Sir John Herschel drew some startling conclusions regarding the
density and weight of comets. You know that these extraordinary and
mysterious bodies sometimes throw out tails 100,000,000 miles in
length, and 50,000 miles in diameter. The diameter of our earth is
8,000 miles. Both it and the sky, and a good portion of space beyond
the sky, would certainly be included in a sphere 10,000 miles across.
Let us fill a hollow sphere of this diameter with cometary matter, and
make it our unit of measure. To produce a comet's tail of the size
just mentioned, about 300,000 such measures would have to be emptied
into space. Now suppose the whole of this stuff to be swept together,
and suitably compressed, what do you suppose its volume would be? Sir
John Herschel would probably tell you that the whole mass might be
carted away, at a single effort, by one of your dray-horses. In fact,
I do not know that he would require more than a small fraction of a
horse-power to remove the cometary dust. After this, you will hardly
regard as monstrous a notion I have sometimes entertained, concerning
the quantity, of matter in our sky. Suppose a shell to surround the
earth at a distance which would place it beyond the grosser matter
that hangs in the lower regions of the air--say at the height of the
Matterhorn or Mont Blanc. Outside this shell we should have the deep
blue firmament. Let the atmospheric space beyond the shell be swept
clean, and the sky-matter properly gathered up. What would be its
probable amount? I have sometimes thought that a lady's portmanteau
would contain it all. I have thought that even a gentleman's
portmanteau--possibly his snuff-box--might take it in. And, whether
the actual sky be capable of this amount of condensation or not, I
entertain no doubt that a sky quite as vast as ours, and as good in
appearance, could be formed from a quantity of matter which might be
held in the hollow of the hand.
Small in mass, the vastness in point of number of the particles of our
sky may be inferred from the continuity of its light. It is not in
broken patches, nor at scattered points, that the heavenly azure is
revealed. To the observer on the summit of Mont Blanc, the blue is as
uniform and coherent as if it formed the surface of the most
close-grained solid. A marble dome would not exhibit a stricter
continuity. And Mr. Glaisher will inform you, that if our
hypothetical shell were lifted to twice the height of Mont Blanc above
the earth's surface, we should still have the azure overhead.
Everywhere through the atmosphere those sky-particles are strewn. They
fill the Alpine valleys, spreading like a delicate gauze in front of
the slopes of pine. They sometimes so swathe the peaks with light as
to abolish their definition. This year I have seen the Weisshorn thus
dissolved in opalescent air. By proper instruments the glare thrown
from the sky-particles against the retina may be quenched, and then
the mountain which it obliterated starts into sudden definition.
[Footnote: See the 'Sky of the Alps,' Art. iv. sec. 3, vol. i.]
Its extinction in front of a dark mountain resembles exactly the
withdrawal of a veil. It is then the light taking possession of the
eye, not the particles acting as opaque bodies, that interferes with
the definition. By day this light quenches the stars; even by
moonlight it is able to exclude from vision all stars between the
fifth and the eleventh magnitude. It may be likened to a noise, and
the feebler stellar radiance to a whisper drowned by the noise.
What is the nature of the particles which shed this light? The
celebrated De la Rive ascribes the haze of the Alps in fine weather to
floating organic germs. Now the possible existence of germs in such
profusion has been held up as an absurdity. It has been affirmed that
they would darken the air, and on the assumed impossibility of their
existence in the requisite numbers, without invasion of the solar
light, an apparently powerful argument has been based by believers in
spontaneous generation. Similar arguments have been used by the
opponents of the germ theory of epidemic disease, who have
triumphantly challenged an appeal to the microscope and the chemist's
balance to decide the question. Such arguments, however, are founded
on a defective acquaintance with the powers and properties of matter.
Without committing myself in the least to De la Rive's notion, to the
doctrine of spontaneous generation, or to the germ theory of disease,
I would simply draw attention to the demonstrable fact, that, in the
atmosphere, we have particles which defy both the microscope and the
balance, which do not darken the air, and which exist, nevertheless,
in multitudes sufficient to reduce to insignificance the Israelitish
hyperbole regarding the sands upon the sea-shore.
*****
The varying judgments of men on these and other questions may perhaps
be, to some extent, accounted for by that doctrine of Relativity which
plays so important a part in philosophy. This doctrine affirms that
the impressions made upon us by any circumstance, or combination of
circumstances, depend upon our previous state. Two travellers upon
the same height, the one having ascended to it from the plain, the
other having descended to it from a higher elevation, will be
differently affected by the scene around them. To the one nature is
expanding, to the other it is contracting, and impressions which have
two such different antecedent states are sure to differ. In our
scientific judgments the law of relativity may also play an important
part. To two men, one educated in the school of the senses, having
mainly occupied himself with observation; the other educated in the
school of imagination as well, and exercised in the conceptions of
atoms and molecules to which we have so frequently referred, a bit of
matter, say 1/50000th of an inch in diameter, will present itself
differently. The one descends to it from his molar heights, the other
climbs to it from his molecular lowlands. To the one it appears
small, to the other large. So, also, as regards the appreciation of
the most minute forms of life revealed by the microscope. To one of
the men these naturally appear conterminous with the ultimate
particles of matter; there is but a step from the atom to the
organism. The other discerns numberless organic gradations between
both. Compared with his atoms, the smallest vibrios and bacteria of
the microscopic field are as behemoth and leviathan. The law of
relativity may to some extent explain the different attitudes of two
such persons with regard to the question of spontaneous generation. An
amount of evidence which satisfies the one entirely fails to satisfy
the other; and while to the one the last bold defence and startling
expansion of the doctrine by Dr. Bastian will appear perfectly
conclusive, to the other it will present itself as merely imposing a
labour of demolition on subsequent investigators. [Footnote: When
these words were uttered I did not imagine that the chief labour of
demolition would fall upon myself. 1878.]
Let me say here that many of our physiological observers appear to
form a very inadequate estimate of the distance which separates the
microscopic from the molecular limit, and that, as a consequence, they
sometimes employ a phraseology calculated to mislead. When, for
example, the contents of a cell are described as perfectly homogeneous
or as absolutely structureless, because the microscope fails to
discover any structure; or when two structures are pronounced to be
without difference, because the microscope can discover none, then, I
think the microscope begins to play a mischievous part. A little
consideration will make it plain that the microscope can have no voice
in the question of germ structure. Distilled water is more perfectly
homogeneous than any possible organic germ. What is it that causes
the liquid to cease contracting at 39 degrees Fahr, and to expand
until it freezes? We have here a structural process of which the
microscope can take no note, nor is it likely to do so by any
conceivable extension of its powers. Place distilled water in the
field of an electro-magnet, and bring a microscope to bear upon it.
Will any change be observed when the magnet is excited? Absolutely
none; and still profound and complex changes have occurred. First of
all, the particles of water have been rendered diamagnetically polar;
and secondly, in virtue of the structure impressed upon it by the
magnetic whirl of its molecules, the liquid twists a ray of light in a
fashion perfectly determinate both as to quantity and direction.
Have the diamond, the amethyst, and the countless other crystals
formed in the laboratories of nature and of man no structure?
Assuredly they have; but what can the microscope make of it? Nothing.
It cannot be too distinctly borne in mind that between the microscopic
limit, and the true molecular limit, there is room for infinite
permutations and combinations. It is in this region that the poles of
the atoms are arranged, that tendency is given to their powers; so
that when these poles and powers have free action, proper stimulus,
and a suitable environment, they determine, first the germ, and
afterwards the complete organism. This first marshalling of the
atoms, on which all subsequent action depends, baffles a keener power
than that of the microscope. When duly pondered, the complexity of
the problem raises the doubt, not of the power of our instrument, for
that is nil, but whether we ourselves possess the intellectual
elements which will ever enable us to grapple with the ultimate
structural energies of nature. [Footnote: 'In using the expression
"one sort of living substance" I must guard against being supposed to
mean that any kind of living protoplasm is homogeneous. Hyaline
though it may appear, we are not at present able to assign any limit
to its complexity of structure.'--Burdon Sanderson, in the 'British
Medical Journal,' January 16, 1875. We have here scientific insight,
and its correlative caution. In fact Dr. Sanderson' s important
researches are a continued illustration of the position laid down
above.]
In more senses than one Mr. Darwin has drawn heavily upon the
scientific tolerance of his age. He has drawn heavily upon time in
his development of species, and he has drawn adventurously upon matter
in his theory of pangenesis. According to this theory, a germ,
already microscopic, is a world of minor germs. Not only is the
organism as a whole wrapped up in the germ, but every organ of the
organism has there its special seed. This, I say, is an adventurous
draft on the power of matter to divide itself and distribute its
forces. But, unless we are perfectly sure that he is overstepping the
bounds of reason, that he is unwittingly sinning against observed fact
or demonstrated law--for a mind like that of Darwin can never sin
wittingly against either fact or law--we ought, I think, to be
cautious in limiting his intellectual horizon. If there be the least
doubt in the matter, it ought to be given in favour of the freedom of
such a mind. To it a vast possibility is in itself a dynamic power,
though the possibility may never be drawn upon. It gives me pleasure
to think that the facts and reasonings of this discourse tend rather
towards the justification of Mr. Darwin, than towards his
condemnation; for they seem to show the perfect competence of matter
and force, as regards divisibility and distribution, to bear the
heaviest strain that he has hitherto imposed upon them.
In the case of Mr. Darwin, observation, imagination, and reason
combined have run back with wonderful sagacity and success over a
certain length of the line of biological succession. Guided by
analogy, in his 'Origin of Species' he placed at the root of life a
primordial germ, from which he conceived the amazing variety of the
organisms now upon earth's surface might be deduced. If this
hypothesis were even true, it would not be final. The human mind
would infallibly look behind the germ, and however hopeless the
attempt, would enquire into the history of its genesis. In this dim
twilight of conjecture the searcher welcomes every gleam, and seeks to
augment his light by indirect incidences. He studies the methods of
nature in the ages and the worlds within his reach, in order to shape
the course of speculation in antecedent ages and worlds. And though
the certainty possessed by experimental enquiry is here shut out, we
are not left entirely without guidance. From the examination of the
solar system, Kant and Laplace came to the conclusion that its various
bodies once formed parts of the same undislocated mass; that matter in
a nebulous form preceded matter in its present form; that as the ages
rolled away, heat was wasted, condensation followed, planets were
detached; and that finally the chief portion of the hot cloud reached,
by self-compression, the magnitude and density of our sun. The earth
itself offers evidence of a fiery origin; and in our day the
hypothesis of Kant and Laplace receives the independent countenance of
spectrum analysis, which proves the same substances to be common to
the earth and sun.
Accepting some such view of the construction of our system as
probable, a desire immediately arises to connect the present life of
our planet with the past. We wish to know something of our remotest
ancestry. On its first detachment from the central mass, life, as we
understand it, could not have been present on the earth. How, then,
did it come there? The thing to be encouraged here is a reverent
freedom--a freedom preceded by the hard discipline which checks
licentiousness in speculation--while the thing to be repressed, both
in science and out of it, is dogmatism. And here I am in the hands of
the meeting--willing to end, but ready to go on. I have no right to
intrude upon you, unasked, the unformed notions which are floating
like clouds, or gathering to more solid consistency, in the modern
speculative scientific mind. But if you wish me to speak plainly,
honestly, and undisputatiously, I am willing to do so. On the present
occasion--
You are ordained to call, and I to come.
Well, your answer is given, and I obey your call.
Two or three years ago, in an ancient London College, I listened to a
discussion at the end of a lecture by a very remarkable man. Three or
four hundred clergymen were present at the lecture. The orator began
with the civilisation of Egypt in the time of 'Joseph; pointing out
the very perfect organisation of the kingdom, and the possession of
chariots, in one of which Joseph rode, as proving a long antecedent
period of civilisation. He then passed on to the mud of the Nile, its
rate of augmentation, its present thickness, and the remains of human
handiwork found therein: thence to the rocks which bound the Nile
valley, and which teem with organic remains. Thus in his own clear
way he caused the idea of the world's age to expand itself
indefinitely before the minds of his audience, and he contrasted this
with the age usually assigned to the world. During his discourse he
seemed to be swimming against a stream, he manifestly thought that he
was opposing a general conviction. He expected resistance in the
subsequent discussion; so did I. But it was all a mistake; there was
no adverse current, no opposing conviction, no resistance; merely here
and there a half-humorous, but unsuccessful attempt to entangle him in
his talk. The meeting agreed with all that had been said regarding
the antiquity of the earth and of its life. They had, indeed, known
it all long ago, and they rallied the lecturer for coming amongst them
with so stale a story. It was quite plain that this large body of
clergymen, who were, I should say, to be ranked amongst the finest
samples of their class, had entirely given up the ancient landmarks,
and transported the conception of life's origin to an indefinitely
distant past.
This leads us to the gist of our present enquiry, which is this: Does
life belong to what we call matter, or is it an independent principle
inserted into matter at some suitable epoch--say when the physical
conditions became such as to permit of the development of life? Let
us put the question with the reverence due to a faith and culture in
which we all were cradled, and which are the undeniable historic
antecedents of our present enlightenment. I say, let us put the
question reverently, but let us also put it clearly and definitely.
There are the strongest grounds for believing that during a certain
period of its history the earth was not, nor was it fit to be, the
theatre of life. Whether this was ever a nebulous period, or merely a
molten period, does not signify much; and if we revert to the nebulous
condition, it is because the probabilities are really on its side. Our
question is this: Did creative energy pause until the nebulous matter
had condensed, until the earth had been detached, until the solar fire
had so far withdrawn from the earth's vicinity as to permit a crust to
gather round the planet? Did it wait until the air was isolated;
until the seas were formed; until evaporation, condensation, and the
descent of rain had begun; until the eroding forces of the atmosphere
had weathered and decomposed the molten rocks so as to form soils;
until the sun's rays had become so tempered by distance, and by waste,
as to be chemically fit for the decompositions necessary to vegetable
life? Having waited through these aeons until the proper conditions
had set in, did it send the flat forth, 'Let there be Life!'? These
questions define a hypothesis not without its difficulties, but the
dignity of which in relation to the world's knowledge was demonstrated
by the nobleness of the men whom it sustained.
Modern scientific thought is called upon to decide between this
hypothesis and another; and public thought generally will afterwards
be called upon to do the same. But, however the convictions of
individuals here and there may be influenced, the process must be slow
and secular which commends the hypothesis of Natural Evolution to the
public mind. For what are the core and essence of this hypothesis?
Strip it naked, and you stand face to face with the notion that not
alone the more ignoble forms of animalcular or animal life, not alone
the nobler forms of the horse and lion, not alone the exquisite and
wonderful mechanism of the human body, but that the human mind
itself--emotion, intellect, will, and all their phenomena--were once
latent in a fiery cloud. Surely the mere statement of such a notion
is more than a refutation. But the hypothesis would probably go even
farther than this. Many who hold it would probably assent to the
position that, at the present moment, all our philosophy, all our
poetry, all our science, and all our art--Plato, Shakspeare, Newton,
and Raphael--are potential in the fires of the sun. We long to learn
something of our origin. If the Evolution hypothesis be correct, even
this unsatisfied yearning must have come to us across the ages which
separate the primeval mist from the consciousness of to-day. I do not
think that any holder of the Evolution hypothesis would say that I
overstate or overstrain it in any way. I merely strip it of all
vagueness, and bring before you, unclothed and unvarnished, the
notions by which it must stand or fall.
Surely these notions represent an absurdity too monstrous to be
entertained by any sane mind. But why are such notions absurd, and
why should sanity reject them? The law of Relativity, of which we
have previously spoken, may find its application here. These
Evolution notions are absurd, monstrous, and fit only for the
intellectual gibbet, in relation to the ideas concerning matter which
were drilled into us when young. Spirit and matter have ever been
presented to us in the rudest contrast, the one as all-noble, the
other as all-vile. But is this correct? Upon the answer to this
question all depends. Supposing that, instead of having the foregoing
antithesis of spirit and matter presented to our youthful minds, we
had been taught to regard them as equally worthy, and equally
wonderful; to consider them, in fact, as two opposite faces of the
self-same mystery. Supposing that in youth we had been impregnated
with the notion of the poet Goethe, instead of the notion of the poet
Young, and taught to look upon matter, not as 'brute matter,' but as
the 'living garment of God;' do you not think that under these
altered circumstances the law of Relativity might have had an outcome
different from its present one? Is it not probable that our
repugnance to the idea of primeval union between spirit and matter
might be considerably abated? Without this total revolution of the
notions now prevalent, the Evolution hypothesis must stand condemned;
but in many profoundly thoughtful minds such a revolution has already
taken place. They degrade neither member of the mysterious duality
referred to; but they exalt one of them from its abasement, and repeal
the divorce hitherto existing between them. In substance, if not in
words, their position as regards the relation of spirit and matter is:
'What God hath joined together, let not man put asunder.'
You have been thus led to the outer rim of speculative science, for
beyond the nebulae scientific thought has never hitherto ventured. I
have tried to state that which I considered ought, in fairness, to be
outspoken. I neither think this Evolution hypothesis is to be flouted
away contemptuously, nor that it ought to be denounced as wicked. It
is to be brought before the bar of disciplined reason, and there
justified or condemned. Let us hearken to those who wisely support
it, and to those who wisely oppose it; and let us tolerate those,
whose name is legion, who try foolishly to do either of these things.
The only thing out of place in the discussion is dogmatism on either
side. Fear not the Evolution hypothesis. Steady yourselves, in its
presence, upon that faith in the ultimate triumph of truth which was
expressed by old Gamaliel when he said: 'If it be of God, ye cannot
overthrow it; if it be of man, it will come to nought.' Under the
fierce light of scientific enquiry, it is sure to be dissipated if it
possess not a core of truth. Trust me, its existence as a hypothesis
is quite compatible with the simultaneous existence of all those
virtues to which the term 'Christian' has been applied. It does not
solve--it does not profess to solve--the ultimate mystery of this
universe. It leaves, in fact, that mystery untouched. For, granting
the nebula and its potential life, the question, whence they came,
would still remain to baffle and bewilder us. At bottom, the
hypothesis does nothing more than 'transport the conception of life's
origin to an indefinitely distant past.'