecting unknown connexions. If, on the other hand, we consider
this property of friction, and find that it prevails there, and
there only, where the general functions, analogies, and relations
of the universe require it, we shall probably receive a strong
impression that it was introduced into the system of the world _for
a purpose_.
3. It is very remarkable that this force, which is thus so
efficacious and discharges such important offices in all earthly
mechanism, disappears altogether when we turn to the mechanism
of the heavens. All motions on the earth soon stop;--a machine
which imitates the movements of the stars cannot go long without
winding up: but the stars themselves have gone on in their courses
for ages, with no diminution of their motions, and offer no
obvious prospect of any change. This is so palpable a fact, that
the first attempts of men to systematize their mechanical notions
were founded upon it. The ancients held that motions were to be
distinguished into _natural_ motions and _violent_,--the former
go on without diminution--the latter are soon extinguished;--the
motions of the stars are of the former kind;--those of a stone
thrown, and in short all terrestrial motions, of the latter. Modern
philosophers maintain that the laws of motion are the same for
celestial and terrestrial bodies;--that all motions are _natural_
according to the above description;--but that in terrestrial
motions, friction comes in and alters their character,--destroys
them so speedily that they appear to have existed only during an
effort. And that this is the case will not now be contested. Is
it not then somewhat remarkable that the same laws which produce
a state of permanent motion in the heavens, should, on the earth,
give rise to a condition in which rest is the rule and motion the
exception? The air, the waters, and the lighter portions of matter
are, no doubt, in a state of perpetual motion; over these friction
has no empire: yet even their motions are interrupted, alternate,
variable, and on the whole slight deviations from the condition of
equilibrium. But in the solid parts of the globe, rest predominates
incomparably over motion: and this, not only with regard to the
portions which cohere as parts of the same solid; for the whole
surface of the earth is covered with loose masses, which, if the
power of friction were abolished, would rush from their places and
begin one universal and interminable dance, which would make the
earth absolutely uninhabitable.
If, on the other hand, the dominion of friction were extended in
any considerable degree into the planetary spaces, there would
soon be an end of the system. If the planet had moved in a fluid,
as the Cartesians supposed, and if this fluid had been subject to
the rules of friction which prevail in terrestrial fluids, their
motions could not have been of long duration. The solar system must
soon have ceased to be a system of revolving bodies.
But friction is neither abolished on the earth, nor active in the
heavens. It operates where it is wanted, it is absent where it
would be prejudicial. And both these circumstances occasion, in
a remarkable manner, the steadiness of the course of nature. The
stable condition of the objects in man’s immediate neighbourhood,
and the unvarying motions of the luminaries of heaven, are alike
conducive to his well-being. This requires that he should be able
to depend upon a fixed order of place, a fixed course of time. It
requires, therefore, that terrestrial objects should be affected by
friction, and that celestial should not; as is the case, in fact.
What further evidence of benevolent design could this part of the
constitution of the universe supply?
4. There is another view which may be taken of the forces which
operate on the earth to produce permanency or change. Some parts
of the terrestrial system are under the dominion of powers which
act energetically to prevent all motion, as the crystalline forces
by which the parts of rocks are bound together; other parts are
influenced by powers which produce a perpetual movement and change
in the matter of which they consist; thus plants and animals
are in a constant state of internal movement, by the agency of
the vital forces. In the former case rigid immutability, in the
latter perpetual developement, are the tendencies of the agencies
employed. Now in the case of objects affected by friction, we
have a kind of intermediate condition, between the constantly
fixed and the constantly moveable. Such objects can and do move;
but they move but for a short time if left to the laws of nature.
When at rest, they can easily be put in motion, but still not
with unlimited ease; a certain finite effort, different in
different cases, is requisite for their purpose. Now this immediate
condition, this capacity of receiving readily and alternately the
states of rest and motion, is absolutely requisite for the nature
of man, for the exertion of will, of contrivance, of foresight, as
well as for the comfort of life and the conditions of our material
existence. If all objects were fixed and immoveable, as if frozen
into one mass; or if they were susceptible of such motions only
as are found in the parts of vegetables, we attempt in vain to
conceive what would come of the business of the world. But besides
the state of a particle which cannot be moved, and of a particle
which cannot be stopped, we have the state of a particle moveable
but not moved; or moved, but moved only while we choose: and this
state is that about which the powers, the thoughts, and the wants
of man are mainly conversant.
Thus the forces by which solidity and by which organic action
are produced, the laws of permanence and of developement, do not
bring about all that happens. Besides these, there is a mechanical
condition, that of a body exposed to friction, which is neither
one of absolute permanency nor one naturally progressive; but is
yet one absolutely necessary to make material objects capable of
being instruments and aids to man; and this is the condition of by
far the greater part of terrestrial things. The habitual course of
events with regard to motion and rest is not the same for familiar
moveable articles, as it is for the parts of the mineral, or of
the vegetable world, when left to themselves; such articles are in
a condition far better adapted than any of those other conditions
would be, to their place and purpose. Surely this shows us an
_adaptation_, an adjustment, of the constitution of the material
world to the nature of man. And as the organization of plants
cannot be conceived otherwise than as having their life and growth
for its object, so we cannot conceive that friction should be
one of the leading agencies in the world in which man is placed,
without supposing that it was intended to be of use when man should
walk and run, and build houses and ships, and bridges, and execute
innumerable other processes, all of which would be impossible,
admirably constituted as man is in other respects, if friction did
not exist. And believing, as we conceive we cannot but believe,
that the laws of motion and rest were thus given with reference
to their ends, we perceive in this instance, as in others, how
wide and profound this reference is, how simple in its means, how
fertile in its consequences, how effective in its details.
BOOK III.
RELIGIOUS VIEWS.
The contemplation of the material universe exhibits God to us as
the author of the laws of material nature; bringing before us a
wonderful spectacle, in the simplicity, the comprehensiveness,
the mutual adaptation of these laws, and in the vast variety of
harmonious and beneficial effects produced by their mutual bearing
and combined operation. But it is the consideration of the moral
world, of the results of our powers of thought and action, which
leads us to regard the Deity in that light in which our relation
to him becomes a matter of the highest interest and importance. We
perceive that man is capable of referring his actions to principles
of right and wrong; that both his faculties and his virtues may
be unfolded and advanced by the discipline which arises from the
circumstances of human society; that good men can be discriminated
from the bad, only by a course of trial, by struggles with
difficulty and temptation; that the best men feel deeply the need
of relying, in such conflicts, on the thought of a superintending
Spiritual power; that our views of justice, our capacity for
intellectual and moral advancement, and a crowd of hopes and
anticipations which rise in our bosoms unsought, and cling there
with inexhaustible tenacity, will not allow us to acquiesce in the
belief that this life is the end of our existence. We are thus led
to see that our relation the Superintender of our moral being, to
the Depositary of the supreme law of just and right, is a relation
of incalculable consequence. We find that we cannot be permitted
to be merely contemplators and speculators with regard to the
Governor of the moral world; we must obey His will; we must turn
our affections to Him; we must advance in His favour; or we offend
against the nature of our position in the scheme of which He is the
author and sustainer.
It is far from our purpose to represent natural religion, as of
itself sufficient for our support and guidance; or to underrate the
manner in which our views of the Lord of the universe have been,
much more, perhaps, than we are sometimes aware, illustrated and
confirmed by lights derived from revelation. We do not here speak
of the manner in which men have come to believe in God, as the
Governor of the moral world; but of the fact, that by the aid of
one or both of these two guides, Reason or Revelation, reflecting
persons in every age have been led to such a belief. And we
conceive it may be useful to point out some connexion between such
a belief of a just and holy Governor, and the conviction, which we
have already endeavoured to impress upon the reader, of a wise and
benevolent Creator of the physical world. This we shall endeavour
to do in the present book.
At the same time that men have thus learnt to look upon God as
their Governor and Judge, the source of their support and reward,
they have also been led, not only to ascribe to him power and
skill, knowledge and goodness, but also attribute to him these
qualities in a mode and degree excluding all limit:--to consider
him as almighty, all-wise, of infinite knowledge and inexhaustible
goodness; every where present and active, but incomprehensible by
our minds, both in the manner of his agency, and the degree of his
perfections. And this impression concerning the Deity appears to be
that which the mind receives from all objects of contemplation and
all modes of advance towards truth. To this conception it leaps
with alacrity and joy, and in this it acquiesces with tranquil
satisfaction and growing confidence; while any other view of the
nature of the Divine Power which formed and sustained the world,
is incoherent and untenable, exposed to insurmountable objections
and intolerable incongruities. We shall endeavour to show that the
modes of employment of the thoughts to which the well conducted
study of nature gives rise, do tend, in all their forms, to
produce or strengthen this impression on the mind; and that such
an impression, and no other, is consistent with the widest views
and most comprehensive aspects of nature and of philosophy, which
our Natural Philosophy opens to us. This will be the purpose of
the latter part of the present book. In the first place we shall
proceed with the object first mentioned, the connexion which may
be perceived between the evidences of creative power, and of moral
government, in the world.
CHAPTER I.
_The Creator of the Physical World is the Governor of the Moral
World._
With our views of the moral government of the world and the
religious interests of man, the study of material nature is not and
cannot be directly and closely connected. But it may be of some
service to trace in these two lines of reasoning, seemingly so
remote, a manifest convergence to the same point, a demonstrable
unity of result. It may be useful to show that we are thus led, not
to two rulers of the universe, but to one God;--to make it appear
that the Creator and Preserver of the world is also the Governor
and Judge of men;--that the Author of the Laws of Nature is also
the Author of the Law of Duty;--that He who regulates corporeal
things by properties of attraction and affinity and assimilating
power, is the same Being who regulates the actions and conditions
of men, by the influence of the feeling of responsibility, the
perception of right and wrong, the hope of happiness, the love of
good.
The conviction that the Divine attributes which we are taught by
the study of the material world, and those which we learn from
the contemplation of man as a responsible agent, belong to the
same Divine Being, will be forced upon us, if we consider the
manner in which all the parts of the universe, the corporeal and
intellectual, the animal and moral, are connected with each other.
In each of these provinces of creation we trace refined adaptations
and arrangements which lead us to the Creator and Director of so
skilful a system; but these provinces are so intermixed, these
different trains of contrivance so interwoven, that we cannot,
in our thoughts, separate the author of one part from the author
of another. The Creator of the Heavens and of the Earth, of the
inorganic and of the organic world, of animals and of man, of the
affections and the conscience, appears inevitably to be one and the
same God.
We will pursue this reflection a little more into detail.
1. The _Atmosphere_ is a mere mass of fluid floating on the
surface of the ball of the earth; it is one of the inert and
inorganic portions of the universe, and must be conceived to have
been formed by the same Power which formed the solid mass of the
earth and all other parts of the solar system. But how far is the
atmosphere from being inert in its effects on organic beings, and
unconnected with the world of life! By what wonderful adaptations
of its mechanical and chemical properties, and of the vital powers
of plants, to each other, are the developement and well-being
of plants and animals secured! The creator of the atmosphere
must have been also the creator of plants and animals: we cannot
for an instant believe the contrary. But the atmosphere is not
only subservient to the life of animals, and of man among the
rest; it is also the vehicle of voice; it answers the purpose of
intercourse; and, in the case of man, of rational intercourse.
We have seen how remarkably the air is fitted for this office;
the construction of the organs of articulation, by which they are
enabled to perform their part of the work, is, as is well known,
a most exquisite system of contrivances. But though living in an
atmosphere capable of transmitting articulate sound, and though
provided with organs fitted to articulate, man would never attain
to the use of language, if he were not also endowed with another
set of faculties. The powers of abstraction and generalization,
memory and reason, the tendencies which occasion the inflexions
and combinations of words, are all necessary to the formation and
use of language. Are not these parts of the same scheme of which
the bodily faculties by which we are able to speak are another
part? Has man his mental powers independently of the creator of
his bodily frame? To what purpose then, or by what cause was
the curious and complex machinery of the tongue, the glottis,
the larynx produced? These are useful for speech, and full of
contrivances which suggest such a use as the end for which those
organs were constructed. But speech appears to have been no less
contemplated in the intellectual structure of man. The processes
of which we have spoken, generalization, abstraction, reasoning,
have a close dependence on the use of speech. These faculties are
presupposed in the formation of language, but they are developed
and perfected by the use of language. The mind of man then, with
all its intellectual endowments, is the work of the same artist by
whose hands his bodily frame was fashioned; as his bodily faculties
again are evidently constructed by the maker of those elements on
which their action depends. The creator of the atmosphere and of
the material universe is the creator of the human mind, and the
author of those wonderful powers of thinking, judging, inferring,
discovering, by we are able to reason concerning the world in which
we are placed; and which aid us in lifting our thoughts to the
source of our being himself.
2. _Light_, or the means by which light is propagated, is another
of the inorganic elements which forms a portion of the mere
material world. The luminiferous ether, if we adopt that theory,
or the fluid light of the theory of emission, must indubitably
pervade the remotest regions of the universe, and must be supposed
to exist, as soon as we suppose the material parts of the universe
to be in existence. The origin of light then must be at least as
far removed from us as the origin of the solar system. Yet how
closely connected are the properties of light with the structure
of our own bodies! The mechanism of the organs of vision and the
mechanism of light are, as we have seen, most curiously adapted to
each other. We must suppose, then, that the same power and skill
produced one and the other of these two sets of contrivances, which
so remarkably _fit into_ each other. The creator of light is the
author of our visual powers. But how small a portion does mere
visual perception constitute of the advantages which we derive from
vision! We possess ulterior faculties and capacities by which sight
becomes a source of happiness and good to man. The sense of beauty,
the love of art, the pleasure arising from the contemplation of
nature, are all dependent on the eye; and we can hardly doubt that
these faculties were bestowed on man to further the best interests
of his being. The sense of beauty both animates and refines his
domestic tendencies; the love of art is a powerful instrument for
raising him above the mere cravings and satisfactions of his animal
nature; the expansion of mind which rises in us at the sight of the
starry sky, the cloud-capt mountain, the boundless ocean, seems
intended to direct our thoughts by an impressive though indefinite
feeling, to the Infinite Author of All. But if these faculties be
thus part of the scheme of man’s inner being, given him by a good
and wise creator, can we suppose that this creator was any other
than the creator also of those visual organs, without which the
faculties could have no operation and no existence? As clearly as
light and the eye are the work of the same author, so clearly also
do our capacities for the most exalted visual pleasures, and the
feelings flowing from them, proceed from the same Divine Hand.
3. The creator of the earth must be conceived to be the author also
of all those qualities in the soil, chemical and whatever else, by
which it supports vegetable life, under all the modifications of
natural and artificial condition. Among the attributes which the
earth thus possesses, there are some which seem to have an especial
reference to man in a state of society. Such are--the power of the
earth to increase its produce under the influence of cultivation,
and the necessary existence of property in land, in order that this
cultivation may be advantageously applied; the rise, under such
circumstances, of a _surplus_ produce, of a quantity of subsistence
exceeding the wants of the cultivators alone; and the consequent
possibility of inequalities of rank, and of all the arrangements
of civil society. These are all parts of the constitution of the
earth. But these would all remain mere idle possibilities, if the
nature of man had not a corresponding direction. If man had not a
social and economical tendency, a disposition to congregate and
co-operate, to distribute possessions and offices among the members
of the community, to make and obey and enforce laws, the earth
would in vain be ready to respond to the care of the husbandman.
Must we not then suppose that this attribute of the earth was
bestowed upon it by Him who gave to man those corresponding
attributes, through which the apparent niggardliness of the soil
is the source of general comfort and security, of polity and law?
Must we not suppose that He who created the soil also inspired man
with those social desires and feelings which produce cities and
states, laws and institutions, arts and civilization; and that thus
the apparently inert mass of earth is a part of the same scheme as
those faculties and powers with which man’s moral and intellectual
progress is most connected?
4. Again:--It will hardly be questioned that the author of the
material elements is also the author of the structure of animals,
which is adapted to and provided for by the constitution of the
elements in such innumerable ways. But the author of the bodily
structure of animals must also be the author of their instincts,
for without these the structure would not answer its purpose. And
these instincts frequently assume the character of affections
in a most remarkable manner. The love of offspring, of home, of
companions, are often displayed by animals, in a way that strikes
the most indifferent observer; and yet these affections will hardly
be denied to be a part of the same scheme as the instincts by which
the same animals seek food and the gratifications of sense. Who can
doubt that the anxious and devoted affection of the mother-bird
for her young after they are hatched, is a part of the same system
of Providence as the instinct by which she is impelled to sit
upon her eggs? and this, of the same by which her eggs are so
organized that incubation leads to the birth of the young animal?
Nor, again, can we imagine that while the structure and affections
of animals belong to one system of things, the affections of man,
in many respects so similar to those of animals, and connected
with the bodily frame in a manner so closely analogous, can belong
to a different scheme. Who, that reads the touching instances of
maternal affection, related so often of the women of all nations,
and of the females of all animals, can doubt that the principle
of action is the same in the two cases, though enlightened in one
of them by the rational faculty: And who can place in separate
provinces the supporting and protecting love of the father and
the mother? or consider as entirely distinct from these, and
belonging to another part of our nature, the other kinds of family
affection? or disjoin man’s love of his home, his clan, his tribe,
his country, from the affection which he bears to his family? The
love of offspring, home, friends, in man, is then part of the same
system of contrivances of which bodily organization is another
part. And thus the author of our corporeal frame is also the author
of our capacity of kindness and resentment, of our love and of our
wish to be loved, of all the emotions which bind us to individuals,
to our families, and to our kind.
It is not necessary here to follow out and classify these emotions
and affections; or to examine how they are combined and connected
with our other motives of action, mutually giving and receiving
strength and direction. The desire of esteem, of power, of
knowledge, of society, the love of kindred, of friends, of our
country, are manifestly among the main forces by which man is urged
to act and to abstain. And as these parts of the constitution of
man are clearly intended, as we conceive, to impel him in his
appointed path; so we conceive that they are no less clearly the
work of the same great Artificer who created the heart, the eye,
the hand, the tongue, and that elemental world in which, by means
of these instruments, man pursues the objects of his appetites,
desires, and affections.
5. But if the Creator of the world be also the author of our
intellectual powers, of our feeling for the beautiful and the
sublime, of our social tendencies, and of our natural desires and
affections, we shall find it impossible not to ascribe also to Him
the higher directive attributes of our nature, the conscience and
the religious feeling, the reference of our actions to the rule of
duty and to the will of God.
It would not suit the plan of the present treatise to enter into
any detailed analysis of the connexion of these various portions
of our moral constitution. But we may observe that the existence
and universality of the conception of duty and right cannot be
doubted, however men may differ as to its original or derivative
nature. All men are perpetually led to form judgments concerning
actions, and emotions which lead to action, as right or wrong;
as what they _ought_ or _ought not_ to do or feel. There is a
faculty which approves and disapproves, acquits or condemns the
workings of our other faculties. Now, what shall we say of such
a judiciary principle, thus introduced among our motives to
action? Shall we conceive that while the other springs of action
are balanced against each other by our Creator, this, the most
pervading and universal regulator, was no part of the original
scheme? That--while the love of animal pleasures, of power, of
fame, the regard for friends, the pleasure of bestowing pleasure,
were infused into man as influences by which his course of life
was to be carried on, and his capacities and powers developed and
exercised;--this reverence for a moral law, this acknowledgment
of the obligation of duty,--a feeling which is every where found,
and which may become a powerful, a predominating motive of
action,--was given for no purpose, and belongs not to the design?
Such an opinion would be much as if we should acknowledge the
skill and contrivance manifested in the other parts of a ship, but
should refuse to recognize the rudder as exhibiting any evidence
of a purpose. Without the reverence which the opinion of right
inspires, and the scourge of general disapprobation inflicted on
that which is accounted wicked, society could scarcely go on; and
certainly the feelings and thoughts and characters of men could
not be what they are. Those impulses of nature which involve no
acknowledgment of responsibility, and the play and struggle of
interfering wishes, might preserve the species in some shape of
existence, as we see in the case of brutes. But a person must be
strangely constituted, who, living amid the respect for law, the
admiration for what is good, the order and virtues and graces of
civilized nations, (all which have their origin in some degree in
the feeling of responsibility) can maintain that all these are
casual and extraneous circumstances, no way contemplated in the
formation of man; and that a condition in which there should be
obligation in law, no merit in self-restraint, no beauty in virtue,
is equally suited to the powers and the nature of man, and was
equally contemplated when those powers were given him.
If this supposition be too extravagant to be admitted, as
it appears to be, it remains then that man, intended, as we
have already seen from his structure and properties, to be
a discoursing, social being, acting under the influence of
affections, desires, and purposes, was also intended to act under
the influence of a sense of duty; and that the acknowledgment of
the obligation of a moral law is as much part of his nature, as
hunger or thirst, maternal love or the desire of power; that,
therefore, in conceiving man as the work of a Creator, we must
imagine his powers and character given him with an intention on
the Creator’s part that this sense of duty should occupy its place
in his constitution as an active and thinking being: and that this
directive and judiciary principle is a part of the work of the same
Author who made the elements to minister to the material functions,
and the arrangements of the world to occupy the individual and
social affections of his living creatures.
This principle of conscience, it may further be observed, does not
stand upon the same level as the other impulses of our constitution
by which we are prompted or restrained. By its very nature and
essence, it possesses a supremacy over all others. “Your obligation
to obey this law is its being the law of your nature. That your
conscience approves of and attests such a course of action is
itself alone an obligation. Conscience does not only offer itself
to show us the way we should walk in, but it likewise carries its
own authority with it, that it is our natural guide: the guide
assigned us by the author of our nature.”[26] That we ought to do
an action, is of itself a sufficient and ultimate answer to the
questions, _why_ we should do it?--how we are _obliged_ to do it?
The conviction of duty implies the soundest reason, the strongest
obligation, of which our nature is susceptible.
We appear then to be using only language which is well capable of
being justified, when we speak of this irresistible esteem for what
is right, this conviction of a rule of action extending beyond the
gratification of our irreflective impulses, as an impress stamped
upon the human mind by the Deity himself; a trace of His nature; an
indication of His will; an announcement of His purpose; a promise
of His favour: and though this faculty may need to be confirmed and
unfolded, instructed and assisted by other aids, it still seems to
contain in itself a sufficient intimation that the highest objects
of man’s existence are to be attained, by means of a direct and
intimate reference of his thoughts and actions to the Divine Author
of his being.
Such then is the Deity to which the researches of Natural Theology
point; and so far is the train of reflections in which we have
engaged, from being merely speculative and barren. With the
material world we cannot stop. If a superior Intelligence _have_
ordered and adjusted the succession of seasons and the structure
of the plants of the field, we must allow far more than this at
first sight would seem to imply. We must admit still greater
powers, still higher wisdom for the creation of the beasts of the
forest with their faculties; and higher wisdom still and more
transcendent attributes, for the creation of man. And when we reach
this point, we find that it is not knowledge only, not power only,
not foresight and beneficence alone, which we must attribute
to the Maker of the World; but that we must consider him as the
Author, in us, of a reverence for moral purity and rectitude; and,
if the author of such emotions in us, how can we conceive of Him
otherwise, than that these qualities are parts of his nature; and
that he is not only wise and great, and good, incomparably beyond
our highest conceptions, but also conformed in his purposes to the
rule which he thus impresses upon us, that is, Holy in the highest
degree which we can imagine to ourselves as possible.
CHAPTER II.
_On the Vastness of the Universe._
1. The aspect of the world, even without any of the peculiar lights
which science throws upon it, is fitted to give us an idea of the
greatness of the power by which it is directed and governed, far
exceeding any notions of power and greatness which are suggested by
any other contemplation. The number of human beings who surround
us--the various conditions requisite for their life, nutrition,
well-being, all fulfilled;--the way in which these conditions are
modified, as we pass in thought to other countries, by climate,
temperament, habit;--the vast amount of the human population of the
globe thus made up;--yet man himself but one among almost endless
tribes of animals;--the forest, the field, the desert, the air,
the ocean, all teeming with creatures whose bodily wants are as
carefully provided for as his;--the sun, the clouds, the winds,
all attending, as it were, on these organized beings;--a host of
beneficent energies, unwearied by time and succession, pervading
every corner of the earth;--this spectacle cannot but give the
contemplator a lofty and magnificent conception of the Author of
so vast a work, of the Ruler of so wide and rich an empire, of the
Provider for so many and varied wants, the Director and Adjuster of
such complex and jarring interests.
But when we take a more exact view of this spectacle, and aid our
vision by the discoveries which have been made of the structure and
extent of the universe, the impression is incalculably increased.
The number and variety of animals, the exquisite skill displayed
in their structure, the comprehensive and profound relations by
which they are connected, far exceed any thing which we could in
any degree have imagined. But the view of the universe expands also
on another side. The earth, the globular body thus covered with
life, is not the only globe in the universe. There are, circling
about our own sun, six others, so far as we can judge, perfectly
analogous in their nature: besides our moon and other bodies
analogous to it. No one can resist the temptation to conjecture,
that these globes, some of them much larger than our own, are
not dead and barren;--that they are, like ours, occupied with
organization, life, intelligence. To conjecture is all that we can
do, yet even by the perception of such a possibility, our view of
the kingdom of nature is enlarged and elevated. The outermost of
the planetary globes of which we have spoken is so far from the
sun, that the central luminary must appear to the inhabitants of
that planet, if any there are, no larger than Venus does to us; and
the length of their year will be eighty-two of ours.
But astronomy carries us still onwards. It teaches us that, with
the exception of the planets already mentioned, the stars which
we see have no immediate relation to our system. The obvious
supposition is that they are of the nature and order of our
sun: the minuteness of their apparent magnitude agrees, on this
supposition, with the enormous and almost inconceivable distance
which, from all the measurements of astronomers, we are led to
attribute to them. If then these are suns, they may, like our sun,
have planets revolving round them; and these may, like our planet,
be the seats of vegetable and animal and rational life:--we may
thus have in the universe worlds, no one knows how many, no one can
guess how varied:--but however many, however varied, they are still
but so many provinces in the same empire, subject to common rules,
governed by a common power.
But the stars which we see with the naked eye are but a very small
portion of those which the telescope unveils to us. The most
imperfect telescope will discover some that are invisible without
it; the very best instrument perhaps does not show us the most
remote. The number which crowds some parts of the heavens is truly
marvellous. Dr. Herschel calculated that a portion of the milky
way, about ten degrees long and two and a half broad, contained two
hundred and fifty-eight thousand. In a sky so occupied, the moon
would eclipse two thousand of such stars at once.
We learn too from the telescope that even in this province the
variety of nature is not exhausted. Not only do the stars differ in
colour and appearance, but some of them grow periodically fainter
and brighter, as if they were dark on one side, and revolved on
their axes. In other cases two stars appear close to each other,
and in some of these cases it has been clearly established,
that the two have a motion of revolution about each other; thus
exhibiting an arrangement before unguessed, and giving rise,
possibly, to new conditions of worlds. In other instances again,
the telescope shows, not luminous points, but extended masses of
dilute light, like bright clouds, hence called _nebulæ_. Some
have supposed (as we have noticed in the last book) that such
nebulæ by further condensation might become suns; but for such
opinions we have nothing but conjecture. Some stars again have
undergone permanent changes, or have absolutely disappeared, as the
celebrated star of 1572, in the constellation Cassiopea.
If we take the whole range of created objects in our own system,
from the sun down to the smallest animalcule, and suppose such a
system, or something in some way analogous to it, to be repeated
for each of the millions of stars thus revealed to us, we have a
representation of the material part of the universe, according to a
view which many minds receive as a probable one; and referring this
aggregate of systems to the Author of the universe, as in our own
system we have found ourselves led to do, we have thus an estimate
of the extent to which his creative energy would thus appear to
have been exercised in the material world.
If we consider further the endless and admirable contrivances and
adaptations which philosophers and observers have discovered in
every portion of our own system, every new step of our knowledge
showing us something new in this respect; and if we combine this
consideration with the thought how small a portion of the universe
our knowledge includes, we shall, without being able at all to
discern the extent of the skill and wisdom thus displayed, see
something of the character of the design, and of the copiousness
and ampleness of the means which the scheme of the world exhibits.
And when we see that the tendency of all the arrangements which
we can comprehend is to support the existence, to develope the
faculties, to promote the well-being of these countless species of
creatures; we shall have some impression of the beneficence and
love of the Creator, as manifested in the physical government of
his creation.
2. It is extremely difficult to devise any means of bringing
before a common apprehension the scale on which the universe is
constructed, the enormous proportion which the larger dimensions
bear to the smaller, and the amazing number of steps from large to
smaller, or from small to larger, which the consideration of it
offers. The following comparative representations may serve to
give the reader to whom the subject is new some idea of these steps.
If we suppose the earth to be represented by a globe a foot in
diameter, the distance of the sun from the earth will be about two
miles; the diameter of the sun, on the same supposition, will be
something above one hundred feet, and consequently his bulk such
as might be made up of two hemispheres, each about the size of the
dome of St. Paul’s. The moon will be thirty feet from us, and her
diameter three inches, about that of a cricket ball. Thus the sun
would much more than occupy all the space within the moon’s orbit.
On the same scale, Jupiter would be above ten miles from the sun,
and Uranus forty. We see then how thinly scattered through space
are the heavenly bodies. The fixed stars would be at an unknown
distance, but, probably, if all distances were thus diminished, no
star would be nearer to such a one-foot earth, than the moon now is
to us.
On such a terrestrial globe the highest mountains would be
about an eightieth of an inch high, and consequently only just
distinguishable. We may imagine therefore how imperceptible would
be the largest animals. The whole organized covering of such a
globe would be quite undiscoverable by the eye, except perhaps by
colour, like the bloom on a plum.
In order to restore this earth and its inhabitants to their true
dimensions, we must magnify them forty millions of times; and to
preserve the proportions, we must increase equally the distances
of the sun and of the stars from us. They seem thus to pass off
into infinity; yet each of them thus removed, has its system of
mechanical and perhaps of organic processes going on upon its
surface.
But the arrangements of organic life which we can see with the
naked eye are few, compared with those which the microscope
detects. We know that we may magnify objects thousands of times,
and still discover fresh complexities of structure; if we suppose,
therefore, that we increase every particle of matter in our
universe in such a proportion, in length, breadth, and thickness,
we may conceive that we tend thus to bring before our apprehension
a true estimate of the quantity of organized adaptations which are
ready to testify the extent of the Creator’s power.
3. The other numerical quantities which we have to consider in
the phenomena of the universe are on as gigantic a scale as the
distances and sizes. By the rotation of the earth on its axis, the
parts of the equator move at the rate of a thousand miles an hour,
and the portions of the earth’s surface which are in our latitude,
at about six hundred. The former velocity is nearly that with
which a cannon ball is discharged from the mouth of a gun; but,
large as it is, it is inconsiderable compared with the velocity
of the earth in its orbit about the sun. This latter velocity is
sixty-five times the former. By the rotatory motion of the earth,
a point of its surface is carried sometimes forwards and sometimes
backwards with regard to the annual progression; but in consequence
of the great predominance of the latter velocity in amount, the
former scarcely affects it either way. And even the latter velocity
is inconsiderable compared with that of light; which comparison,
however, we shall not make; since, according to the theory we have
considered as most probable, the motion of light is not a transfer
of matter but of motion from one part of space to another.
The extent of the scale of density of different substances has
already been mentioned; gold is twenty times as heavy as water; air
is eight hundred and thirty times lighter, steam eight thousand
times lighter than water; the luminiferous ether is incomparably
rarer than steam: and this is true of the matter of light, whether
we adopt the undulatory theory or any other.
4. The above statements are vast in amount, and almost oppressive
to our faculties. They belong to the measurement of the powers
which are exerted in the universe, and of the spaces through which
their efficacy reaches (for the most distant bodies are probably
connected both by gravity and light.) But these estimates cannot be
said so much to give us any notion of the powers of the Deity, as
to correct the errors we should fall into by supposing his powers
at all to resemble ours:--by supposing that numbers, and spaces,
and forces, and combinations, which would overwhelm us, are any
obstacle to the arrangements which his plan requires. We can easily
understand that to an intelligence surpassing ours in degree only,
that may be easy which is impossible to us. The child who cannot
count beyond four, the savage who has no name for any number above
five, cannot comprehend the possibility of dealing with thousands
and millions: yet a little additional developement of the intellect
makes such numbers manageable and conceivable. The difficulty
which appears to reside in numbers and magnitudes and stages of
subordination, is one produced by judging from ourselves--by
measuring with our own sounding line; when that reaches no bottom,
the ocean appears unfathomable. Yet in fact, how is a hundred
millions of miles a _great_ distance? how is a hundred millions
of times a _great_ ratio? Not in itself: this _greatness_ is no
quality of the numbers which can be proved like their mathematical
properties; on the contrary, all that absolutely belongs to number,
space, and ratio, must, we know demonstrably, be equally true of
the largest and the smallest. It is clear that the _greatness_ of
these expressions of measure has reference to _our_ faculties only.
Our astonishment and embarrassment take for granted the limits
of our own nature. We have a tendency to treat a difference of
degree and of addition, as if it were a difference of kind and of
transformation. The existence of the attributes, design, power,
goodness, is a matter depending on obvious grounds: about these
qualities there can be no mistake: if we can know any thing, we
can know these attributes when we see them. But the extent, the
limits of such attributes must be determined by their effects; our
knowledge of their limits by what we see of the effects. Nor is any
extent, any amount of power and goodness improbable beforehand: we
know that these must be great, we cannot tell how great. We should
not expect beforehand to find them bounded; and therefore when the
boundless prospect opens before us, we may be bewildered, but we
have no reason to be shaken in our conviction of the reality of
the cause from which their effects proceed: we may feel ourselves
incapable of following the train of thought, and may stop, but we
have no rational motive for quitting the point which we have thus
attained in tracing the Divine Perfections.
On the contrary, those magnitudes and proportions which leave our
powers of conception far behind;--that ever-expanding view which
is brought before us, of the scale and mechanism, the riches and
magnificence, the population and activity of the universe;--may
reasonably serve, not to disturb, but to enlarge and elevate our
conceptions of the Maker and Master of all; to feed an ever-growing
admiration of His wonderful nature; and to excite a desire to be
able to contemplate more steadily and conceive less inadequately
the scheme of his government and the operation of his power.
CHAPTER III.
_On Man’s Place in the Universe._
The mere aspect of the starry heavens, without taking into account
the view of them to which science introduces us, tends strongly
to force upon man the impression of his own insignificance. The
vault of the sky arched at a vast and unknown distance over our
heads; the stars, apparently infinite in number, each keeping its
appointed place and course, and seeming to belong to a wide system
of things which has no relation to the earth; while man is but one
among many millions of the earth’s inhabitants;--all this makes
the contemplative spectator feel how exceedingly small a portion
of the universe he is; how little he must be, in the eyes of an
intelligence which can embrace the whole. Every person, in every
age and country, will recognize as irresistibly natural the train
of thought expressed by the Hebrew psalmist: “when I consider the
heavens the work of thy hands--the moon and the stars which thou
hast ordained--Lord what is man that thou art mindful of him, or
the son of man that thou regardest him?”
If this be the feeling of the untaught person, when he contemplates
the aspect of the skies, such as they offer themselves to a
casual and unassisted glance, the impression must needs be
incalculably augmented, when we look at the universe with the aid
of astronomical discovery and theory. We then find, that a few of
the shining points which we see scattered on the face of the sky
in such profusion, appear to be of the same nature as the earth,
and may perhaps, as analogy would suggest, be like the earth, the
habitations of organized beings;--that the rest of “the host of
heaven” may, by a like analogy, be conjectured to be the centres of
similar systems of revolving worlds;--that the vision of man has
gone travelling onwards, to an extent never anticipated, through
this multitude of systems, and that while myriads of new centres
start up at every advance, he appears as yet not to have received
any intimation of a limit. Every person probably feels, at first,
lost, confounded, overwhelmed, with the vastness of this spectacle;
and seems to himself, as it were, annihilated by the magnitude
and multitude of the objects which thus compose the universe.
The distance between him and the Creator of the world appears to
be increased beyond measure by this disclosure. It seems as if a
single individual could have no chance and no claim for the regard
of the Ruler of the whole.
The mode in which the belief of God’s government of the physical
world is important and interesting to man, is, as has already
been said, through the connexion which this belief has with the
conviction of God’s government of the moral world; this latter
government being, from its nature, one which has a personal
relation to each individual, his actions and thoughts. It will,
therefore, illustrate our subject to show that this impression
of the difficulty of a personal superintendence and government,
exercised by the Maker of the world over each of his rational and
free creatures, is founded upon illusory views; and that on an
attentive and philosophical examination of the subject, such a
government is in accordance with all that we can discover of the
scheme and the scale of the universe.
1. We may, in the first place, repeat the observation made in
the last chapter, on the confusion which sometimes arises in our
minds, and makes us consider the number of the objects of the
Divine care as a difficulty in the way of its exercise. If we
can conceive this care employed on a million of persons, on the
population of a kingdom, of a city, of a street, there is no real
difficulty in supposing it extended to every planet in the solar
system, admitting each to be peopled as ours is; nor to every
part of the universe, supposing each star the centre of such a
system. _Numbers_ are nothing in themselves; and when we reject the
known, but unessential limits of our own faculties, it is quite as
allowable to suppose a million millions of earths, as one, to be
under the moral government of God.
2. In the next place we may remark, not only that no reason can be
assigned why the Divine care should not extend to a much greater
number of individuals than we at first imagine, but that in fact
we know that it _does_ so extend. It has been well observed, that
about the same time when the invention of the telescope showed us
that there might be myriads of other worlds claiming the Creator’s
care; the invention of the microscope proved to us that there were
in our own world myriads of creatures, before unknown, which this
care was preserving. While one discovery seemed to remove the
Divine Providence further from us, the other gave us most striking
examples that it was far more active in our neighbourhood than we
had supposed: while the first extended the boundaries of God’s
known kingdom, the second made its known administration more minute
and careful. It appeared that in the leaf and in the bud, in solids
and in fluids, animals existed hitherto unsuspected; the apparently
dead masses and blank spaces of the world were found to swarm with
life. And yet, of the animals thus revealed, all, though unknown to
us before, had never been forgotten by Providence. Their structure,
their vessels and limbs, their adaptation to their situation, their
food and habitations, were regulated in as beautiful and complete
a manner as those of the largest and apparently most favoured
animals. The smallest insects are as exactly finished, often as
gaily ornamented, as the most graceful beasts or the birds of
brightest plumage. And when we seem to go out of the domain of the
complex animal structure with which we are familiar, and come to
animals of apparently more scanty faculties, and less developed
powers of enjoyment and action, we still find that their faculties
and their senses are in exact harmony with their situation and
circumstances; that the wants which they have are provided for, and
the powers which they possess called into activity. So that Müller,
the patient and accurate observer of the smallest and most obscure
microscopical animalcula, declares that all classes alike, those
which have manifest organs, and those which have not, offer a vast
quantity of new and striking views of the animal economy; every
step of our discoveries leading us to admire the design and care
of the Creator.[27] We find, therefore, that the Divine Providence
is, in fact, capable of extending itself adequately to an immense
succession of tribes of beings, surpassing what we can imagine or
could previously have anticipated; and thus we may feel secure, so
far as analogy can secure us, that the mere multitude of created
objects cannot remove us from the government and superintendence of
the Creator.
3. We may observe further, that, vast as are the parts and
proportions of the universe, we still appear to be able to perceive
that it is _finite_; the subordination of magnitudes and numbers
and classes appears to have its limits. Thus, for any thing which
we can discover, the sun is the largest body in the universe;
and at any rate, bodies of the order of the sun are the largest
of which we have any evidence: we know of no substance denser
than gold, and it is improbable that one denser, or at least much
denser, should ever be detected: the largest animals which exist
in the sea and on the earth are almost certainly known to us. We
may venture also to say, that the smallest animals which possess
in their structure a clear analogy with larger ones, have been
already seen. Many of the animals which the microscope detects, are
as complete and complex in their organization as those of larger
size: but beyond a certain point, they appear, as they become
more minute, to be reduced to a homogeneity and simplicity of
composition which almost excludes them from the domain of animal
life. The smallest microscopical objects which can be supposed
to be organic, are points,[28] or gelatinous globules,[29] or
threads,[30] in which no distinct organs, interior or exterior,
can be discovered. These, it is clear, cannot be considered as
indicating an indefinite progression of animal life in a descending
scale of minuteness. We can, mathematically speaking, conceive one
of these animals as perfect and complicated in its structure as
an elephant or an eagle, but we do not find it so in nature. It
appears, on the contrary, in these objects, as if we were, at a
certain point of magnitude, reaching the boundaries of the animal
world. We need not here consider the hypotheses and opinions to
which these ambiguous objects have given rise; but, without any
theory, they tend to show that the subordination of organic life is
finite on the side of the little as well as of the great.
Some persons might, perhaps, imagine that a ground for believing
the smallness of organized beings to be limited, might be found in
what we know of the constitution of matter. If solids and fluids
consist of particles of a definite, though exceeding smallness,
which cannot further be divided or diminished, it is manifest
that we have, in the smallness of these particles, a limit to the
possible size of the vessels and organs of animals. The fluids
which are secreted, and which circulate in the body of a mite, must
needs consist of a vast number of particles, or they would not be
fluids: and an animal might be so much smaller than a mite, that
its tubes could not contain a sufficient collection of the atoms
of matter, to carry on its functions. We should, therefore, of
necessity reach a limit of minuteness in organic life, if we could
demonstrate that matter is composed of such indivisible atoms. We
shall not, however, build any thing on this argument; because,
though the _atomic theory_ is sometimes said to be proved, what is
proved is, that chemical and other effects take place as if they
were the aggregate of the effects of certain particles of elements,
the _proportions_ of which particles are fixed and definite; but
that any limit can be assigned to the smallness of these particles,
has never yet been made out. We prefer, therefore, to rest the
proof of the finite extent of animal life, as to size, on the
microscopical observations previously referred to.
Probably we cannot yet be said to have reached the limit of the
universe with the power of our telescopes; that is, it does
not appear that telescopes have yet been used, so powerful in
exhibiting small stars, that we can assume that more powerful
instruments would not discover new stars. Whether or no, however,
this degree of perfection has been reached, we have no proof that
it does not exist; if it were once obtained we should have, with
some approximation, the limit of the universe as to the number of
worlds, as we have already endeavoured to show we have obtained
the limits with regard to the largeness and smallness of the
inhabitants of our own world.
In like manner, although the discovery of new species in some of
the kingdoms of nature has gone on recently with enormous rapidity,
and to an immense extent;--for instance in botany, where the
species known in the time of Linnæus were about ten thousand, and
are now probably fifty thousand;--there can be no doubt that the
number of species and genera is really limited; and though a great
extension of our knowledge is required to reach these limits, it
is our ignorance merely, and not their nonexistence, which removes
them from us.
In the same way it would appear that the universe, so far as it
is an object of our knowledge, is finite in other respects also.
Now when we have once attained this conviction, all the oppressive
apprehension of being overlooked in the government of the universe
has no longer any rational source. For in the superintendence
of a finite system of things, what is there which can appear
difficult or overwhelming to a Being such as we must, from what
we know, conceive the Creator to be? Difficulties arising from
space, number, gradation, are such as we can conceive _ourselves_
capable of overcoming, merely by an extension of our present
faculties. Is it not then easy to imagine that such difficulties
must vanish before Him who made us and our faculties? Let it be
considered how enormous a proportion the largest work of man bears
to the smallest;--the great pyramid to the point of a needle. This
comparison does not overwhelm us, because we know that man has
made both. Yet the difference between this proportion and that of
the sun to the claw of a mite, does not at all correspond to the
difference which we must suppose to obtain between the Creator and
the creature. It appears then that, if the first flash of that view
of the universe which science reveals to us, does sometimes dazzle
and bewilder men, a more attentive examination of the prospect, by
the light we thus obtain, shows us how unfounded is the despair
of our being the objects of Divine Providence, how absurd the
persuasion that we have discovered the universe to be too large for
its ruler.
4. Another ground of satisfactory reflection, having the same
tendency, is to be found in the admirable order and consistency,
the subordination and proportion of parts, which we find to prevail
in the universe, as far as our discoveries reach. We have, it
may be, a multitude almost innumerable of worlds, but no symptom
of crowding, of confusion, of interference. All such defects are
avoided by the manner in which these worlds are distributed into
systems;--these systems, each occupying a vast space, but yet
disposed at distances before which their own dimensions shrink
into insignificance;--all governed by one law, yet this law so
concentrating its operation on each system, that each proceeds as
if there were no other, and so regulating its own effects that
perpetual change produces permanent uniformity. This is the kind of
harmonious relation which we perceive in that part of the universe,
the mechanical part namely, the laws of which are best known to
us. In other provinces, where our knowledge is more imperfect, we
can see glimpses of a similar vastness of combination, producing,
by its very nature, completeness of detail. Any analogy by which
we can extend such views to the moral world, must be of a very
wide and indefinite kind; yet the contemplation of this admirable
relation of the arrangements of the physical creation, and the
perfect working of their laws, is well calculated to give us
confidence in a similar beauty and perfection in the arrangements
by which our moral relations are directed, our higher powers and
hopes unfolded. We may readily believe that there is, in this part
of the creation also, an order, a subordination of some relations
to others, which may remove all difficulty arising from the vast
multitude of moral agents and actions, and make it possible that
the superintendence of the moral world shall be directed with as
exact a tendency to moral good, as that by which the government of
the physical world is directed to physical good.
We may perhaps see glimpses of such an order, in the arrangements
by which our highest and most important duties depend upon our
relation to a small circle of persons immediately around us: and
again, in the manner in which our acting well or ill results from
the operation of a few principles within us; as our conscience, our
desire of moral excellence, and of the favour of God. We can hardly
consider such principles otherwise than as intended to occupy
their proper place in the system by which man’s destination is to
be determined; and thus, as among the means of the government and
superintendence of God in the moral world.
That there must be an order and a system to which such regulative
principles belong, the whole analogy of creation compels us to
believe. It would be strange indeed, if, while the mechanical
world, the system of inert matter, is so arranged that we
cannot contemplate its order without an elevated intellectual
pleasure;--while organized life has no faculties without their
proper scope, no tendencies without their appointed object;--the
rational faculties and moral tendencies of man should belong to no
systematic order, should operate with no corresponding purpose:
that, while the perception of sweet and bitter has its acknowledged
and unmistakeable uses, the universal perception of right and
wrong, the unconquerable belief of the merit of certain feelings
and actions, the craving alike after moral advancement and after
the means of attaining it, should exist only to delude, perplex,
and disappoint man. No one, with his contemplations calmed and
filled and harmonized by the view of the known constitution of
the universe, its machinery “wheeling unshaken” in the farthest
skies and in the darkest cavern, its vital spirit breathing alike
effectively in the veins of the philosopher and the worm;--no one,
under the influence of such a train of contemplations, can possibly
admit into his mind a persuasion which makes the moral part of
our nature a collection of inconsistent and futile impressions,
of idle dreams and warring opinions, each having the same claims
to our acceptance. Wide as is the distance between the material
and the moral world; shadowy as all reasonings necessarily are
which attempt to carry the inferences of one into the other;
elevated above the region of matter as all the principles and
grounds of truth must be, which belong to our responsibilities
and hopes; still the astronomical and natural philosopher can
hardly fail to draw from their studies an imperturbable conviction
that our moral nature cannot correspond to those representations
according to which it has no law, coherency, or object. The mere
natural reasoner may, or must stop far short of all that it is
his highest interest to know, his first duty to pursue; but even
he, if he take any elevated and comprehensive views of his own
subject, must escape from the opinions, as unphilosophical as they
are comfortless, which would expel from our view of the world
all reference to duty and moral good, all reliance on the most
universal grounds of trust and hope.
Men’s belief of their duty, and of the reasons for practising it,
connected as it is with the conviction of a personal relation to
their Maker, and of His power of superintendence and reward, is as
manifest a fact in the moral, as any that can be pointed out is
in the natural world. By mere analogy which has been intimated,
therefore, we cannot but conceive that this fact belongs in some
manner or other to the order of the moral world, and of its
government.
When any one acknowledges a moral governor of the world; perceives
that domestic and social relations are perpetually operating and
seem intended to operate, to retain and direct men in the path of
duty; and feels that the voice of conscience, the peace of heart
which results from a course of virtue, and the consolations of
devotion, are ever ready to assume their office as our guides
and aids in the conduct of all our actions;--he will probably be
willing to acknowledge also that the means of moral government
are not wanting, and will no longer be oppressed or disturbed by
the apprehension that the superintendence of the world may be
too difficult for its Ruler, and that any of His subjects and
servants may be overlooked. He will no more fear that the moral
than that the physical laws of God’s creation should be forgotten
in any particular case: and as he knows that every sparrow which
falls to the ground contains in its structure innumerable marks
of the Divine care and kindness, he will be persuaded that every
individual, however apparently humble and insignificant, will have
his moral being dealt with according to the laws of God’s wisdom
and love; will be enlightened, supported, and raised, if he use the
appointed means which God’s administration of the world of moral
light and good offers to his use.
CHAPTER IV.
_On the Impression produced by the Contemplation of Laws of
Nature; or, on the Conviction that Law implies Mind._
The various trains of thought and reasoning which lead men from
a consideration of the natural world to the conviction of the
existence, the power, the providence of God, do not require, for
the most part, any long or laboured deduction, to give them their
effect on the mind. On the contrary, they have, in every age and
country, produced their impression on multitudes who have not
instituted any formal reasonings upon the subject, and probably
upon many who have not put their conclusions in the shape of any
express propositions. The persuasion of a superior intelligence and
will, which manifests itself in every part of the material world,
is, as is well known, so widely diffused and deeply infixed, as to
have made it a question among speculative men whether the notion
of such a power is not universal and innate. It is our business to
show only how plainly and how universally such a belief results
from the study of the appearances about us. That in many nations,
in many periods, this persuasion has been mixed up with much that
was erroneous and perverse in the opinions of the intellect or
the fictions of fancy, does not weaken the force of such consent.
The belief of a supernatural and presiding power runs through all
these errors: and while the perversions are manifestly the work
of caprice and illusion, and vanish at the first ray of sober
inquiry, the belief itself is substantial and consistent, and grows
in strength upon every new examination. It was the firmness and
solidity of the conviction of _something_ Divine which gave a
hold and permanence to the figments of so many false divinities.
And those who have traced the progress of human thought on other
subjects, will not think it strange, that while the fundamental
persuasion of a Deity was thus irremovably seated in the human
mind, the developement of this conception into a consistent, pure,
and steadfast belief in one Almighty and Holy Father and God,
should be long missed, or never attained, by the struggle of the
human faculties; should require long reflection to mature it, and
the aid of revelation to establish it in the world.
The view of the universe which we have principally had occasion to
present to the reader, is that in which we consider its appearances
as reducible to certain fixed and general laws. Availing ourselves
of some of the lights which modern science supplies, we have
endeavoured to show that the adaptation of such laws to each other,
and their fitness to promote the harmonious and beneficial course
of the world, may be traced, wherever we can discover the laws
themselves; and that the conceptions of the Divine Power, Goodness
and Superintendence which we thus form, agree in a remarkable
manner with the views of the Supreme Being, to which reason,
enlightened by the divine revelation, has led.
But we conceive that the general impressions of mankind would
go further than a mere assent to the argument as we have thus
stated it. To most persons it appears that the mere existence of
a law connecting and governing any class of phenomena, implies a
presiding intelligence which has preconceived and established the
law. When events are regulated by precise rules of time and space,
of number and measure, men conceive these rules to be the evidence
of thought and mind, even without discovering in the rules any
peculiar adaptations, or without supposing their purpose to be
known.
The origin and the validity of such an impression on the human
mind may appear to some matters of abstruse and doubtful
speculation: yet the tendency to such a belief prevails strongly
and widely, both among the common class of minds whose thoughts
are casually and unsystematically turned to such subjects, and
among philosophers to whom laws of nature are habitual subjects
of contemplation. We conceive therefore that such a tendency may
deserve to be briefly illustrated; and we trust also that some
attention to this point may be of service in throwing light upon
the true relation of the study of nature to the belief in God.
1. A very slight attention shows us how readily order and
regularity suggest to a common apprehension the operation of a calm
and untroubled intelligence presiding over the course of events.
Thus the materialist poet, in accounting for the belief in the
Gods, though he does not share it, cannot deny the habitual effect
of this manifestation.
Præterea cœli rationes _ordine certo_
Et _varia_ annorum cernebant _tempora_ vorti;
Nec poterant quibus id fieret cognoscere caussis.
Ergo perfugium sibi habebant Omnia Divis
Tradere et illorum nutu facere omnia flecti.
LUCRET. v. 1182.
They saw the skies in constant order run,
The varied seasons and the circling sun,
Apparent rule, with unapparent cause,
And thus they sought in Gods the source of laws.
The same feeling may be traced in the early mythology of a large
portion of the globe. We might easily, taking advantage of the
labours of learned men, exemplify this in the case of the oriental
nations, of Greece, and of many other countries. Nor does there
appear much difficulty in pointing out the error of those who
have maintained that all religion had its _origin_ in the worship
of the stars and the elements; and who have insinuated that all
such impressions are unfounded, inasmuch as these are certainly
not right objects of human worship. The religious feeling, the
conviction of a supernatural power, of an intelligence connecting
and directing the phenomena of the world, had not its _origin_
in the worship of sun, or stars, or elements; but was itself the
necessary though unexpressed foundation of all worship, and all
forms of false, as well as true, religion. The contemplation of
the earth and heavens called into action this religious tendency
in man; and to say that the worship of the material world formed
or suggested this religious feeling, is to invert the order of
possible things in the most unphilosophical manner. Idolatry is
not the source of the belief in God, but is a compound of the
persuasion of a supernatural government, with certain extravagant
and baseless conceptions as to the manner in which this government
is exercised.
We will quote a passage from an author who has illustrated at
considerable length the hypothesis that all religious belief is
derived from the worship of the elements.
“Light, and darkness its perpetual contrast; the succession of
days and nights, the periodical order of the seasons; the career
of the brilliant luminary which regulates their course; that of
the moon his sister and rival; night, and the innumerable fires
which she lights in the blue vault of heaven; the revolutions of
the stars, which exhibit them for a longer or a shorter period
above our horizon; the constancy of this period in the fixed stars,
its variety in the wandering stars, the planets; their direct and
retrograde course, their momentary rest; the phases of the moon
waxing, full, waning, divested of all light; the progressive motion
of the sun upwards, downwards; the successive order of the rising
and setting of the fixed stars, which mark the different points of
the course of the sun, while the various aspects which the earth
itself assumes mark, here below also, the same periods of the sun’s
annual motion; * * * all these different pictures, displayed before
the eyes of man, formed the great and magnificent spectacle by
which I suppose him surrounded at the moment when _he is about to
create his gods_.”[31]
What is this (divested of its wanton levity of expression) but to
say, that when man has so far traced the course of nature as to be
irresistibly impressed with the existence of order, law, variety in
constancy, and fixity in change; of relations of form and space,
duration and succession, cause and consequence, among the objects
which surround him; there springs up in his breast, unbidden
and irresistibly, the thought of superintending intelligence,
of a mind which comprehended from the first and completely that
which he late and partially comes to know? The worship of earth
and sky, of the host of heaven and the influences of nature, is
not the ultimate and fundamental fact in the early history of
the religious impressions of mankind. These are but derivative
streams, impure and scanty, from the fountain of religious feeling
which appears to be disclosed to us by the contemplation of the
universe, as the seat of law and the manifestation of intellect.
Time suggests to man the thought of eternity; space of infinity;
law of intelligence; order of purpose; and however difficult and
long a task it may be to develope these suggestions into clear
convictions, these thoughts are the real parents of our natural
religious belief. The only relation between true religion and
the worship of the elemental world is, that the latter is the
partial and gross perversion, the former the consistent and pure
developement of the same original idea.
2. The connexion of the laws of the material world with an
intelligence which preconceived and instituted the law, which
is thus, as we perceive, so generally impressed on the common
apprehension of mankind, has also struck no less those who have
studied nature with a more systematic attention, and with the
peculiar views which belong to science. The laws which such
persons learn and study, seem, indeed, most naturally to lead to
the conviction of an intelligence which originally gave to the law
its form.
What we call a general law is, in truth, a form of expression
including a number of facts of like kind. The facts are separate;
the unity of view by which we associate them, the character of
generality and of law, resides in those relations which are the
object of the intellect. The law once apprehended by us, takes
in our minds the place of the facts themselves, and is said to
_govern_ or determine them, because it determines our anticipations
of what they will be. But we cannot, it would seem, conceive a law,
founded on such intelligible relations, to govern and determine
the facts themselves, any otherwise than by supposing also an
intelligence by which these relations are contemplated, and these
consequences realized. We cannot then represent to ourselves the
universe governed by general laws otherwise than by conceiving an
intelligent and conscious Deity, by whom these laws were originally
contemplated, established, and applied.
This perhaps will appear more clear, when it is considered that
the laws of which we speak are often of an abstruse and complex
kind, depending upon relations of space, time, number, and other
properties, which we perceive by great attention and thought.
These relations are often combined so variously and curiously,
that the most subtle reasonings and calculations which we can form
are requisite in order to trace their results. Can such laws be
conceived to be instituted without any exercise of knowledge and
intelligence? Can material objects apply geometry and calculation
to themselves? Can the lenses of the eye, for instance, be formed
and adjusted with an exact suitableness to their refractive
powers, while there is in the agency which has framed them, no
consciousness of the laws of light, of the course of rays, of
the visible properties of things? This appears to be altogether
inconceivable.
Every particle of matter possesses an almost endless train of
properties, each acting according to its peculiar and fixed
laws. For every atom of the same kind of matter these laws are
invariably and perpetually the same, while for the different kinds
of matter the difference of these properties is equally constant.
This constant and precise resemblance, this variation equally
constant and equally regular, suggest irresistibly the conception
of some cause, independent of the atoms themselves, by which their
similarity and dissimilarity, the agreement and difference of their
deportment under the same circumstances, have been determined. Such
a view of the constitution of matter, as is observed by an eminent
writer of our own time, effectually destroys the idea of its
eternal and self-existent nature, “by giving to each of its atoms
the essential characters, at once, of a _manufactured article_ and
a _subordinate agent_.”[32]
That such an impression, and the consequent belief in a divine
Author of the universe, by whom its laws were ordained and
established, does result from the philosophical contemplation of
nature, will, we trust, become still more evident by tracing the
effect produced upon men’s minds by the discovery of such laws and
properties as those of which we have been speaking; and we shall
therefore make a few observations on this subject.
CHAPTER V.
_On Inductive Habits; or, on the Impression produced on Men’s Minds
by discovering Laws of Nature._
The object of physical science is to discover such laws and
properties as those of which we have spoken in the last chapter.
In this task, undoubtedly a progress has been made on which we may
well look with pleasure and admiration; yet we cannot hesitate to
confess that the extent of our knowledge on such subjects bears no
proportion to that of our ignorance. Of the great and comprehensive
laws which rule over the widest provinces of natural phenomena, few
have yet been disclosed to us. And the names of the philosophers,
whose high office it has been to detect such laws, are even yet far
from numerous. In looking back at the path by which science has
advanced to its present position, we see the names of the great
discoverers shine out like luminaries, few and scattered along the
line: by far the largest portion of the space is occupied by those
whose comparatively humble office it was to verify, to develope, to
apply the general truths which the discoverers brought to light.
It will readily be conceived that it is no easy matter, if it be
possible, to analyse the process of thought by which laws of nature
have thus been discovered; a process which, as we have said, has
been in so few instances successfully performed. We shall not here
make any attempt at such an analysis. But without this, we conceive
it may be shown that the constitution and employment of the mind
on which such discoveries depend, are friendly to that belief in
a wise and good Creator and Governor of the world, which it has
been our object to illustrate and confirm. And if it should appear
that those who see further than their fellows into the bearings
and dependencies of the material things and elements by which they
are surrounded, have also been, in almost every case, earnest and
forward in acknowledging the relation of all things to a supreme
intelligence and will; we shall be fortified in our persuasion
that the true scientific perception of the general constitution
of the universe, and of the mode in which events are produced and
connected, is fitted to lead us to the conception and belief of God.
Let us consider for a moment what takes place in the mind of a
student of nature when he attains to the perception of a law
previously unknown, connecting the appearances which he has
studied. A mass of facts which before seemed incoherent and
unmeaning, assume, on a sudden, the aspect of connexion and
intelligible order. Thus, when Kepler discovered the law which
connects the periodic times with the diameters of the planetary
orbits; or, when Newton showed how this and all other known
mathematical properties of the solar system were included in the
law of universal gravitation according to the inverse square of
the distance; particular circumstances which, before, were merely
matter of independent record, became, from that time, indissolubly
conjoined by the laws so discovered. The separate occurrences and
facts, which might hitherto have seemed casual and without reason,
were now seen to be all exemplifications of the same truth. The
change is like that which takes place when we attempt to read a
sentence written in difficult or imperfect characters. For a time
the separate parts appear to be disjointed and arbitrary marks; the
suggestions of possible meanings, which succeed each other in the
mind, fail, as fast as they are tried, in combining or accounting
for these symbols: but at last the true supposition occurs; some
words are found to coincide with the meaning thus assumed; the
whole line of letters appear to take definite shapes and to leap
into their proper places; and the truth of the happy conjecture
seems to flash upon us from every part of the inscription.
The discovery of laws of nature, truly and satisfactorily
connecting and explaining phenomena, of which, before, the
connexion and causes had been unknown, displays much of a similar
process, of obscurity succeeded by evidence, of effort and
perplexity followed by conviction and repose. The innumerable
conjectures and failures, the glimpses of light perpetually
opening and as often clouded over, the unwearied perseverance and
inexhaustible ingenuity exercised by Kepler in seeking for the
laws which he finally discovered, are, thanks to his communicative
disposition, curiously exhibited in his works, and have been
narrated by his biographers; and such efforts and alternations,
modified by character and circumstances, must generally precede
the detection of any of the wider laws and dependencies by which
the events of the universe are regulated. We may readily conceive
the satisfaction and delight with which, after this perplexity and
struggle, the discoverer finds himself in light and tranquillity;
able to look at the province of nature which has been the subject
of his study, and to read there an intelligible connexion, a
sufficing reason, which no one before him had understood or
apprehended.
This step so much resembles the mode in which one intelligent being
understands and apprehends the conceptions of another, that we
cannot be surprised if those persons in whose minds such a process
has taken place, have been most ready to acknowledge the existence
and operation of a superintending intelligence, whose ordinances it
was their employment to study. When they had just read a sentence
of the table of the laws of the universe, they could not doubt
whether it had had a legislator. When they had deciphered there a
comprehensive and substantial truth, they could not believe that
the letters had been thrown together by chance. They could not but
readily acknowledge that what their faculties had enabled them to
read, must have been written by some higher and profounder mind.
And accordingly, we conceive it will be found, on examining the
works of those to whom we owe our knowledge of the laws of nature,
and especially of the wider and more comprehensive laws, that
such persons have been strongly and habitually impressed with the
persuasion of a Divine Purpose and Power which had regulated the
events which they had attended to, and ordained the laws which they
had detected.
To those who have pursued science without reaching the rank of
discoverers;--who have possessed a derivative knowledge of the laws
of nature which others had disclosed, and have employed themselves
in tracing the consequences of such laws, and systematizing the
body of truth thus produced, the above description does not apply;
and we have not therefore in these cases the same ground for
anticipating the same frame of mind. If among men of science of
this class, the persuasion of a supreme Intelligence has at some
periods been less vivid and less universal, than in that higher
class of which we have before spoken, the fact, so far as it has
existed, may perhaps be in some degree accounted for. But whether
the view which we have to give of the mental peculiarities of men
whose science is of this derivative kind be well founded, and
whether the account we have above offered of that which takes
place in the minds of original discoverers of laws in scientific
researches be true, or not, it will probably be considered a matter
of some interest to point out historically that in fact, such
discoverers have been peculiarly in the habit of considering the
world as the work of God. This we shall now proceed to do.
As we have already said, the names of _great_ discoverers are
not very numerous. The sciences which we may look upon as having
reached or at least approached their complete and finished form,
are Mechanics, Hydrostatics, and Physical Astronomy. Galileo is
the father of modern Mechanics; Copernicus, Kepler, and Newton are
the great names which mark the progress of Astronomy. Hydrostatics
shared in a great measure the fortunes of the related science of
Mechanics; Boyle and Pascal were the persons mainly active in
developing its more peculiar principles. The other branches of
knowledge which belong to natural philosophy, as Chemistry and
Meteorology, are as yet imperfect, and perhaps infant sciences;
and it would be rash to presume to select, in them, names of equal
preeminence with those above mentioned: but it may not be difficult
to show, with sufficient evidence, that the effect of science upon
the authors of science is, in these subjects as in the former ones,
far other than to alienate their minds from religious trains of
thought, and a habit of considering the world as the work of God.
We shall not dwell much on the first of the above mentioned great
names, Galileo; for his scientific merit consisted rather in
adopting the sound philosophy of others, as in the case of the
Copernican system, and in combating prevalent errors, as in the
case of the Aristotelian doctrines concerning motion, than in
any marked and prominent discovery of new principles. Moreover
the mechanical laws which he had a share in bringing to light,
depending as they did, rather on detached experiments and transient
facts, than on observation of the general course of the universe,
could not so clearly suggest any reflection on the government of
the world at that period, as they did afterwards when Newton showed
their bearing on the cosmical system. Yet Galileo, as a man of
philosophical and inventive mind, who produced a great effect on
the progress of physical knowledge, is a person whose opinions must
naturally interest us, engaged in our present course of reasoning.
There is in his writings little which bears upon religious views,
as there is in the nature of his works little to lead him to such
subjects. Yet strong expressions of piety are not wanting, both
in his letters, and in his published treatises. The persecution
which he underwent, on account of his writings in favour of the
Copernican system, was grounded, not on his opposition to the
general truths of natural religion, which is our main concern at
present, nor even on any supposed rejection of any articles of
Christian faith, but on the alleged discrepancy between his adopted
astronomical views and the declarations of scripture. Some of his
remarks may interest the reader.
In his third dialogue on the Copernican system he has occasion
to speak of the opinion which holds all parts of the world to be
framed for man’s use alone: and to this he says, “I would that we
should not so shorten the arm of God in the government of human
affairs; but that we should rest in this, that we are certain
that God and nature are so occupied in the government of human
affairs, that they could not more attend to us if they were charged
with the care of the human race alone.” In the same spirit, when
some objected to the asserted smallness of the Medicean stars, or
satellites of Jupiter, and urged this as a reason why they were
unworthy the regard of philosophers, he replied that they are the
works of God’s power, the objects of His care, and therefore may
well be considered as sublime subjects for man’s study.
In the Dialogues on Mechanics, there occur those observations
concerning the use of the air-bladder in fishes, and concerning the
adaptation of the size of animals to the strength of the materials
of which they are framed, which have often since been adopted by
writers on the wisdom of Providence. The last of the dialogues on
the system of the world is closed by a religious reflection, put
in the mouth of the interlocutor who usually expresses Galileo’s
own opinions. “While it is permitted us to speculate concerning the
constitution of the world, we are also taught (perhaps in order
that the activity of the human mind may not pause or languish) that
our powers do not enable us to comprehend the works of His hands.
May success therefore attend this intellectual exercise, thus
permitted and appointed for us; by which we recognize and admire
the greatness of God the more, in proportion as we find ourselves
the less able to penetrate the profound abysses of his wisdom.”
And that this train of thought was habitual to the philosopher we
have abundant evidence in many other parts of his writings. He had
already said in the same dialogue, “Nature (or God, as he elsewhere
speaks) employs means in an admirable and inconceivable manner;
admirable, that is, and inconceivable to us, but not to her, who
brings about with consummate facility and simplicity things which
affect our intellect with infinite astonishment. That which is to
us most difficult to understand is to her most easy to execute.”
The establishment of the Copernican and Newtonian views of the
motions of the solar system and their causes, were probably the
occasions on which religious but unphilosophical men entertained
the strongest apprehensions that the belief in the government of
God may be weakened when we thus “thrust some mechanic cause into
his place.” It is therefore fortunate that we can show, not only
that this ought not to occur, from the reason of the thing, but
also that in fact the persons who are the leading characters in the
progress of these opinions were men of clear and fervent piety.
In the case of Copernicus himself it does not appear that,
originally, any apprehensions were entertained of any dangerous
discrepancy between his doctrines and the truths of religion,
either natural or revealed. The work which contains these memorable
discoveries was addressed to Pope Paul III., the head, at that
time, (1543) of the religious world; and was published, as the
author states in the preface, at the urgent entreaty of friends,
one of whom was a cardinal, and another a bishop.[33] “I know,”
he says, “that the thoughts of a philosopher are far removed from
the judgment of the vulgar; since it is his study to search out
truth in all things, as far as that is permitted by God to human
reason.” And though the doctrines are for the most part stated as
portions of a mathematical calculation, the explanation of the
arrangement by which the sun is placed in the centre of the system
is accompanied by a natural reflection of a religious cast; “Who in
this fair temple would place this lamp in any other or better place
than there whence it may illuminate the whole? We find then under
this ordination an admirable symmetry of the world, and a certain
harmonious connexion of the motion and magnitude of the orbs,
such as in any other way cannot be found. Thus the progressions
and regressions of the planets all arise from the same cause, the
motion of the earth. And that no such movements are seen in the
fixed stars, argues their immense distance from us, which causes
the apparent magnitude of the earth’s annual course to become
evanescent. So great, in short, is this divine fabric of the great
and good God;”[34] “this best and most regular artificer of the
universe,” as he elsewhere speaks.
Kepler was the person, who by further studying “the connexion of
the motions and magnitude of the orbs,” to which Copernicus had
thus drawn the attention of the astronomers, detected the laws of
this connexion, and prepared the way for the discovery, by Newton,
of the mechanical laws and causes of such motions. Kepler was
a man of strong and lively piety; and the exhortation which he
addresses to his reader before entering on the exposition of some
of his discoveries, may be quoted not only for its earnestness but
its reasonableness also. “I beseech my reader, that not unmindful
of the divine goodness bestowed on man, he do with me praise and
celebrate the wisdom and greatness of the Creator, which I open
to him from a more inward explication of the form of the world,
from a searching of causes, from a detection of the errors of
vision: and that thus, not only in the firmness and stability
of the earth he perceive with gratitude the preservation of all
living things in nature as the gift of God, but also that in its
motion, so recondite, so admirable, he acknowledge the wisdom of
the Creator. But him who is too dull to receive this science, or
too weak to believe the Copernican system without harm to his
piety, him, I say, I advise that, leaving the school of astronomy,
and condemning, if he please, any doctrines of the philosophers,
he follow his own path, and desist from this wandering through the
universe, and lifting up his natural eyes, with which alone he
can see, pour himself out from his own heart in praise of God the
Creator; being certain that he gives no less worship to God than
the astronomer, to whom God has given to see more clearly with his
inward eye, and who, for what he has himself discovered, both can
and will glorify God.”
The next great step in our knowledge of the universe, the discovery
of the mechanical causes by which its motions are produced, and
of their laws, has in modern times sometimes been supposed, both
by the friends of religion and by others, to be unfavourable
to the impression of an intelligent first cause. That such a
supposition is founded in error we have offered what appear to us
insurmountable reasons for believing. That in the mind of the great
discoverer of this mechanical cause, Newton, the impression of a
creating and presiding Deity was confirmed, not shaken, by all
his discoveries, is so well known that it is almost superfluous
to insist upon the fact. His views of the tendency of science
invested it with no dangers of this kind. “The business of
natural philosophy is,” he says, (Optics, Qu. 28,) “to argue from
phenomena without feigning hypotheses, and to deduce cause from
effects, till we come to the very first cause, which is certainly
not mechanical.” “Though every true step made in this philosophy
brings us not immediately to the knowledge of the first cause, yet
it brings us nearer to it, and is on that account highly to be
valued.” The Scholium, or note, which concludes his great work,
the Principia, is a well known and most striking evidence on this
point, “This beautiful system of sun, planets, and comets, could
have its origin in no other way than by the purpose and command of
an intelligent and powerful Being. He governs all things, not as
the soul of the world, but as the lord of the universe. He is not
only God, but Lord or Governor. We know him only by his properties
and attributes, by the wise and admirable structure of things
around us, and by their final causes; we admire him on account of
his perfections, we venerate and worship him on account of his
government.”
Without making any further quotations, it must be evident to
the reader that the succession of great philosophers through
whom mankind have been led to the knowledge of the greatest of
scientific truths, the law of universal gravitation, did, for
their parts, see the truths which they disclosed to men in such a
light that their religious feelings, their reference of the world
to an intelligent Creator and Preserver, their admiration of his
attributes, were exalted rather than impaired by the insight which
they obtained into the structure of the universe.
Having shown this with regard to the most perfect portion of human
knowledge, our knowledge of the motions of the solar system, we
shall adduce a few other passages, illustrating the prevalence
of the same fact in other departments of experimental science;
although, for reasons which have already been intimated, we
conceive that sciences of experiment do not conduct so obviously as
sciences of observation to the impression of a Divine Legislator of
the material world.
The science of Hydrostatics was constructed in a great measure by
the founders of the sister science of Mechanics. Of those who were
employed in experimentally establishing the principles peculiarly
belonging to the doctrine of fluids, Pascal and Boyle are two of
the most eminent names. That these two great philosophers were
not only religious, but both of them remarkable for their fervent
and pervading devotion, is too well known to be dwelt on. With
regard to Pascal, however, we ought not perhaps to pass over an
opinion of his, that the existence of God cannot be proved from the
external world. “I do not undertake to prove this,” says he, “not
only because I do not feel myself sufficiently strong to find in
nature that which shall convince obstinate atheists, but because
such knowledge without Jesus Christ is useless and steril.” It is
obvious that such a state of mind would prevent this writer from
encouraging or dwelling upon the grounds of natural religion; while
yet he himself is an example of that which we wish to illustrate,
that those who have obtained the furthest insight into nature,
have been in all ages firm believers in God. “Nature,” he says, in
another place, “has perfections in order to show that she is the
image of God, and defects in order to show that she is only his
image.”[35]
Boyle was not only a most pious man as well as a great philosopher,
but he exerted himself very often and earnestly in his writings
to show the bearing of his natural philosophy upon his views of
the Divine attributes, and of the government of the world. Many
of these dissertations convey trains of thought and reasoning
which have never been surpassed for their combination of judicious
sobriety in not pressing his arguments too far, with fervent
devotion in his conceptions of the Divine nature. As examples of
these merits, we might adduce almost any portion of his tracts on
these subjects; for instance, his “Inquiry into the Final Causes
of Natural Things;” his “Free Inquiry into the Vulgar Notion of
Nature;” his “Christian Virtuoso;” and his essay entitled “The High
Veneration Man’s Intellect owes to God.” It would be superfluous to
quote at any length from these works. We may observe, however, that
he notices that general fact which we are at present employed in
exemplifying, that “in almost all ages and countries the generality
of philosophers and contemplative men were persuaded of the
existence of a Deity from the consideration of the phenomena of the
universe; whose fabric and conduct they rationally concluded could
not justly be ascribed either to chance or to any other cause than
a Divine Being.” And in speaking of the religious uses of science,
he says: “Though I am willing to grant that some impressions of
God’s wisdom are so conspicuous that even a superficial philosopher
may thence infer that the author of such works must be a wise
agent; yet how wise an agent he has in these works expressed
himself to be, none but an experimental philosopher can well
discern. And ’tis not by a slight survey, but by a diligent and
skilful scrutiny, of the works of God, that a man must be, by a
rational and affective conviction, engaged to acknowledge that
the author of nature ‘is wonderful in counsel, and excellent in
working.’”
After the mechanical properties of fluids, the laws of the
operation of the chemical and physical properties of the elements
about us, offer themselves to our notice. The relations of heat
and of moisture in particular, which play so important a part, as
we have seen, in the economy of our world, have been the subject
of various researches; and they have led to views of the operation
of such agents, some of which we have endeavoured to present to
the reader, and to point out the remarkable arrangements by which
their beneficial operation is carried on. That the discoverers
of the laws by which such operations are regulated, were not
insensible to the persuasion of a Divine care and contrivance
which those arrangements suggest, is what we should expect, in
agreement with what we have already said, and it is what we find.
Among the names of the philosophers to whom we owe our knowledge
on these subjects, there are none greater than those of Black,
the discoverer of the laws of latent heat, and Dalton, who first
gave us a true view of the mode in which watery vapour exists and
operates in the atmosphere. With regard to the former of these
philosophers, we shall quote Dr. Thomson’s account of the views
which the laws of latent heat suggested to the discoverer.[36] “Dr.
Black quickly perceived the vast importance of this discovery,
and took a pleasure in laying before his students a view of
the beneficial effects of this habitude of heat in the economy
of nature. During the summer season a vast magazine of heat is
accumulated in the water, which by gradually emerging during
congelation serves to temper the cold of winter. Were it not for
this accumulation of heat in water and other bodies, the sun would
no sooner go a few degrees to the south of the equator than we
should feel all the horrors of winter.”
In the same spirit are Mr. Dalton’s reflections, after pointing
out the laws which regulate the balance of evaporation and
rain,[37] which he himself first clearly explained. “It is scarcely
possible,” says he, “to contemplate without admiration the
beautiful system of nature by which the surface of the earth is
continually supplied with water, and that unceasing circulation of
a fluid so essentially necessary to the very being of the animal
and vegetable kingdom takes place.”
Such impressions appear thus to rise irresistibly in the breasts
of men, when they obtain a sight, for the first time, of the
varied play and comprehensive connexions of the laws by which the
business of the material world is carried on and its occurrences
brought to pass. To dwell upon or develope such reflections is not
here our business. Their general prevalence in the minds of those
to whom these first views of new truths are granted, has been, we
trust, sufficiently illustrated. Nor are the names adduced above,
distinguished as they are, brought forwards as _authorities_
merely. We do not claim for the greatest discoverers in the realms
of science any immunity from error. In their general opinions they
may, as others may, judge or reason ill. The articles of their
religious belief may be as easily and as widely as of other men’s,
imperfect, perverted, unprofitable. But on this one point, the
tendency of our advances in scientific knowledge of the universe
to lead us up to a belief in a most wise maker and master of the
universe, we conceive that they who make these advances, and who
feel, as an original impression, that which others feel only
by receiving their teaching, must be looked to with a peculiar
attention and respect. And what their impressions have commonly
been, we have thus endeavoured to show.
CHAPTER VI.
_On Deductive Habits; or, on the Impression produced on Men’s
Minds by tracing the consequences of ascertained Laws._
The opinion illustrated in the last chapter, that the advances
which men make in science tend to impress upon them the reality of
the Divine government of the world, has often been controverted.
Complaints have been made, and especially of late years, that the
growth of piety has not always been commensurate with the growth
of knowledge, in the minds of those who make nature their study.
Views of an irreligious character have been entertained, it is
sometimes said, by persons eminently well instructed in all the
discoveries of modern times, no less than by the superficial and
ignorant. Those who have been supposed to deny or to doubt the
existence, the providence, the attributes of God, have in many
cases been men of considerable eminence and celebrity for their
attainments in science. The opinion that this is the case, appears
to be extensively diffused, and this persuasion has probably
often produced inquietude and grief in the breasts of pious and
benevolent men.
This opinion, concerning the want of religious convictions among
those who have made natural philosophy their leading pursuit,
has probably gone far beyond the limits of the real fact. But if
we allow that there are any strong cases to countenance such an
opinion, it may be worth our while to consider how far they admit
of any satisfactory explanation. The fact appears at first sight
to be at variance with the view we have given of the impression
produced by scientific discovery; and it is moreover always a
matter of uneasiness and regret, to have men of eminent talents
and knowledge opposed to doctrines which we consider as important
truths.
We conceive that an explanation of such cases, if they should
occur, may be found in a very curious and important circumstance
belonging to the process by which our physical sciences are formed.
The first discovery of new general truths, and the developement
of these truths when once obtained, are two operations extremely
different; imply different mental habits, and may easily be
associated with different views and convictions on points out of
the reach of scientific demonstration. There would therefore be
nothing surprising, or inconsistent with what we have maintained
above, if it should appear that while original discoverers of laws
of nature are peculiarly led, as we have seen, to believe the
existence of a supreme intelligence and purpose; the far greater
number of cultivators of science, whose employment it is to learn
from others these general laws, and to trace, combine, and apply
their consequences, should have no clearness of conviction or
security from error on this subject, beyond what belongs to persons
of any other class.
This will, perhaps, become somewhat more evident by considering
a little more closely the distinction of the two operations of
discovery and developement, of which we have spoken above, and the
tendency which the habitual prosecution of them may be expected to
produce in the thoughts and views of the student.
We have already endeavoured in some measure to describe that which
takes place when a new law of nature is discovered. A number of
facts in which, before, order and connexion did not appear at all,
or appeared by partial and contradictory glimpses, are brought
into a point of view in which order and connexion become their
essential character. It is seen that each fact is but a different
manifestation of the same principle; that each particular is that
which it is, in virtue of the same general truth. The inscription
is deciphered; the enigma is guessed; the principle is understood;
the truth is enunciated.
When this step is once made, it becomes possible to deduce from the
truth thus established, a train of consequences often in no small
degree long and complex. The process of making these inferences
may properly be described by the word Deduction, while the very
different process by which a new principle is collected from an
assemblage of facts, has been termed Induction; the truths so
obtained and their consequences constitute the results of the
Inductive Philosophy; which is frequently and rightly described
as a science which ascends from particular facts to general
principles, and then descends again from these general principles
to particular applications and exemplifications.
While the great and important labours by which science is really
advanced consist in the successive steps of the _inductive_ ascent
in the discovery of new laws perpetually more and more general; by
far the greater part of our books of physical science unavoidably
consists in _deductive_ reasoning, exhibiting the consequences
and applications of the laws which have been discovered; and the
greater part of writers upon science have their minds employed in
this process of deduction and application.
This is true of many of those who are considered, and justly,
as distinguished and profound philosophers. In the mechanical
philosophy, that science which applies the properties of matter
and the laws of motion to the explanation of the phenomena of
the world, this is peculiarly the case. The laws, when once
discovered, occupy little room in their statement, and when no
longer contested, are not felt to need a lengthened proof. But
their consequences require far more room and far more intellectual
labour. If we take, for example, the laws of motion and the law
of universal gravitation, we can express in a few lines, that
which, when developed, represents and explains an innumerable
mass of natural phenomena. But here the course of developement is
necessarily so long, the reasoning contains so many steps, the
considerations on which it rests are so minute and refined, the
complication of cases and of consequences is so vast, and even
the involution arising from the properties of space and number
so serious, that the most consummate subtlety, the most active
invention, the most tenacious power of inference, the widest spirit
of combination, must be tasked and tasked severely, in order to
solve the problems which belong to this portion of science. And
the persons who have been employed on these problems, and who
have brought to them the high and admirable qualities which such
an office requires, have justly excited in a very eminent degree
the admiration which mankind feel for great intellectual powers.
Their names occupy a distinguished place in literary history; and
probably there are no scientific reputations of the last century
higher, and none more merited, than those earned by the great
mathematicians who have laboured with such wonderful success in
unfolding the mechanism of the heavens; such for instance as
D’Alembert, Clairault, Euler, Lagrange, Laplace.
But it is still important to recollect, that the mental employments
of men, while they are occupied in this portion of the task of the
formation of science, are altogether different from that which
takes place in the mind of a discoverer, who, for the first time,
seizes the principle which connects phenomena before unexplained,
and thus adds another original truth to our knowledge of the
universe. In explaining, as the great mathematicians just mentioned
have done, the phenomena of the solar system by means of the law
of universal gravitation, the conclusions at which they arrived
were really included in the truth of the law itself, whatever skill
and sagacity it might require to develope and extricate them from
the general principle. But when Newton conceived and established
the law itself, he added to our knowledge something which was not
contained in any truth previously known, nor deducible from it by
any course of mere reasoning. And the same distinction, in all
other cases, obtains, between these processes which establish the
principles, generally few and simple, on which our sciences rest,
and those reasonings and calculations, founded on the principles
thus obtained, which constitute by far the larger portion of
the common treatises on the most complete of the sciences now
cultivated.
Since the difference is so great between the process of inductive
generalization of physical facts, and that of mathematical
deduction of consequences, it is not surprising that the two
processes should imply different mental powers and habits. However
rare the mathematical talent, in its highest excellence, may be,
it is far more common, if we are to judge from the history of
science, than the genius which divines the general laws of nature.
We have several good mathematicians in every age; we have few great
discoverers in the whole history of our species.
The distinction being thus clearly established between original
discovery and derivative speculation, between the ascent to
principles and the descent from them, we have further to observe,
that the habitual and exclusive prosecution of the latter process
may sometimes exercise an unfavourable effect on the mind of the
student, and may make him less fitted and ready to apprehend and
accept truths different from those with which his reasonings
are concerned. We conceive, for example, that a person labours
under gross error, who believes the phenomena of the world to be
altogether produced by mechanical causes, and who excludes from
his view all reference to an intelligent First Cause and Governor.
But we conceive that reasons may be shown which make it more
probable that error of such a kind should find a place in the mind
of a person of deductive, than of inductive habits;--of a mere
mathematician or logician, than of one who studies the facts of the
natural world and detects their laws.
The person whose mind is employed in reducing to law and order and
intelligible cause the complex facts of the material world, is
compelled to look beyond the present state of his knowledge, and
to turn his thoughts to the existence of principles higher than
those which he yet possesses. He has seen occasions when facts
that at first seemed incoherent and anomalous, were reduced to
rule and connexion; and when limited rules were discovered to be
included in some rule of superior generality. He knows that all
facts and appearances, all partial laws, however confused and
casual they at present seem, must still, in reality, have this
same kind of bearing and dependence;--must be bound together by
some undiscovered principle of order;--must proceed from some
cause working by most steady rules;--must be included in some
wide and fruitful general truth. He cannot therefore consider any
principles which he has already obtained, as the ultimate and
sufficient reason of that which he sees. There must be some higher
principle, some ulterior reason. The effort and struggle by which
he endeavours to extend his view, makes him feel that there is a
region of truth not included in his present physical knowledge; the
very imperfection of the light in which he works his way, suggests
to him that there must be a source of clearer illumination at a
distance from him.
We must allow that it is scarcely possible to describe in a manner
free from some vagueness and obscurity, the effect thus produced
upon the mind by the efforts which it makes to reduce natural
phenomena to general laws. But we trust it will still be allowed
that there is no difficulty in seeing clearly that a different
influence may result from this process, and from the process
of deductive reasoning which forms the main employment of the
mathematical cultivators and systematic expositors of physical
science in modern times. Such persons are not led by their pursuits
to any thing beyond the general principles, which form the basis
of their explanations and applications. They acquiesce in these;
they make these their ultimate grounds of truth; and they are
entirely employed in unfolding the particular truths which are
involved in the general truth. Their thoughts dwell little upon the
possibility of the laws of nature being other than we find them
to be, or on the reasons why they are not so; and still less on
those facts and phenomena which philosophers have not yet reduced
to any rule; which are lawless to us, though we know that, in
reality, they are governed by some principle of order and harmony.
On the contrary, by assuming perpetually the existing laws as
the basis of their reasoning, without question or doubt, and by
employing such language that these laws can be expressed in the
simplest and briefest form, they are led to think and believe as
if these laws were necessarily and inevitably what they are. Some
mathematicians indeed have maintained that the highest laws of
nature with which we are acquainted, the laws of motion and the
law of universal gravitation, are not only necessarily true, but
are even self-evident and certain _à priori_, like the truths of
geometry. And though the mathematical cultivator of the science of
mechanics may not adopt this as his speculative opinion, he may
still be so far influenced by the tendency from which it springs,
as to rest in the mechanical laws of the universe as ultimate and
all-sufficient principles, without seeing in them any evidence of
their having been selected and ordained, and thus without ascending
from the world to the thought of an Intelligent Ruler. He may thus
substitute for the Deity certain axioms and first principles, as
the cause of all. And the follower of Newton may run into the error
with which he is sometimes charged, of thrusting some mechanic
cause into the place of God, if he do not raise his views, as his
master did, to some higher cause, to some source of all forces,
laws, and principles.
When, therefore, we consider the mathematicians who are employed
in successfully applying the mechanical philosophy, as men well
deserving of honour from those who take an interest in the progress
of science, we do rightly; but it is still to be recollected, that
in doing this they are not carrying us to any higher point of view
in the knowledge of nature than we had attained before: they are
only unfolding the consequences, which were already virtually in
our possession, because they were implied in principles already
discovered:--they are adding to our knowledge of effects, but
not to our knowledge of causes:--they are not making any advance
in that progress of which Newton spoke, and in which he made so
vast a stride, in which “every step made brings us nearer to the
knowledge of the first cause, and is on that account highly to be
valued.” And as in this advance they have no peculiar privileges or
advantages, their errors of opinion concerning it, if they err, are
no more to be wondered at, than those of common men; and need as
little disturb or distress us, as if those who committed them had
confined themselves to the study of arithmetic or of geometry. If
we can console and tranquillize ourselves concerning the defective
or perverted views of religious truth entertained by any of our
fellow men, we need find no additional difficulty in doing so when
those who are mistaken are great mathematicians, who have added to
the riches and elegance of the mechanical philosophy. And if we
are seeking for extraneous grounds of trust and comfort on this
subject, we may find them in the reflection;--that, whatever may
be the opinions of those who assume the causes and laws of that
philosophy and reason from them, the views of those admirable and
ever-honoured men who first caught sight of these laws and causes,
impressed _them_ with the belief that this is “the fabric of a
great and good God;” that “it is man’s duty to pour out his soul in
praise of the Creator;” and that all this beautiful system must be
referred to “a first cause, which is certainly not mechanical.”
2. We may thus, with the greatest propriety, deny to the mechanical
philosophers and mathematicians of recent times any authority
with regard to their views of the administration of the universe;
we have no reason whatever to expect from their speculations any
help, when we attempt to ascend to the first cause and supreme
ruler of the universe. But we might perhaps go further, and assert
that they are in some respects less likely than men employed in
other pursuits, to make any clear advance towards such a subject
of speculation. Persons whose thoughts are thus entirely occupied
in deduction are apt to forget that this is, after all, only one
employment of the reason among more; only one mode of arriving
at truth, needing to have its deficiencies completed by another.
Deductive reasoners, those who cultivate science, of whatever
kind, by means of mathematical and logical processes alone, may
acquire an exaggerated feeling of the amount and value of their
labours. Such employments, from the clearness of the notions
involved in them, the irresistible concatenation of truths which
they unfold, the subtlety which they require, and their entire
success in that which they attempt, possess a peculiar fascination
for the intellect. Those who pursue such studies have generally
a contempt and impatience of the pretensions of all those other
portions of our knowledge, where from the nature of the case, or
the small progress hitherto made in their cultivation, a more
vague and loose kind of reasoning seems to be adopted. Now if this
feeling be carried so far as to make the reasoner suppose that
these mathematical and logical processes can lead him to all the
knowledge and all the certainty which we need, it is clearly a
delusive feeling. For it is confessed on all hands, that all which
mathematics or which logic can do, is to develope and extract
those truths, as conclusions, which were in reality involved in
the principles on which our reasonings proceeded.[38] And this
being allowed, we cannot but ask how we obtain these principles?
from what other source of knowledge we derive the original truths
which we thus pursue into detail? since it is manifest that such
principles cannot be derived from the proper stores of mathematics
or logic. These methods can generate no new truth; and all the
grounds and elements of the knowledge which, through them, we
can acquire, must necessarily come from some extraneous source.
It is certain, therefore, that the mathematician and the logician
must derive from some process different from their own, the
substance and material of all our knowledge, whether physical or
metaphysical, physiological or moral. This process, by which we
acquire our first principles, (without pretending here to analyse
it,) is obviously the general course of human experience, and the
natural exercise of the understanding; our intercourse with matter
and with men, and the consequent growth in our minds of convictions
and conceptions such as our reason can deal with, either by her
systematic or unsystematic methods of procedure. Supplies from this
vast and inexhaustible source of original truths are requisite, to
give any value whatever to the results of our deductive processes,
whether mathematical or logical; while on the other hand, there are
many branches of our knowledge, in which we possess a large share
of original and derivative convictions and truths, but where it is
nevertheless at present quite impossible to erect our knowledge
into a complete system;--to state our primary and independent
truths, and to show how on these all the rest depend by the rules
of art. If the mathematician is repelled from speculations on
morals or politics, on the beautiful or the right, because the
reasonings which they involve have not mathematical precision
and conclusiveness, he will remain destitute of much of the most
valuable knowledge which man can acquire. And if he attempts to
mend the matter by giving to treatises on morals, or politics, or
criticism, a form and a phraseology borrowed from the very few
tolerably complete physical sciences which exist, it will be found
that he is compelled to distort and damage the most important
truths, so as to deprive them of their true shape and import, in
order to force them into their places in his artificial system.
If therefore, as we have said, the mathematical philosopher dwells
in his own bright and pleasant land of deductive reasoning, till
he turns with disgust from all the speculations, necessarily less
clear and conclusive, in which his imagination, his practical
faculties, his moral sense, his capacity of religious hope and
belief, are to be called into action, he becomes, more than common
men, liable to miss the road to truths of extreme consequence.
This is so obvious, that charges are frequently brought against
the study of mathematics, as unfitting men for those occupations
which depend upon our common instinctive convictions and feelings,
upon the unsystematic exercise of the understanding with regard
to common relations and common occurrences. Bonaparte observed of
Laplace, when he was placed in a public office of considerable
importance, that he did not discharge it in so judicious and
clear sighted a manner as his high intellectual fame might lead
most persons to expect.[39] “He sought,” that great judge of
character said, “subtleties in every subject, and carried into
his official employments the spirit of the method of infinitely
small quantities,” by which the mathematician solves his more
abstruse problems. And the complaint that mathematical studies
make men insensible to moral evidence and to poetical beauties, is
so often repeated as to show that some opposition of tendency is
commonly perceived between that exercise of the intellect which
mathematics requires and those processes which go on in our minds
when moral character or imaginative beauty is the subject of our
contemplation.
Thus, while we acknowledge all the beauty and all the value of
the mathematical reasonings by which the consequences of our
general laws are deduced, we may yet consider it possible that
a philosopher, whose mind has been mainly employed, and his
intellectual habits determined, by this process of deduction, may
possess, in a feeble and imperfect degree only, some of those
faculties by which truth is attained, and especially those truths
which regard our relation to that mind, the origin of all law, the
source of first principles, which must be immeasurably elevated
above all derivative truths. It would, therefore, be far from
surprising, if there should be found, among the great authors
of the developements of the mechanical philosophy, some who had
refused to refer the phenomena of the universe to a supreme mind,
purpose, and will. And though this world be, to a believer in the
Being and government of God, a matter of sorrow and pain, it need
not excite more surprise than if the same were true of a person
of the most ordinary endowments, when it is recollected in what a
disproportionate manner the various faculties of such a philosopher
may have been cultivated. And our apprehensions of injury to
mankind from the influence of such examples will diminish, when
we consider, that those mathematicians whose minds have been less
partially exercised, the great discoverers of the truths which
others apply, the philosophers who have looked upwards as well as
downwards, to the unknown as well as to the known, to ulterior as
well as proximate principles, have never rested in this narrow
and barren doctrine; but have perpetually looked forwards, beyond
mere material laws and causes, to a First Cause of the moral and
material world, to which each advance in philosophy might bring
them nearer, though it must ever remain indefinitely beyond their
reach.
It scarcely needs, perhaps, to be noticed, that what we here
represent as the possible source of error is, not the perfection
of the mathematical habits of the mind, but the deficiency of the
habit of apprehending truth of other kinds;--not a clear insight
into the mathematical consequences of principles, but a want of
a clear view of the nature and foundation of principles;--not
the talent for generalizing geometrical or mechanical relations,
but the tendency to erect such relations into ultimate truths
and efficient causes. The most consummate mathematical skill may
accompany and be auxiliary to the most earnest piety, as it often
has been. And an entire command of the conceptions and processes
of mathematics is not only consistent with, but is the necessary
condition and principal instrument of every important step in the
discovery of physical principles. Newton was eminent above the
philosophers of his time, in no one talent so much as in the power
of mathematical deduction. When he had caught sight of the law of
universal gravitation, he traced it to its consequences with a
rapidity, a dexterity, a beauty of mathematical reasoning which no
other person could approach; so that on this account, if there had
been no other, the establishment of the general law was possible to
him alone. He still stands at the head of mathematicians as well
as of philosophical discoverers. But it never appeared to him,
as it may have appeared to some mathematicians who have employed
themselves on his discoveries, that the general law was an ultimate
and sufficient principle: that the point to which he had hung his
chain of deduction was the highest point in the universe. Lagrange,
a modern mathematician of transcendent genius, was in the habit
of saying, in his aspirations after future fame, that Newton was
fortunate in having had the system of the world for his problem,
since its theory could be discovered once only. But Newton himself
appears to have had no such persuasion that the problem he had
solved was unique and final: he laboured to reduce gravity to some
higher law, and the forces of other physical operations to an
analogy with those of gravity, and declared that all these were
but steps in our advance towards a first cause. Between us and
this first cause, the source of the universe and of its laws, we
cannot doubt that there intervene many successive steps of possible
discovery and generalization, not less wide and striking than the
discovery of universal gravitation: but it is still more certain
that no extent or success of physical investigation can carry us to
any point which is not at an immeasurable distance from an adequate
knowledge of Him.
CHAPTER VII.
_On Final Causes._
We have pointed out a great number of instances where the mode in
which the arrangements of nature produce their effect, suggests,
as we conceive, the belief that this effect is to be considered as
the _end_ and _purpose_ of these arrangements. The impression which
thus arises, of design and intention exercised in the formation of
the world, or of the reality of _Final Causes_, operates on men’s
minds so generally, and increases so constantly on every additional
examination of the phenomena of the universe, that we cannot but
suppose such a belief to have a deep and stable foundation. And we
conceive that in several of the comparatively few cases in which
such a belief has been rejected, the averseness to it has arisen
from the influence of some of the causes mentioned in the last
chapter; the exclusive pursuit, namely, of particular trains and
modes of reasoning, till the mind becomes less capable of forming
the conceptions and making the exertions which are requisite for
the apprehension of truths not included among its usual subjects of
thought.
1. This seems to be the case with those who maintain that purpose
and design cannot be _inferred_ or _deduced_ from the arrangements
which we see around us by any process of reasoning. We can reason
from effects to causes, say such writers, only in cases where we
know something of the nature of the cause. We can infer from the
works of men, the existence of design and purpose, because we
know, from past observation, what kind of works human design and
purpose can produce. But the universe, considered as the work of
God, cannot be compared with any corresponding work, or judged
of by any analogy with known examples. How then can we, in this
case, they ask, infer design and purpose in the artist of the
universe? On what principles, on what axioms, can we proceed, which
shall include this necessarily singular instance, and thus give
legitimacy and validity to our reasonings?
What has already been said on the subject of the two different
processes by which we obtain principles, and by which we reason
from them, will suggest the reply to these questions. When we
collect design and purpose from the arrangements of the universe,
we do not arrive at our conclusion by a train of deductive
reasoning, but by the conviction which such combinations as we
perceive immediately and directly impress upon the mind. “Design
must have had a designer.” But such a principle can be of no avail
to one whom the contemplation or the description of the world does
not impress with the perception of design. It is not, therefore, at
the end, but at the beginning of our syllogisms, not among remote
conclusions, but among original principles, that we must place the
truth, that such arrangements, manifestations, and proceedings
as we behold about us imply a Being endowed with consciousness,
design, and will, from whom they proceed.
This is inevitably the mode in which such a conviction is acquired;
and that it is so, we may the more readily believe, when we
consider that it is the case with the design and will which we
ascribe to man, no less than in that which we believe to exist in
God. At first sight we might perhaps be tempted to say, that we
infer design and purpose from the works of man in one case, because
we have known these attributes in other cases produce effects in
some measure similar. But to this we must reply, by asking how we
come to know the existence of human design and purpose _at first_,
and _at all_? What we see around us are certain appearances,
things, successions of events; how come we ever to ascribe to other
men the thought and will of which we are conscious ourselves? How
do we come to believe that there are other men? How are we led
to elevate, in our conceptions, some of the _objects_ which we
perceive into _persons_? No doubt their actions, their words induce
us to do this. We see that the manifestations which we observe must
be so understood, and not otherwise. We feel that such actions,
such events must be connected by consciousness and personality;
that the actions are not the actions of things, but of persons;
not necessary and without significance, like the falling of a
stone, but voluntary and with purpose like what we do ourselves.
But this is not a result of reasoning: we do not infer this from
any similar case which we have known; since we are now speaking of
the _first_ conception of a will and purpose different from our
own. In arriving at such knowledge, we are aided only by our own
consciousness of what thought, purpose, will, are: and possessing
this regulative principle, we so decipher and interpret the complex
appearances which surround us, that we receive irresistibly the
persuasion of the existence of other men, with thought and will
and purpose like our own. And just in the same manner, when we
examine attentively the adjustment of the parts of the human frame
to each other and to the elements, the relation of the properties
of the earth to those of its inhabitants, or of the physical to
the moral nature of man, the thought must arise and cling to our
perceptions, however little it be encouraged, that this system,
every where so full of wonderful combinations, suited to the
preservation, and well-being of living creatures, is also the
expression of the intention, wisdom, and goodness of a personal
creator and governor.
We conceive then that it is so far from being an unsatisfactory
or unphilosophical process by which we collect the existence of
a Deity from the works of creation, that the process corresponds
most closely with that on which rests the most steadfast of our
convictions, next to that of our own existence, the belief of
the existence of other human beings. If any one ever went so far
in scepticism as to doubt the existence of any other person than
himself, he might, so far as the argument from final causes is
concerned, reject the being of God as well as that of man; but,
without dwelling on the possibility of such fantasies, when we
consider how impossible it is for men in general not to attribute
personality, purpose, thought, will to each other, in virtue of
certain combinations of appearances and actions, we must deem them
most consistent and reasonable in attributing also personality and
purpose to God, in virtue of the whole assemblage of appearances
and actions which constitute the universe, full as it is of
combinations from which such a suggestion springs. The vividness,
the constancy of the belief of a wise and good Being, thus
governing the world, may be different in different men, according
to their habit of directing their thoughts to the subject; but such
a belief is undoubtedly capable of becoming lively and steadfast
in the highest degree. It has been entertained and cherished by
enlightened and well-regulated minds in all ages; and has been,
at least since the rise of Christianity, not only the belief, but
a pervading and ruling principle of action of many men, and of
whole communities. The idea may be rendered more faint by turning
the mind away from it, and perhaps by indulging too exclusively in
abstract and general speculations. It grows stronger by an actual
study of the details of the creation; and, as regards the practical
consequences of such a belief, by a habit of referring our actions
and hopes to such a Governor. In this way it is capable of becoming
as real and fixed an impression as that of a human friend and
master; and all that we can learn, by observing the course of men’s
feelings and actions, tends to convince us, that this belief of
the being and presence and government of God, leads to the most
elevated and beneficial frame of mind of which man is capable.
2. How natural and almost inevitable is this persuasion of the
reality of Final Causes and consequent belief in the personality
of the Deity, we may gather by observing how constantly it recurs
to the thoughts, even of those who, in consequence of such
peculiarities of mental discipline as have been described, have
repelled and resisted the impression.
Thus, Laplace, of whom we have already spoken, as one of the
greatest mathematicians of modern times, expresses his conviction
that the supposed evidence of final causes will disappear as our
knowledge advances, and that they only seem to exist in those cases
where our ignorance leaves room for such a mistake. “Let us run
over,” he says, “the history of the progress of the human mind and
its errors: we shall perpetually see final causes pushed away to
the bounds of its knowledge. These causes, which Newton removed
to the limits of the solar system, were not long ago conceived to
obtain in the atmosphere, and employed in explaining meteors: they
are, therefore, in the eyes of the philosopher nothing more than
the expression of the ignorance in which we are of the real causes.”
We may observe that we have endeavoured to give a very different,
and, as we believe, a far truer view of the effect which philosophy
has produced on our knowledge of final causes. We have shown, we
trust, that the notion of design and end is transferred by the
researches of science, not from the domain of our knowledge to that
of our ignorance, but merely from the region of facts to that of
laws. We hold that, in this form, final causes in the atmosphere
are still to be conceived to obtain, no less than in an earlier
state of meteorological knowledge; and that Newton was right, when
he believed that he had established their reality in the solar
system, not expelled them from it.
But our more peculiar business at present is to observe that
Laplace himself, in describing the arrangements by which the
stability of the solar system is secured, uses language which
shows how irresistibly these arrangements suggest an adaptation
to its preservation as an _end_. If in his expressions we were to
substitute the Deity for the abstraction “nature” which he employs,
his reflection would coincide with that which the most religious
philosopher would entertain. “It seems that ‘God’ has ordered
every thing in the heavens to ensure the duration of the planetary
system, by _views_ similar to those which He appears to us so
admirably to follow upon the earth, for the preservation of animals
and the perpetuity of species.[40] This consideration alone would
explain the disposition of the system, if it were not the business
of the geometer to go further.” It may be possible for the geometer
to go further; but he must be strangely blinded by his peculiar
pursuits, if, when he has discovered the mode in which these views
are answered, he supposes himself to have obtained a proof that
there are no views at all. It would be as if the savage, who had
marvelled at the steady working of the steam engine, should cease
to consider it a work of art, as soon as the self-regulating part
of the mechanism had been explained to him.
The unsuccessful struggle in which those persons engage, who
attempt to throw off the impression of design in the creation,
appears in an amusing manner through the simplicity of the ancient
Roman poet of this school. Lucretius maintains that the eye was not
made for seeing, nor the ear for hearing. But the terms in which he
recommends this doctrine show how hard he knew it to be for men to
entertain such an opinion. His advice is,--
Illud in his rebus vitium _vehementer_ et istum
Effugere errorem, vitareque _præmeditator_,
Lumina ne facias oculorum clara creata,
Prospicere ut possimus. iv. 823.
’Gainst their preposterous error guard thy mind
Who say each organ was for use design’d;
Think not the visual orbs, so clear, so bright,
Were furnish’d for the purposes of sight.
Undoubtedly the poet is so far right, that a most “vehement”
caution and vigilant “premeditation” are necessary to avoid the
“vice and error” of such a persuasion. The study of the adaptations
of the human frame is so convincing, that it carries the mind with
it, in spite of the resistance suggested by speculative systems.
Cabanis, a modern French physiological writer of great eminence,
may be selected as a proof of this. Both by the general character
of his own speculations, and by the tone of thinking prevalent
around him, the consideration of design in the works of nature was
abhorrent from his plan. Accordingly, he joins in repeating Bacon’s
unfavourable mention of final causes. Yet when he comes to speak
of the laws of reproduction of the human race, he appears to feel
himself compelled to admit the irresistible manner in which such
views force themselves on the mind. “I regard,” he says, “with the
great Bacon, the philosophy of final causes as barren; but I have
elsewhere acknowledged that it was very difficult for the most
cautious man (l’homme le plus reservé) never to have recourse to
them in his explanations.”[41]
3. It may be worth our while to consider for a moment the opinion
here referred to by Cabanis, of the propriety of excluding the
consideration of final causes from our natural philosophy. The
great authority of Bacon is usually adduced on this subject.
“The handling of final causes,” says he, “mixed with the rest
in physical inquiries, hath intercepted the severe and diligent
inquiry of all real and physical causes, and given men the occasion
to stay upon these satisfactory and specious causes, to the great
arrest and prejudice of farther discovery.”[42]
A moment’s attention will show how well this representation agrees
with that which we have urged, and how far it is from dissuading
the reference to final causes in reasonings like those on which
we are employed. Final causes are to be excluded _from physical
inquiry_; that is, we are not to assume that we know the objects
of the Creator’s design, and put this assumed purpose in the
place of a physical cause. We are not to think it a sufficient
account of the clouds that they are for watering the earth, (to
take Bacon’s examples,) or “that the solidness of the earth is
for the station and mansion of living creatures.” The physical
philosopher has it for his business to trace clouds to the laws of
evaporation and condensation; to determine the magnitude and mode
of action of the forces of cohesion and crystallization by which
the materials of the earth are made solid and firm. This he does,
making no use of the notion of final causes: and it is precisely
because he has thus established his theories independently of any
assumption of an end, that the end, when after all, it returns upon
him and cannot be evaded, becomes an irresistible evidence of an
intelligent legislator. He finds that the effects, of which the
use is obvious, are produced by most simple and comprehensive laws;
and when he has obtained this view, he is struck by the beauty of
the means, by the refined and skilful manner in which the useful
effects are brought about;--points different from those to which
his researches were directed. We have already seen, in the very
case of which we have been speaking, namely, the laws by which the
clouds are formed and distribute their showers over the earth, how
strongly those who have most closely and extensively examined the
arrangements there employed (as Howard, Dalton, and Black) have
been impressed with the harmony and beauty which these contrivances
manifest.
We may find a further assertion of this view of the proper use of
final causes in philosophy, by referring to the works of one of
the greatest of our philosophers, and one of the most pious of
our writers, Boyle, who has an Essay on this subject. “I am by
all means,” says he, “for encouraging the contemplation of the
celestial part of the world, and the shining globes that adorn it,
and especially the sun and moon, in order to raise our admiration
of the stupendous power and wisdom of him who was able to frame
such immense bodies; and notwithstanding their vast bulk and
scarce conceivable rapidity, keep them for so many ages constant
both to the lines and degrees of their motion, without interfering
with one another. And doubtless we ought to return thanks and
praises to the divine goodness for having so placed the sun and
moon, and determined the former, or else the earth, to move in
particular lines for the good of men and other animals; and how
disadvantageous it would have been to the inhabitants of the earth
if the luminaries had moved after a different manner. I dare not,
however, affirm that the sun, moon, and other celestial bodies
were made solely for the use of man: _much less presume to prove
one system of the world to be true and another false; because the
former is better fitted to the convenience of mankind, or the
other less suited, or perhaps altogether useless to that end_.”
This passage exhibits, we conceive, that combination of feelings
which ought to mark the character of the religious natural
philosopher; an earnest piety ready to draw nutriment from the
contemplation of established physical truths; joined with a
philosophical caution, which is not seduced by the anticipation
of such contemplations, to pervert the strict course of physical
inquiry.
It is precisely through this philosophical care and scrupulousness
that our views of final causes acquire their force and value as
aids to religion. The object of such views is not to lead us to
physical truth, but to connect such truth, obtained by its proper
processes and methods, with our views of God, the master of the
universe, through those laws and relations which are thus placed
beyond dispute.
Bacon’s comparison of final causes to the vestal virgins is one of
those poignant sayings, so frequent in his writings, which it is
not easy to forget. “Like them,” he says, “they are dedicated to
God, and are barren.” But to any one who reads his work it will
appear in what spirit this was meant. “Not because those final
causes are not true and worthy to be inquired, being kept within
their own province.” (Of the Advancement of Learning, b. ii. p.
142.) If he had had occasion to develope his simile, full of latent
meaning as his similes so often are, he would probably have said,
that to these final causes barrenness was no reproach, seeing they
ought to be, not the mothers but the daughters of our natural
sciences; and that they were barren, not by imperfection of their
nature but in order that they might be kept pure and undefiled, and
so fit ministers in the temple of God.
CHAPTER VIII.
_On the Physical Agency of the Deity._
1. We are not to expect that physical investigation can enable us
to conceive the manner in which God acts upon the members of the
universe. The question, “Canst thou by searching find out God?”
must silence the boastings of science as well as the repinings
of adversity. Indeed, science shows us, far more clearly than
the conceptions of every day reason, at what an immeasurable
distance we are from any faculty of conceiving _how_ the universe,
material and moral, is the work of the Deity. But with regard
to the material world, we can at least go so far as this;--we
can perceive that events are brought about, not by insulated
interpositions of divine power exerted in each particular case,
but by the establishment of general laws. This, which is the view
of the universe proper to science, whose office it is to search
out these laws, is also the view which, throughout this work, we
have endeavoured to keep present to the mind of the reader. We
have attempted to show that it combines itself most readily and
harmoniously with the doctrines of Natural Theology; that the
arguments for those doctrines are strengthened, the difficulties
which affect them removed, by keeping it steadily before us. We
conceive, therefore, that the religious philosopher will do well to
bear this conception in his mind. God is the author and governor of
the universe through the laws which he has given to its parts, the
properties which he has impressed upon its constituent elements;
these laws and properties are, as we have already said, the
instruments with which he works; the institution of such laws, the
selection of the quantities which they involve, their combination
and application, are the modes in which he exerts and manifests his
power, his wisdom, his goodness: through these attributes, thus
exercised, the Creator of all, shapes, moves, sustains, and guides
the visible creation.
This has been the view of the relation of the Deity to the universe
entertained by the most sagacious and comprehensive minds ever
since the true object of natural philosophy has been clearly and
steadily apprehended. The great writer who was the first to give
philosophers a distinct and commanding view of this object, thus
expresses himself in his “Confession of Faith:” “I believe--that
notwithstanding God hath rested and ceased from creating since the
first Sabbath, yet, nevertheless, he doth accomplish and fulfil his
divine will in all things, great and small, singular and general,
as fully and exactly by providence, as he could by miracle and
new creation, though his working be not immediate and direct, but
by compass; not violating nature, which is his own law upon the
creature.”
And one of our own time, whom we can no longer hesitate to place
among the worthiest disciples of the school of Bacon, conveys the
same thought in the following passage: “The Divine Author of the
universe cannot be supposed to have laid down particular laws,
enumerating all individual contingencies, which his materials
have understood and obey--this would be to attribute to him the
imperfections of human legislation;--but rather, by creating them
endued with certain fixed qualities and powers, he has impressed
them in their origin with the _spirit_, not the letter of his law,
and made all their subsequent combinations and relations inevitable
consequences of this first impression.”[43]
2. This, which thus appears to be the mode of the Deity’s operation
in the material world, requires some attention on our part in
order to understand it with proper clearness. One reason of this
is, that it is a mode of operation altogether different from that
in which we are able to make matter fulfil our designs. Man can
construct exquisite machines, can call in vast powers, can form
extensive combinations, in order to bring about results which he
has in view. But in all this he is only taking advantage of laws
of nature which already exist; he is applying to his use qualities
which matter already possesses. Nor can he by any effort do more.
He can establish no new law of nature which is not a result of the
existing ones. He can invest matter with no new properties which
are not modifications of its present attributes. His greatest
advances in skill and power are made when he calls to his aid
forces which before existed unemployed, or when he discovers so
much of the habits of some of the elements as to be able to bend
them to his purpose. He navigates the ocean by the assistance of
the winds which he cannot raise or still: and even if we suppose
him able to control the course of these, his yet unsubjugated
ministers, this could only be done by studying their characters, by
learning more thoroughly the laws of air and heat and moisture. He
cannot give the minutest portion of the atmosphere new relations,
a new course of expansion, new laws of motion. But the Divine
operations, on the other hand, include something much higher. They
take in the establishment of the laws of the elements, as well
as the combination of these laws and the determination of the
distribution and quantity of the materials on which they shall
produce their effect. We must conceive that the Supreme Power has
ordained that air shall be rarefied, and water turned into vapour,
by heat; no less than that he has combined air and water so as to
sprinkle the earth with showers, and determined the quantity of
heat and air and water, so that the showers shall be as beneficial
as they are.
We may and must, therefore, in our conceptions of the Divine
purpose and agency, go beyond the analogy of human contrivances. We
must conceive the Deity, not only as constructing the most refined
and vast machinery, with which, as we have already seen, the
universe is filled; but we must also imagine him as establishing
those properties by which such machinery is possible: as giving to
the materials of his structure the qualities by which the material
is fitted to its use. There is much to be found, in natural
objects, of the same kind of contrivance which is common to these
and to human inventions; there are mechanical devices, operations
of the atmospheric elements, chemical processes;--many such have
been pointed out, many more exist. But besides these cases of the
combination of means, which, we seem able to understand without
much difficulty, we are led to consider the Divine Being as the
_author of the laws_ of chemical, of physical, and of mechanical
action, and of such other laws as make matter what it is;--and
this is a view which no analogy of human inventions, no knowledge
of human powers, at all assists us to embody or understand.
Science, therefore, as we have said, while it discloses to us the
mode of instrumentality employed by the Deity, convinces us, more
effectually than ever, of the impossibility of conceiving God’s
actions by assimilating them to our own.
3. The laws of material nature, such as we have described them,
operate at all times, and in all places; affect every province of
the universe, and involve every relation of its parts. Wherever
these laws appear, we have a manifestation of the intelligence by
which they were established. But a law supposes an agent, and a
power; for it is the mode according to which the agent proceeds,
the order according to which the power acts. Without the presence
of such an agent, of such a power, conscious of the relations
on which the law depends, producing the effects which the law
prescribes, the law can have no efficacy, no existence. Hence we
infer that the intelligence by which the law is ordained, the
power by which it is put in action, must be present at all times
and in all places where the effects of the law occur; that thus the
knowledge and the agency of the Divine Being pervade every portion
of the universe, producing all action and passion, all permanence
and change. The laws of nature are the laws which he, in his
wisdom, prescribes to his own acts; his universal presence is the
necessary condition of any course of events, his universal agency
the only origin of any efficient force.
This view of the relation of the universe to God has been
entertained by many of the most eminent of those who have combined
the consideration of the material world with the contemplation of
God himself. It may therefore be of use to illustrate it by a few
quotations, and the more so, as we find this idea remarkably dwelt
upon in the works of that writer whose religious views must always
have a peculiar interest for the cultivators of physical science,
the great Newton.
Thus, in the observations on the nature of the Deity with which
he closes the “Opticks,” he declares the various portions of the
world, organic and inorganic, “can be the effect of nothing else
than the wisdom and skill of a powerful ever living Agent, who
being in all places, is more able by his will to move the bodies
within his boundless uniform _sensorium_, and thereby to form and
reform the parts of the universe, than we are by our will to move
the parts of our own bodies.” And in the Scholium at the end of
the “Principia,” he says, “God is one and the same God always and
every where. He is omnipresent, not by means of his _virtue_ alone,
but also by his _substance_, for virtue cannot subsist without
substance. In him all things are contained, and move, but without
mutual passion: God is not acted upon by the motions of bodies;
and they suffer no resistance from the omnipresence of God.” And
he refers to several passages confirmatory of this view, not only
in the Scriptures, but also in writers who hand down to us the
opinions of some of the most philosophical thinkers of the pagan
world. He does not disdain to quote the poets, and among the rest,
the verses of Virgil;
Principio cœlum ac terras camposque liquentes
Lucentemque globum lunæ, Titaniaque astra,
Spiritus intus alit, totamque infusa per artus
Mens agitat molem et magno se corpore miscet:
warning his reader, however, against the doctrine which such
expressions as these are sometimes understood to express. “All
these things he rules, not as _the soul of the world_, but as the
Lord of all.”
Clarke, the friend and disciple of Newton, is one of those who has
most strenuously put forwards the opinion of which we are speaking,
“All things which we commonly say are the effects of the natural
powers of matter and laws of motion, are indeed (if we will speak
strictly and properly,) the effects of God’s acting upon matter
continually and at every moment, either immediately by himself, or
mediately by some created intelligent being. Consequently there is
no such thing as the course of nature, or the power of nature,”
independent of the effects produced by the will of God.
Dugald Stewart has adopted and illustrated the same opinion, and
quotes with admiration the well-known passage of Pope, concerning
the Divine Agency, which
“Lives through all life, extends through all extent,
Spreads undivided, operates unspent.”
Mr. Stewart, with no less reasonableness than charity, asserts the
propriety of interpreting such passages according to the scope
and spirit of the reasonings with which they are connected;[44]
since, though by a captious reader they might be associated with
erroneous views of the Deity, a more favourable construction will
often see in them only the results of the necessary imperfection
of our language, when we dwell upon the omnipresence and universal
activity of God.
Finally, we may add that the same opinions still obtain the assent
of the best philosophers and divines of our time. Sir John Herschel
says, (Discourse on the Study of Natural Philosophy, p. 37.) “We
would no way be understood to deny the constant exercise of His
direct power in maintaining the system of nature; or the ultimate
emanation, of every energy which material agents exert, from his
immediate will, acting in conformity with his own laws.” And the
Bishop of London, in a note to his “Sermon on the duty of combining
religious instruction with intellectual culture,” observes, “the
student in natural philosophy will find rest from all those
perplexities which are occasioned by the obscurity of causation, in
the supposition, which although it was discredited by the patronage
of Malebranche and the Cartesians, has been adopted by Clarke and
Dugald Stewart, and which is by far the most simple and sublime
account of the matter; that all the events, which are continually
taking place in the different parts of the material universe, are
the _immediate_ effects of the divine agency.”
CHAPTER IX.
_On the Impression produced by considering the Nature and
Prospects of Science; or, on the Impossibility of the Progress of
our Knowledge ever enabling us to comprehend the Nature of the
Deity._
If we were to stop at the view presented in the last chapter,
it might be supposed that--by considering God as eternal and
omnipresent, conscious of all the relations, and of all the objects
of the universe, instituting laws founded on the contemplation
of these relations, and carrying these laws into effect by his
immediate energy,--we had attained to a conception, in some degree
definite, of the Deity, such as natural philosophy leads us to
conceive him. But by resting in this mode of conception, we should
overlook, or at least should disconnect from our philosophical
doctrines, all that most interests and affects us in the character
of the Creator and Preserver of the world;--namely, that he is the
lawgiver and judge of our actions; the proper object of our prayer
and adoration; the source from which we may hope for moral strength
here, and for the reward of our obedience and the elevation of our
nature in another state of existence.
We are very far from believing that our philosophy alone can give
us such assurance of these important truths as is requisite for
our guidance and support; but we think that even our physical
philosophy will point out to us the necessity of proceeding far
beyond that conception of God, which represents him merely as the
mind in which reside all the contrivance, law, and energy of the
material world. We believe that the view of the universe which
modern science has already opened to us, compared with the prospect
of what she has still to do in pursuing the path on which she has
just entered, will show us how immeasurably inadequate such a mode
of conception would be: and that if we take into our account, as
we must in reason do, all that of which we have knowledge and
consciousness, and of which we have as yet no systematic science,
we shall be led to a conviction that the Creator and Preserver
of the material world must also contain in him such properties
and attributes as imply his moral character, and as fall in most
consistently with all that we learn in any other way of his
providence and holiness, his justice and mercy.
1. The sciences which have at present acquired any considerable
degree of completeness, are those in which an extensive and
varied collection of phenomena, and their proximate causes, have
been reduced to a few simple general laws. Such are Astronomy
and Mechanics, and perhaps, so far as its physical conditions
are concerned, Optics. Other portions of human knowledge can
be considered as perfect sciences, in any strict sense of the
term, only when they have assumed this form; when the various
appearances which they involve are reduced to a few principles,
such as the laws of motion and the mechanical properties of the
luminiferous ether. If we could trace the endless varieties of
the forms of crystals, and the complicated results of chemical
composition, to some one comprehensive law necessarily pointing out
the crystalline form of any given chemical compound, Mineralogy
would become an exact science. As yet, however, we can scarcely
boast of the existence of any other such sciences than those which
we at first mentioned: and so far therefore as we attempt to give
definiteness to our conception of the Deity, by considering him
as the intelligent depositary and executor of laws of nature, we
can subordinate to such a mode of conception no portion of the
creation, save the mechanical movements of the universe, and the
propagation and properties of light.
2. And if we attempt to argue concerning the nature of the laws
and relations which govern those provinces of creation whither our
science has not yet reached, by applying some analogy borrowed from
cases where it has been successful, we have no chance of attaining
any except the most erroneous and worthless guesses. The history of
human speculations, as well as the nature of the objects of them,
shows how certainly this must happen. The great generalizations
which have been established in one department of our knowledge,
have been applied in vain to the purpose of throwing light on
the other portions which still continue in obscurity. When the
Newtonian philosophy had explained so many mechanical facts, by
the two great steps,--of resolving the action of a whole mass
into the actions of its minutest particles, and considering these
particles as centres of force,--attempts were naturally soon made
to apply the same mode of explanation to facts of other different
kinds. It was conceived that the whole of natural philosophy must
consist in investigating the laws of force by which particles of
different substances attracted and repelled, and thus produced
motions, or vibrations _to_ and _from_ the particles. Yet what were
the next great discoveries in physics? The action of a galvanic
wire upon a magnet; which is not to attract or repel it, but to
turn it to the _right_ and _left_; to produce motion, not to or
from, but _transverse_ to the line drawn to the acting particles;
and again, the undulatory theory of light, in which it appeared
that the undulations must not be longitudinal, as all philosophers,
following the analogy of all cases previously conceived, had,
at first, supposed them to be, but _transverse_ to the path of
the ray. Here, though the step from the known to the unknown was
comparatively small, when made conjecturally it was made in a
direction very wide of the truth. How impossible then must it be to
attain in this manner to any conception of a law which shall help
us to understand the whole government of the universe!
3. Still, however, in the laws of the luminiferous ether, and of
the other fluid, (if it be another fluid) by which galvanism and
magnetism are connected, we have something approaching nearly to
mechanical action, and, possibly, hereafter to be identified with
it. But we cannot turn to any other part of our physical knowledge,
without perceiving that the gulf which separates it from the exact
sciences is yet wider and more obscure. Who shall enunciate for
us, and in terms of what notions, the general law of _chemical_
composition and decomposition? sometimes indeed we give the name
of _attraction_ to the affinity by which we suppose the particles
of the various ingredients of bodies to be aggregated; but no one
can point out any common feature between this and the attractions
of which alone we know the exact effects. He who shall discover the
true general law of the forces by which elements form compounds,
will probably advance as far beyond the discoveries of Newton, as
Newton went beyond Aristotle. But who shall say in what direction
this vast flight shall be, and what new views it shall open to us
of the manner in which matter obeys the laws of the Creator?
4. But suppose this flight performed;--we are yet but at the outset
of the progress which must carry us towards Him. We have yet to
begin to learn all that we are to know concerning the ultimate laws
of organized bodies. What is the principle of _life_? What is the
rule of that action of which assimilation, secretion, developement,
are manifestations? and which appears to be farther removed from
mere chemistry than chemistry is from mechanics. And what again is
the new principle, as it seems to be, which is exhibited in the
_irritability_ of an animal nerve? the existence of a sense? How
different is this from all the preceding notions! No efforts can
avoid or conceal the vast but inscrutable chasm. Those theorists,
who have maintained most strenuously the possibility of tracing
the phenomena of animal life to the influence of physical agents,
have constantly been obliged to suppose a mode of agency altogether
different from any yet known in physics. Thus Lamarck, one of
the most noted of such speculators, in describing the course of
his researches, says, “I was soon persuaded that the _internal
sentiment_ constituted a power which it was necessary to take into
account.” And Bichat, another writer on the same subject, while
he declares his dissent from Stahl, and the earlier speculators,
who had referred every thing in the economy of life to a single
principle, which they called the _anima_, the _vital principle_,
and so forth, himself introduces several principles, or laws,
all utterly foreign to the region of physics; namely, _organic
sensibility_, _organic contractility_, _animal sensibility_,
_animal contractility_, and the like. Supposing such principles
really to exist, how far enlarged and changed must our views be
before we can conceive these properties, including the faculty of
perception, which they imply, to be produced by the will and power
of one supreme Being, acting by fixed laws. Yet without conceiving
this, we cannot conceive the agency of that Deity, who is
incessantly thus acting, in countless millions of forms and modes.
How strongly then does science represent God to us as
incomprehensible! his attributes as unfathomable! His power, his
wisdom, his goodness, appear in each of the provinces of nature
which are thus brought before us; and in each, the more we study
them, the more impressive, the more admirable do they appear.
When then we find these qualities manifested in each of so many
successive ways, and each manifestation rising above the preceding
by unknown degrees, and through a progression of unknown extent,
what other language can we use concerning such attributes than that
they are _infinite_? What mode of expression can the most cautious
philosophy suggest, other than that He, to whom we thus endeavour
to approach, is infinitely wise, powerful, and good?
5. But with sense and consciousness the history of living things
only begins. They have instincts, affections, passions, will. How
entirely lost and bewildered do we find ourselves when we endeavour
to conceive these faculties communicated by means of general laws!
Yet they are so communicated from God, and of such laws he is the
lawgiver. At what an immeasurable interval is he thus placed above
every thing which the creation of the inanimate world alone would
imply; and how far must he transcend all ideas founded on such
laws as we find there!
6. But we have still to go further and far higher. The world
of reason and of morality is a part of the same creation, as
the world of matter and of sense. The will of man is swayed by
rational motives; its workings are inevitably compared with a
rule of action; he has a conscience which speaks of right and
wrong. These are laws of man’s nature no less than the laws of his
material existence, or his animal impulses. Yet what entirely new
conceptions do they involve? How incapable of being resolved into,
or assimilated to, the results of mere matter, or mere sense! Moral
good and evil, merit and demerit, virtue and depravity, if ever
they are the subjects of strict science, must belong to a science
which views these things, not with reference to time or space,
or mechanical causation, not with reference to fluid or ether,
nervous irritability or corporeal feeling, but to their own proper
modes of conception; with reference to the relations with which
it is possible that these notions may be connected, and not to
relations suggested by other subjects of a completely extraneous
and heterogeneous nature. And according to such relations must the
laws of the moral world be apprehended, by any intelligence which
contemplates them at all.
There can be no wider interval in philosophy than the separation
which must exist between the laws of mechanical force and motion,
and the laws of free moral action. Yet the tendency of men to
assume, in the portions of human knowledge which are out of
their reach, a similarity of type to those with which they are
familiar, can leap over even this interval. Laplace has asserted
that “an intelligence which, at a given instant, should know all
the forces by which nature is urged, and the respective situation
of the beings of which nature is composed, if, moreover, it were
sufficiently comprehensive to subject these data to calculation,
would include in the same _formula_, the movements of the largest
bodies of the universe and those of the slightest atom. Nothing
would be uncertain to such an intelligence, and the future, no
less than the past, would be present to its eyes.” If we speak
merely of mechanical actions, this may, perhaps, be assumed to be
an admissible representation of the nature of their connexion in
the sight of the supreme intelligence. But to the rest of what
passes in the world, such language is altogether inapplicable. A
_formula_ is a brief mode of denoting a rule of calculating in
which numbers are to be used: and numerical measures are applicable
only to things of which the relation depend on time and space. By
such elements, in such a mode, how are we to estimate happiness
and virtue, thought and will? To speak of a formula with regard to
such things, would be to assume that their laws must needs take the
shape of those laws of the material world which our intellect most
fully comprehends. A more absurd and unphilosophical assumption we
can hardly imagine.
We conceive, therefore, that the laws by which God governs his
moral creatures, reside in his mind, invested with that kind of
generality, whatever it be, of which such laws are capable; but of
the character of such general laws, we know nothing more certainly
than this, that it must be altogether different from the character
of those laws which regulate the material world. The inevitable
necessity of such a total difference is suggested by the analogy of
all the knowledge which we possess and all the conceptions which we
can form. And, accordingly, no persons, except those whose minds
have been biassed by some peculiar habit or course of thought,
are likely to run into the confusion and perplexity which are
produced by assimilating too closely the government and direction
of voluntary agents to the production of trains of mechanical
and physical phenomena. In whatever manner voluntary and moral
agency depend upon the Supreme Being, it must be in some such way
that they still continue to bear the character of will, action,
and morality. And, though too exclusive an attention to material
phenomena may sometimes have made physical philosophers blind to
this manifest difference, it has been clearly seen and plainly
asserted by those who have taken the most comprehensive views of
the nature and tendency of science. “I believe,” says Bacon, in
his Confession of Faith, “that, at the first the soul of man was
not produced by heaven or earth, but was breathed immediately from
God; so that _the ways and proceedings of God with spirits are not
included in nature; that is in the laws of heaven and earth_; but
are reserved to the law of his secret will and grace; wherein God
worketh still, and resteth not from the work of redemption, as
he resteth from the work of creation; but continueth working to
the end of the world.” We may be permitted to observe here, that,
when Bacon has thus to speak of God’s dealings with his moral
creatures, he does not take his phraseology from those sciences
which can offer none but false and delusive analogies; but helps
out the inevitable scantiness of our human knowledge, by words
borrowed from a source more fitted to supply our imperfections.
Our natural speculations cannot carry us to the ideas of “grace”
and “redemption;” but in the wide blank which they leave, of all
that concerns our hopes of the Divine support and favour, the
inestimable knowledge which revelation, as we conceive, gives us,
finds ample room and appropriate place.
7. Yet even in the view of our moral constitution which natural
reason gives, we may trace laws that imply a personal relation to
our Creator. How can we avoid considering _that_ as a true view
of man’s being and place, without which, his best faculties are
never fully developed, his noblest energies never called out, his
highest point of perfection never reached? Without the thought of a
God over all, superintending our actions, approving our virtues,
transcending our highest conceptions of good, man would never rise
to those higher regions of moral excellence which we know him to
be capable of attaining. “To deny a God,” again says the great
philosopher, “destroys magnanimity and the raising of human nature;
for take an example of a dog, and mark what a generosity and
courage he will put on, when he finds himself maintained by a man;
who, to him, is instead of a God, or _melior natura_: which courage
is manifestly such, as that creature, without that confidence of
a better nature than his own, could never attain. So man, when he
resteth and assureth himself upon divine protection and favour,
gathereth a force and faith, which human nature could not obtain.
Therefore, as atheism is in all respects hateful, so in this, that
it depriveth human nature of the means to exalt itself above human
frailty.”[45]
Such a law, then, of reference to a Supremely Good Being, is
impressed upon our nature, as the condition and means of its
highest moral advancement. And strange indeed it would be if we
should suppose, that in a system where all besides indicates
purpose and design, this law should proceed from no such origin;
and no less inconceivable, that such a law, purposely impressed
upon man to purify and elevate his nature, should delude and
deceive him.
8. Nothing remains, therefore, but that the Creator, who, for
purposes that even we can see to be wise and good, has impressed
upon man this tendency to look to him for support, for advancement,
for such happiness as is reconcileable with holiness;--to believe
him to be the union of all perfection, the highest point of all
intellectual and moral excellence;--IS, in reality, such a guardian
and judge, such a good, and wise, and perfect Being, as we thus
irresistibly conceive him. It would indeed be extravagant to assert
that the imagination of the creature, itself the work of God, can
invent a higher point of goodness, of justice, of holiness, than
the Creator himself possesses: that the Eternal Mind, from whom our
notions of good and right are derived, is not himself directed by
the rules which these notions imply.
It is difficult to dwell steadily on such thoughts. But they will
at least serve to confirm the view which it was our object to
illustrate; namely, how incomparably the nature of God must be
elevated above any conceptions which our natural reason enables
us to form; and we have been led to these reflections, it will be
recollected, by following the clue of which science gave us the
beginning. The Divine Mind must be conceived by us as the seat of
those laws of nature which we have discovered. It must be no less
the seat of those laws which we have not yet discovered, though
these may and must be of a character far different from any thing
we can guess. The Supreme Intelligence must therefore contain the
laws, each according to their true dependence, of organic life, of
sense, of animal impulse, and must contain also the purpose and
intent for which these powers were put in play. But the Governing
Mind must comprehend also the laws of the responsible creatures
which the world contains, and must entertain the purposes for
which their responsible agency was given them. It must include
these laws and purposes, connected by means of the notions, which
responsibility implies, of desert and reward, of moral excellence
in various degrees, and of well-being as associated with right
doing. All the laws which govern the moral world are expressions
of the thought and intentions of our Supreme Ruler. All the
contrivances for moral no less than for physical good, for the
peace of mind, and other rewards of virtue, for the elevation and
purification of individual character, for the civilization and
refinement of states, their advancement in intellect and virtue,
for the diffusion of good, and the repression of evil; all the
blessings that wait on perseverance and energy in a good cause;
on unquenchable love of mankind, and unconquerable devotedness to
truth; on purity and self-denial; on faith, hope, and charity;--all
these things are indications of the character, will, and future
intentions of that God, of whom we have endeavoured to track the
footsteps upon earth, and to show his handiwork in the heavens.
“This God is our God, for ever and ever.” And if, in endeavouring
to trace the tendencies of the vast labyrinth of laws by which the
universe is governed, we are sometimes lost and bewildered, and
can scarce, or not at all, discern the line by which pain, and
sorrow, and vice fall in with a scheme directed to the strictest
right and greatest good, we yet find no room to faint or falter;
knowing that these are the darkest and most tangled recesses of our
knowledge; that into them science has as yet cast no ray of light;
that in them reason has as yet caught sight of no general law by
which we may securely hold: while, in those regions where we can
see clearly, where science has thrown her strongest illumination
upon the scheme of creation; where we have had displayed to us
the general laws which give rise to all multifarious variety of
particular facts;--we find all full wisdom, and harmony, and
beauty: and all this wise selection of means, this harmonious
combination of laws, this beautiful symmetry of relations,
directed, with no exception which human investigation has yet
discovered, to the preservation, the diffusion, the well-being
of those living things, which, though of their nature we know
so little, we cannot doubt to be the worthiest objects of the
Creator’s care.
FINIS.
FOOTNOTES:
[1] Loudon, Encyclopædia of Gardening, 848.
[2] Dec. Phys. vol. ii. 478.
[3] Fleming, Zool. i. 400.
[4] Rapports du Physique et du Moral de l’Homme, II. 371.
[5] It will be observed that it is not here asserted that the
difference of native products depends on the difference of climate
_alone_.
[6] The resemblance consists in this; that we have a strip of
greater temperature accompanied by a strip of smaller temperature,
these strips arising from the diurnal and nocturnal impressions
respectively, and being in motion; as in the waves on a canal, we
have a moving strip of greater elevation accompanied by a strip
of smaller elevation. We do not here refer to any hypothetical
undulations in the fluid matter of heat.
[7] Loudon, 1219.
[8] Loudon, 1214.
[9] Manchester Memoirs, v. 357.
[10] Howard on the climate of London, vol. ii. pp. 216, 217.
[11] Daniell, Meteor. Ess. p. 56.
[12] Daniell. p. 129.
[13] Phil. Trans. 1821.
[14] Mr. Gough in Manch. Mem. vol. v.
[15] The reader who is acquainted with the two theories of light,
will perceive that though we have adopted the doctrine of the
ether, the greater part of the arguments adduced would be equally
forcible, if expressed in the language of the theory of emission.
[16] Or rather through the _focal centre_ of the eye, which is
always near the centre of the pupil.
[17] Laplace, Expos. du Syst. du Monde, p. 441.
[18] In this statement of Laplace, however, one remarkable
provision for the stability of the system is not noticed.
The planets Mercury and Mars, which have much the largest
eccentricities among the old planets, are those of which the
masses are much the smallest. The mass of Jupiter is more than two
thousand times that of either of these planets. If the orbit of
Jupiter were as eccentric as that of Mercury is, all the security
for the stability of the system, which analysis has yet pointed
out, would disappear. The earth and the smaller planets might in
that case change their approximately circular orbits into very long
ellipses, and thus might fall into the sun, and fly off into remote
space.
It is further remarkable that in the newly discovered planets, of
which the orbits are still more eccentric than that of Mercury, the
masses are still smaller, so that the same provision is established
in this case also. It does not appear that any mathematician has
even attempted to point out a necessary connexion between the mass
of a planet and the eccentricity of its orbit on any hypothesis.
May we not then consider this combination of small masses with
large eccentricities, so important to the purposes of the world, as
a mark of provident care in the Creator?
[19] The _eccentricity_ of a planet’s orbit is measured by taking
the proportion of the _difference_ of the greatest and least
distances from the sun, to the _sum_ of the same distances.
Mercury’s greatest and least distances are as two and three; his
eccentricity, therefore, is one-fifth.
[20] The stability of the axis of rotation about which the earth
revolves, has sometimes been adduced as an instance of preservative
care. The stability, however, would follow necessarily, if the
earth, or its superficial parts, were originally fluid; and
that they were so is an opinion widely received, both among
astronomers and geologists. The original fluidity of the earth
is probably a circumstance depending upon the general scheme of
creation; and cannot with propriety be considered with reference
to one particular result. We shall therefore omit any further
consideration of this argument.
[21] Airy on Encke’s Comet, p. 1, note.
[22] Principia, b. iii. prop. x.
[23] Paley.
[24] If the Laws of Motion are stated as _three_, which we conceive
to be the true view of the subject, the other two, as applied in
mechanical reasonings, are the following:
_Second Law._ When a force acts on a body in motion, it produces
the same effect as if the same force acted on a body at rest.
_Third Law._ When a force of the nature of pressure produces
motion, the velocity produced is proportional to the force, other
things beings equal.
[25] Though Friction is not concerned in any cosmical phenomena, we
have thought this the proper place to introduce the consideration
of it; since the contrast between the cases in which it does act,
and those in which it does not, is best illustrated by a comparison
of cosmical with terrestrial motions.
[26] Butler, Serm. 3.
[27] Müller, Infusoria, Preface.
[28] _Monas._ Müller. Cuvier.
[29] _Volvox._
[30] _Vibrio._ Müller. Cuvier.
[31] Dupuis. Origine des Cultes.
[32] Herschel on the Study of Nat. Phil. Art. 28.
[33] Amici me cunctantem atque etiam reluctantem, retraxerunt,
inter quos primus fuit Nicolaus Schonbergius, Cardinalis
Capuanus, in omni genere literatum celebris; proximus ille
vir mei amantissimus Tidemannus Gisius, episcopus Culmensis,
sacrarum ut est et omnium bonarum literarum studiosissimus.--_De
Revolutionibus. Præf. ad Paulum III._
[34] Lib. i. cx.
[35] Pensées, Art. viii. 1.
[36] Thomson’s Hist. of Chemistry, vol. i. 321.
[37] Manch. Mem. vol. v. p. 346.
[38] “Since all reasoning may be resolved into syllogisms,
and since in a syllogism the premises do virtually assert the
conclusion, it follows at once, that no truth can be elicited by
any process of reasoning.”--_Whately’s Logic_, p. 223.
Mathematics is the _logic of quantity_, and to this science the
observation here quoted is strictly applicable.
[39] A l’intérieur le ministre Quinette fut remplacé par
Laplace, géomêtre du premier rang, mais qui ne tarda pas à
se montrer administrateur plus que médiocre: des son premier
travail les consuls s’aperçurent qu’ils s’étaient trompés:
Laplace ne saisissait aucune question sous son vrai point de
vue: il cherchait des subtilités partout, n’avait que des idées
problématiques, et portait enfin l’esprit des infiniment petits
dans l’administration.--_Mémoires écrits à Ste Hélène_, i. 3.
[40] Il semble que la nature ait tout disposé dans le ciel, pour
assurer la durée du systême planétaire, par des vues semblables
à celles qu’elle nous parait suivre si admirablement sur la
terre, pour la conservation des individus et la perpétuité des
espèces.--_Syst. du Monde_, p. 442.
[41] Rapports du Physique et du Moral de l’Homme, i. 299.
[42] De Augment. Sc. ii. 105.
[43] Herschel on the Study of Nat. Phil. Art. 28.
[44] Elem. of Phil. ii. p. 273.
[45] Bacon. Essay on Atheism.
TRANSCRIBER’S NOTE
Obvious typographical errors and punctuation errors have been
corrected after careful comparison with other occurrences within
the text and consultation of external sources.
Except for those changes noted below, all misspellings in the text,
and inconsistent or archaic usage, have been retained.
Pg 47: ‘a slendar stalk’ replaced by ‘a slender stalk’.
Pg 48: ‘animal motious’ replaced by ‘animal motions’.
Pg 54: ‘the raingage’ replaced by ‘the rain gauge’.
Pg 67: ‘by Fourrier, and’ replaced by ‘by Fourier, and’.
Pg 69: ‘would dimininish’ replaced by ‘would diminish’.
Pg 72: ‘is obvitated by’ replaced by ‘is obviated by’.
Pg 81: ‘than 1-100dth to’ replaced by ‘than 1-100th to’.
Pg 131: ‘are nealy circular’ replaced by ‘are nearly circular’.
Pg 139: ‘by one anomally’ replaced by ‘by one anomaly’.
Pg 153: ‘would loose its’ replaced by ‘would lose its’.
Pg 174: ‘a memoir entited’ replaced by ‘a memoir entitled’.
Pg 174: ‘volocity, in’ replaced by ‘velocity, in’.
Pg 178: ‘effects take take place’ replaced by ‘effects take place’.
Pg 196: ‘and and Director of’ replaced by ‘and Director of’.
Pg 200: ‘for for her young’ replaced by ‘for her young’.
Pg 205: ‘in his puposes’ replaced by ‘in his purposes’.
Pg 224: ‘thus irremoveably’ replaced by ‘thus irremovably’.
Pg 228: ‘of knowlege and’ replaced by ‘of knowledge and’.
Pg 259: ‘and no othewise’ replaced by ‘and not otherwise’.
*** End of this LibraryBlog Digital Book "Astronomy and General Physics Considered with Reference to Natural Theology" ***
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