research, physical science has of late years assumed a momentous
position in the world. Both in a material and in an intellectual
point of view it has produced, and it is destined to produce,
immense changes, vast social ameliorations, and vast alterations in
the popular conception of the origin, rule, and governance of
things. Miracles are wrought by science in the physical world, while
philosophy is forsaking its ancient metaphysical channels, and
pursuing those opened or indicated by scientific research. This must
become more and more the case as philosophic writers become more
deeply imbued with the methods of science, better acquainted with
the facts which scientific men have won, and with the great theories
which they have elaborated.
If you look at the face of a watch, you see the hour and
minute-hands, 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.
This 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 injury to some other truth. Under the
circumstances, the proper course appears to be to state both truths
strongly, and allow each its fair share, in the formation of the
resultant conviction. For 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 different parties affirm one half of the
duality in forgetfulness of the other half. 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 not to suffer
ourselves to be unduly elated if the half-statement should chime in
with our views. It implies a determination to wait calmly for the
statement of the whole before we pronounce judgment either in the
form of acquiescence or dissent.
This premised, 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 an 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 the stones in their proper positions.
The blocks in this case were moved 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 building 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 mass of salt
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 thus a series
of steps resembling those up which the Egyptian traveler is dragged
by his guides. The human mind is as little disposed to look at these
pyramidal salt-crystals without further question 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 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 labor; that they attract each
other and repel each other at certain definite points, 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 almost any other substance would answer my purpose
equally well. 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. It is present everywhere. The ice of our
winters and of our polar regions is its hand-work, and so equally
are the quartz, feldspar, 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
the result of another and more subtle formative act. These shells
are built up of little crystals of calc-spar, and to form these 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, in fact, manifests itself
throughout the whole of what we call inorganic nature.
The forms of minerals resulting from this play of forces are
various, and exhibit different degrees of complexity. Men of science
avail themselves of all possible means of exploring this 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. The
difference, for example, between the inner structure of a plate of
rock-salt and a plate of crystalized sugar or sugar-candy is thus
strikingly revealed. These differences may be made to display
themselves in phenomena of color of great splendor, the play of
molecular force being so regulated as to remove certain of the
colored 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
in some degree the architecture of the crystal. In the corn the
molecules are also set in definite positions, from which 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 into thin 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
a state of agitation; for warmth, as most of you know, is, in the
eye of science, tremulous molecular motion. Under these
circumstances, the grain and the substances which surround it
interact, and a molecular architecture is the result of this
interaction. 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 common motion of heat with
which the grain and the substances surrounding it were first
endowed, enable the grain and these substances to coalesce, so the
specific motion of the sun’s rays now enables the green bud to feed
upon the carbonic acid and the aqueous vapor of the air,
appropriating those constituents of both for which the blade has an
elective attraction, and permitting the other constituent to resume
its place in the air. Thus 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 the plant, and the plant augments in
size. We have in succession, the bud, the stalk, the ear, the full
corn in the ear. For the forces here at play act in a cycle, which
is 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
power of mind as we know it. An intellect the same kind as our own,
would, if only sufficiently expanded, be able to follow the whole
process from beginning to end. No entirely new intellectual faculty
would be needed for this purpose. The duly expanded mind would see
in the process and its consummation an instance of the play of
molecular force. It would see every molecule placed in its position
by the specific attractions and repulsions exerted between it and
other molecules. Nay, given the grain and its environment, an
intellect the same in kind as our own, but sufficiently expanded,
might trace out _à priori_ every step of the process, and by the
application of mechanical principles would be able to demonstrate
that the cycle of actions must end, as it is seen to end, in the
reproduction of forms like that with which the operation 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 its parts are
obviously mechanical. Take the human heart, for example, with its
exquisite system of valves, or take the eye or the 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 regarding the plant may be
re-stated with regard to the animal. Every particle that enters into
the composition of the 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 be
introduced, we must conclude that, given the relation of any
molecule of the body to its environment, its position in the body
might be predicted. 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 man now possesses.
Given this expansion, and given 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 connection. 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 endeavor to be a little
more precise here. I hardly imagine that any profound scientific
thinker who has reflected upon the subject exists, who would not
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; that this relation of physics to consciousness is 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 phenomenon 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 still remain
unanswered.
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, as the human mind is at present constituted, that he
can pass beyond it. 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 connection of the
body and soul is as insoluble in its modern form as it was in the
pre-scientific ages. Phosphorus is known to enter into the
composition of the human brain, and a courageous writer has
exclaimed, in his trenchant German, “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 also is mute in reply to these questions. But
if the materialist is confounded, and science rendered dumb, who
else is entitled to answer? To whom has the secret been revealed?
Let us lower our heads and acknowledge our ignorance, 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 does 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.
II.
On Haze and Dust.
Solar light in passing through a dark room reveals its track by
illuminating the dust floating in the air. “The sun,” says Daniel
Culverwell, “discovers atomes, though they be invisible by
candle-light, and makes them dance naked in his beams.”
In my researches on the decomposition of vapors by light, I was
compelled to remove these “atomes” and this dust. It was essential
that the space containing the vapors should embrace no visible
thing; that no substance capable of scattering the light in the
slightest sensible degree should, at the outset of an experiment, be
found in the “experimental tube” traversed by the luminous beam.
For a long time I was troubled by the appearance there of floating
dust, which, though invisible in diffuse daylight, was at once
revealed by a powerfully condensed beam. Two tubes were placed in
succession in the path of the dust: the one containing fragments of
glass wetted with concentrated sulphuric acid; the other, fragments
of marble wetted with a strong solution of caustic potash. To my
astonishment it passed through both. The air of the Royal
Institution, sent through these tubes at a rate sufficiently slow to
dry it and to remove its carbonic acid, carried into the
experimental tube a considerable amount of mechanically-suspended
matter, which was illuminated when the beam passed through the tube.
The effect was substantially the same when the air was permitted to
bubble through the liquid acid and through the solution of potash.
Thus, on the 5th of October, 1868, successive charges of air were
admitted through the potash and sulphuric acid into the exhausted
experimental tube. Prior to the admission of the air the tube was
_optically empty_; it contained nothing competent to scatter the
light. After the air had entered the tube, the conical track of the
electric beam was in all cases clearly revealed. This, indeed, was a
daily observation at the time to which I now refer.
I tried to intercept this floating matter in various ways; and on
the day just mentioned, prior to sending the air through the drying
apparatus, I carefully permitted it to pass over the tip of a
spirit-lamp flame. The floating matter no longer appeared, having
been burnt up by the flame. It was, therefore, _organic matter_.
When the air was sent too rapidly through the flame, a fine blue
cloud was found in the experimental tube. This was the _smoke_ of
the organic particles. I was by no means prepared for this result;
for I had thought, with the rest of the world, that the dust of our
air was, in great part, inorganic and non-combustible.
Mr. Valentin had the kindness to procure for me a small gas-furnace,
containing a platinum tube, which could be heated to vivid redness.
The tube also contained a roll of platinum gauze, which, while it
permitted the air to pass through it, insured the practical contact
of the dust with the incandescent metal. The air of the laboratory
was permitted to enter the experimental tube, sometimes through the
cold, and sometimes through the heated tube of platinum. The
rapidity of admission was also varied. In the first column of the
following table the quantity of air operated on is expressed by the
number of inches which the mercury gauge of the air-pump sank when
the air entered. In the second column the condition of the platinum
tube is mentioned, and in the third the state of the air which
entered the experimental tube.
State of State of
Quantity Platinum Experimental
of Air. Tube. Tube.
15 inches Cold Full of particles.
15 inches Red-hot Optically empty.
15 inches Cold Full of particles.
15 inches Red-hot Optically empty.
15 inches Cold Full of particles.
15 inches Red-hot Optically empty.