and possibly also a second-hand, moving over the graduated dial. Why do
these hands move? and why are their relative motions such as they are
observed to be? These questions cannot be answered without opening the
watch, mastering its various parts, and ascertaining their relationship
to each other. When this is done, we find that the observed motion of
the hands follows of necessity from the inner mechanism of the watch,
when acted upon by the force invested in the spring.
The motion of the hands may be called a phenomenon of art, but the case
is similar with the phenomena of nature. These also have their inner
mechanism, and their store of force to set that mechanism going. The
ultimate problem of physical science is to reveal this mechanism, to
discern this store, and to show that from the combined action of both
the phenomena of which they constitute the basis must of necessity flow.
I thought that an attempt to give you even a brief and sketchy
illustration of the manner in which scientific thinkers regard this
problem would not be uninteresting to you on the present occasion;
more especially as it will give me occasion to say a word or two on
the tendencies and limits of modern science; to point out the region
which men of science claim as their own, and where it is mere waste
of time to oppose their advance, and also to define, if possible, the
bourne between this and that other region to which the questionings and
yearnings of the scientific intellect are directed in vain.
But here your tolerance will be needed. It was the American Emerson, I
think, who said that it is hardly possible to state any truth strongly
without apparent injustice to some other truth. Truth is often of a
dual character, taking the form of a magnet with two poles; and many
of the differences which agitate the thinking part of mankind are to
be traced to the exclusiveness with which partisan reasoners dwell
upon one half of the duality in forgetfulness of the other half. The
proper course appears to be to state both halves strongly, and allow
each its fair share in the formation of the resultant conviction. But
this waiting for the statement of the two sides of a question implies
patience. It implies a resolution to suppress indignation if the
statement of the one half should clash with our convictions, and to
repress equally undue elation if the half-statement should happen to
chime in with our views. It implies a determination to wait calmly for
the statement of the whole, before we pronounce judgment in the form of
either acquiescence or dissent.
This premised, and, I trust, accepted, let us enter upon our task.
There have been writers who affirmed that the pyramids of Egypt were
the productions of nature; and in his early youth Alexander von
Humboldt wrote a learned essay with the express object of refuting
this notion. We now regard the pyramids as the work of men’s hands,
aided probably by machinery of which no record remains. We picture to
ourselves the swarming workers toiling at those vast erections, lifting
the inert stones, and, guided by the volition, the skill, and possibly
at times by the whip of the architect, placing them in their proper
positions. The blocks in this case were moved and posited by a power
external to themselves, and the final form of the pyramid expressed the
thought of its human builder.
Let us pass from this illustration of constructive power to another of
a different kind. When a solution of common salt is slowly evaporated,
the water which holds the salt in solution disappears, but the salt
itself remains behind. At a certain stage of concentration the salt
can no longer retain the liquid form; its particles, or molecules,
as they are called, begin to deposit themselves as minute solids,
so minute, indeed, as to defy all microscopic power. As evaporation
continues solidification goes on, and we finally obtain, through the
clustering together of innumerable molecules, a finite crystalline mass
of a definite form. What is this form? It sometimes seems a mimicry
of the architecture of Egypt. We have little pyramids built by the
salt, terrace above terrace from base to apex, forming a series of
steps resembling those up which the Egyptian traveller is dragged by
his guides. The human mind is as little disposed to look unquestioning
at these pyramidal salt-crystals as to look at the pyramids of Egypt
without inquiring whence they came. How, then, are those salt-pyramids
built up?
Guided by analogy, you may, if you like, suppose that, swarming
among the constituent molecules of the salt, there is an invisible
population, guided and coerced by some invisible master, and placing
the atomic blocks in their positions. This, however, is not the
scientific idea, nor do I think your good sense will accept it as a
likely one. The scientific idea is that the molecules act upon each
other without the intervention of slave labour; that they attract each
other and repel each other at certain definite points, or poles, and in
certain definite directions; and that the pyramidal form is the result
of this play of attraction and repulsion. While, then, the blocks of
Egypt were laid down by a power external to themselves, these molecular
blocks of salt are self-posited, being fixed in their places by the
forces with which they act upon each other.
I take common salt as an illustration because it is so familiar to
us all; but any other crystalline substance would answer my purpose
equally well. Everywhere, in fact, throughout inorganic nature, we have
this formative power, as Fichte would call it--this structural energy
ready to come into play, and build the ultimate particles of matter
into definite shapes. The ice of our winters and of our polar regions
is its handywork, and so equally are the quartz, felspar, and mica of
our rocks. Our chalk-beds are for the most part composed of minute
shells, which are also the product of structural energy; but behind the
shell, as a whole, lies a more remote and subtle formative act. These
shells are built up of little crystals of calc-spar, and to form these
crystals the structural force had to deal with the intangible molecules
of carbonate of lime. This tendency on the part of matter to organize
itself, to grow into shape, to assume definite forms in obedience to
the definite action of force, is, as I have said, all-pervading. It is
in the ground on which you tread, in the water you drink, in the air
you breathe. Incipient life, as it were, manifests itself throughout
the whole of what we call inorganic nature.
The forms of the minerals resulting from this play of polar forces are
various, and exhibit different degrees of complexity. Men of science
avail themselves of all possible means of exploring their molecular
architecture. For this purpose they employ in turn as agents of
exploration, light, heat, magnetism, electricity, and sound. Polarized
light is especially useful and powerful here. A beam of such light,
when sent in among the molecules of a crystal, is acted on by them, and
from this action we infer with more or less of clearness the manner
in which the molecules are arranged. That differences, for example,
exist between the inner structure of rock salt and crystallized sugar
or sugar-candy, is thus strikingly revealed. These differences may be
made to display themselves in chromatic phenomena of great splendour,
the play of molecular force being so regulated as to remove some of
the coloured constituents of white light, and to leave others with
increased intensity behind.
And now let us pass from what we are accustomed to regard as a dead
mineral to a living grain of corn. When it is examined by polarized
light, chromatic phenomena similar to those noticed in crystals are
observed. And why? Because the architecture of the grain resembles the
architecture of the crystal. In the grain also the molecules are set in
definite positions, and in accordance with their arrangement they act
upon the light. But what has built together the molecules of the corn?
I have already said regarding crystalline architecture that you may, if
you please, consider the atoms and molecules to be placed in position
by a power external to themselves. The same hypothesis is open to you
now. But if in the case of crystals you have rejected this notion of
an external architect, I think you are bound to reject it now, and to
conclude that the molecules of the corn are self-posited by the forces
with which they act upon each other. It would be poor philosophy to
invoke an external agent in the one case and to reject it in the other.
Instead of cutting our grain of corn into slices and subjecting it to
the action of polarized light, let us place it in the earth and subject
it to a certain degree of warmth. In other words, let the molecules,
both of the corn and of the surrounding earth, be kept in that state
of agitation which we call warmth. Under these circumstances, the
grain and the substances which surround it interact, and a definite
molecular architecture is the result. A bud is formed; this bud reaches
the surface, where it is exposed to the sun’s rays, which are also to
be regarded as a kind of vibratory motion. And as the motion of common
heat with which the grain and the substances surrounding it were first
endowed, enabled the grain and these substances to exercise their
attractions and repulsions, and thus to coalesce in definite forms,
so the specific motion of the sun’s rays now enables the green bud to
feed upon the carbonic acid and the aqueous vapour of the air. The bud
appropriates those constituents of both for which it has an elective
attraction, and permits the other constituent to resume its place in
the air. Thus the architecture is carried on. Forces are active at the
root, forces are active in the blade, the matter of the earth and the
matter of the atmosphere are drawn towards both, and the plant augments
in size. We have in succession, the bud, the stalk, the ear, the full
corn in the ear; the cycle of molecular action being completed by the
production of grains similar to that with which the process began.
Now there is nothing in this process which necessarily eludes the
conceptive or imagining power of the purely human mind. An intellect
the same in kind as our own would, if only sufficiently expanded, be
able to follow the whole process from beginning to end. It would see
every molecule placed in its position by the specific attractions and
repulsions exerted between it and other molecules, the whole process
and its consummation being an instance of the play of molecular force.
Given the grain and its environment, the purely human intellect might,
if sufficiently expanded, trace out _à priori_ every step of
the process of growth, and by the application of purely mechanical
principles demonstrate that the cycle must end, as it is seen to end,
in the reproduction of forms like that with which it began. A similar
necessity rules here to that which rules the planets in their circuits
round the sun.
You will notice that I am stating my truth strongly, as at the
beginning we agreed it should be stated. But I must go still further,
and affirm that in the eye of science _the animal body_ is just
as much the product of molecular force as the stalk and ear of corn,
or as the crystal of salt or sugar. Many of the parts of the body are
obviously mechanical. Take the human heart, for example, with its
system of valves, or take the exquisite mechanism of the eye or hand.
Animal heat, moreover, is the same in kind as the heat of a fire,
being produced by the same chemical process. Animal motion, too, is
as directly derived from the food of the animal, as the motion of
Trevethyck’s walking-engine from the fuel in its furnace. As regards
matter, the animal body creates nothing; as regards force, it creates
nothing. Which of you by taking thought can add one cubit to his
stature? All that has been said, then, regarding the plant may be
restated with regard to the animal. Every particle that enters into
the composition of a muscle, a nerve, or a bone, has been placed in
its position by molecular force. And unless the existence of law in
these matters be denied, and the element of caprice introduced, we
must conclude that, given the relation of any molecule of the body
to its environment, its position in the body might be determined
mathematically. Our difficulty is not with the _quality_ of the
problem, but with its _complexity_; and this difficulty might be
met by the simple expansion of the faculties which we now possess.
Given this expansion, with the necessary molecular data, and the chick
might be deduced as rigorously and as logically from the egg as the
existence of Neptune was deduced from the disturbances of Uranus, or as
conical refraction was deduced from the undulatory theory of light.
You see I am not mincing matters, but avowing nakedly what many
scientific thinkers more or less distinctly believe. The formation of
a crystal, a plant, or an animal, is in their eyes a purely mechanical
problem, which differs from the problems of ordinary mechanics in the
smallness of the masses and the complexity of the processes involved.
Here you have one half of our dual truth; let us now glance at the
other half. Associated with this wonderful mechanism of the animal
body we have phenomena no less certain than those of physics, but
between which and the mechanism we discern no necessary connexion. A
man, for example, can say _I feel, I think, I love_; but how does
_consciousness_ infuse itself into the problem? The human brain
is said to be the organ of thought and feeling; when we are hurt the
brain feels it, when we ponder it is the brain that thinks, when our
passions or affections are excited it is through the instrumentality of
the brain. Let us endeavour to be a little more precise here. I hardly
imagine there exists a profound scientific thinker, who has reflected
upon the subject, unwilling to admit the extreme probability of the
hypothesis, that for every fact of consciousness, whether in the domain
of sense, of thought, or of emotion, a certain definite molecular
condition is set up in the brain; who does not hold this relation of
physics to consciousness to be invariable, so that, given the state
of the brain, the corresponding thought or feeling might be inferred;
or given the thought or feeling, the corresponding state of the brain
might be inferred.
But how inferred? It is at bottom not a case of logical inference
at all, but of empirical association. You may reply that many of
the inferences of science are of this character; the inference, for
example, that an electric current of a given direction will deflect a
magnetic needle in a definite way; but the cases differ in this, that
the passage from the current to the needle, if not demonstrable, is
thinkable, and that we entertain no doubt as to the final mechanical
solution of the problem. But the passage from the physics of the
brain to the corresponding facts of consciousness is unthinkable.
Granted that a definite thought, and a definite molecular action in
the brain occur simultaneously; we do not possess the intellectual
organ, nor apparently any rudiment of the organ, which would enable us
to pass, by a process of reasoning, from the one to the other. They
appear together, but we do not know why. Were our minds and senses so
expanded, strengthened, and illuminated as to enable us to see and
feel the very molecules of the brain; were we capable of following all
their motions, all their groupings, all their electric discharges, if
such there be; and were we intimately acquainted with the corresponding
states of thought and feeling, we should be as far as ever from the
solution of the problem. ‘How are these physical processes connected
with the facts of consciousness?’ The chasm between the two classes
of phenomena would still remain intellectually impassable. Let the
consciousness of _love_, for example, be associated with a
right-handed spiral motion of the molecules of the brain, and the
consciousness of _hate_ with a left-handed spiral motion. We
should then know when we love that the motion is in one direction, and
when we hate that the motion is in the other; but the ‘WHY?’
would remain as unanswerable as before.
In affirming that the growth of the body is mechanical, and that
thought, as exercised by us, has its correlative in the physics of
the brain, I think the position of the ‘Materialist’ is stated, as
far as that position is a tenable one. I think the materialist will
be able finally to maintain this position against all attacks; but
I do not think, in the present condition of the human mind, that he
can pass beyond this position. I do not think he is entitled to say
that his molecular groupings and his molecular motions _explain_
everything. In reality they explain nothing. The utmost he can affirm
is the association of two classes of phenomena, of whose real bond
of union he is in absolute ignorance. The problem of the connexion
of body and soul is as insoluble in its modern form as it was in the
prescientific ages. Phosphorus is known to enter into the composition
of the human brain, and a trenchant German writer has exclaimed, ‘Ohne
Phosphor, kein Gedanke.’ That may or may not be the case; but even
if we knew it to be the case, the knowledge would not lighten our
darkness. On both sides of the zone here assigned to the materialist he
is equally helpless. If you ask him whence is this ‘Matter’ of which
we have been discoursing, who or what divided it into molecules, who
or what impressed upon them this necessity of running into organic
forms, he has no answer. Science is mute in reply to these questions.
But if the materialist is confounded and science rendered dumb, who
else is prepared with a solution? To whom has this arm of the Lord
been revealed? Let us lower our heads and acknowledge our ignorance,
priest and philosopher, one and all. Perhaps the mystery may resolve
itself into knowledge at some future day. The process of things upon
this earth has been one of amelioration. It is a long way from the
Iguanodon and his contemporaries to the President and Members of the
British Association. And whether we regard the improvement from the
scientific or from the theological point of view, as the result of
progressive development, or as the result of successive exhibitions of
creative energy, neither view entitles us to assume that man’s present
faculties end the series,--that the process of amelioration stops at
him. A time may therefore come when this ultra-scientific region by
which we are now enfolded may offer itself to terrestrial, if not to
human investigation. Two-thirds of the rays emitted by the sun fail to
arouse in the eye the sense of vision. The rays exist, but the visual
organ requisite for their translation into light does not exist. And
so from this region of darkness and mystery which surrounds us, rays
may now be darting which require but the development of the proper
intellectual organs to translate them into knowledge as far surpassing
ours as ours surpasses that of the wallowing reptiles which once held
possession of this planet. Meanwhile the mystery is not without its
uses. It certainly may be made a power in the human soul; but it is
a power which has feeling, not knowledge, for its base. It may be,
and will be, and we hope is turned to account, both in steadying and
strengthening the intellect, and in rescuing man from that littleness
to which, in the struggle for existence, or for precedence in the
world, he is continually prone.
EARLIER THOUGHTS.[8]
A WORK recently published by Mr. Murray contains a sketch of the
grounds on which the most advanced scientific thinkers of the present
day base their convictions as to the physical character of Light and
Heat. The fundamental idea there developed is, that the phenomena of
light and heat, like those of sound, are essentially _mechanical_.
Precisely the same reasoning applies to the vibrating ether which
produces the one as to the vibrating air which produces the other, and
both are dealt with substantially as we should deal with the waves of
a liquid or the swing of a pendulum. Reflection on this subject has
suggested the thought that the considerations brought forward in the
sketch referred to may apply themselves to certain phenomena which are
usually considered to lie outside the pale of physics, and thus may
indicate new relationships between man regarded as a being of intellect
and emotion, and the wondrous material system in the midst of which he
dwells.
All our intercourse with the external world consists exclusively in an
interchange of motion. From a vibrating, sonorous body, for example,
pulses are sent to the ear and stir the auditory nerve to motion. From
a luminous body pulses are sent to the eye, and stir the optic nerve to
motion. Other pulses of different periods strike upon other nerves,
and produce the sensation of heat; but, in all cases, whether it be
light, or sound, or ordinary feeling, the excitement of the nerves,
regarded more strictly, is the excitement of motion. And if the motion
be induced by internal causes instead of external, is it not fair
to infer that the effect on consciousness will be the same? Let any
nerve, for example, be thrown by morbid action into the precise state
of motion which would be communicated to it by the pulses of a heated
body, surely that nerve will declare itself hot--the mind will accept
the subjective intimation exactly as if it were objective. The retina,
as is well known, may be excited by purely mechanical means. A blow
on the eye will cause a luminous flash, and the mere pressure of the
finger on the external ball will produce a star of light, which Newton
compared to the circles on a peacock’s tail. Disease makes people see
visions and dream dreams; but, in all such cases, could we examine the
organs implicated, we should, on philosophical grounds, expect to find
them in that precise molecular condition which the real objects, if
present, would superinduce.
The colour of light is determined by the frequency of the ethereal
vibrations, as the pitch of sound is determined by the frequency of
the aërial ones. The red or purple, for example, of a British maiden’s
cheek and lips, the blue, violet, or brown of her eyes, have their
strict physical equivalents in the lengths of the waves which issue
from them; and these waves are not only as truly mechanical as the
waves of the sea, but they are capable of having their mechanical
value expressed in numbers. In the work already referred to, a chapter
is devoted to the relation which subsists between light and heat and
mere mechanical work. In virtue of this relation we can tell the
precise amount of work which a given amount of sunshine can perform.
Now, the hue of the cheek is caused by the extinction of certain of
the solar rays by the colouring matter of the cheek, the residual
colour being that seen. Could we interpose the substance to which some
English cheeks owe their bloom in the path of a beam passing through
a prism, we should probably find the orange and yellow and green of
the prismatic spectrum more or less absorbed, the red and a portion
of the blue being transmitted. This would give us a purplish blush
resembling that of the permanganate of potash, commonly called the
mineral chameleon, a solution of which acts upon the spectrum in the
manner just described. Inasmuch, then, as we can calculate with perfect
exactness the mechanical value of the total light which falls upon the
epidermis, a certain fraction of this will express the mechanical value
of the cheek’s colour. We do not therefore jest, but speak the words of
truth and soberness when we affirm that the rays to which the tinting
of any given cheek is due would, if mechanically applied, be competent
to move a wheelbarrow through a certain space, or to lift a scuttle of
coals to a certain calculable elevation.