SCIENCE. 
1 86 
objection made by a well-known writer , 8 that we might as 
well speak of “ a watch force” as of “ a vital force,” is an 
objection which has no validity, and is chargeable with the 
great vice of confounding one of the clearest distinctions 
which exist in Nature. The rule which should govern 
language is very plain. Every phenomenon or group 
of phenomena which is clearly separate from all others, 
should have a name as separate and distinctive as 
itself. The absurdity of speaking of a “watch force” 
lies in this — that the force by which a watch goes 
is not separable from the force by which many other 
mechanical movements are effected. It is a force which 
is otherwise well-known and can be fully expressed in other 
and more definite terms. That force is simply the elasticity 
of a coiled spring. But the phenomena of Life are not due 
to any force which can be fully and definitely expressed in 
other terms. It is not purely chemical, nor purely me- 
chanical, nor purely electrical, nor reducible to any other 
more simple and elementary conception. The popular use, 
therefore, which keeps up separate words and phrases by 
which to describe and designate the phenomena of Life, is 
a use which is correct and thoroughly expressive of the 
truth. There is nothing more fallacious in philosophy than 
the endeavor by mere tricks of language, to suppress and 
keep out of sight the distinctions which Nature proclaims 
with a loud voice. 
It is thus, also, that because certain creatures widely 
separate in the scale of being may be traced back to some 
embryonic stage, in which they are undistinguishable, it 
has become fashionable to sink the vast differences which 
must lie hid under this uniformity of aspect and of material 
composition under some vague form of words in which the 
mind makes, as it were, a covenant with itself not to think 
of such differences as are latent and invisible, however 
important we know them to be by the differences of result 
to which they lead. Thus it is common now to speak of 
things widely separated in rank and functions being the 
same, only “differentiated,” or “variously conditioned.” 
In these, and in all similar cases, the differences which 
are unseen, or which, if seen are set aside, are often of in- 
finitely greater importance than the similarities which are 
selected as the characteristics chiefly worthy of regard. If, 
for example, in the albumen of an egg there be no discern- 
ible differences either of structure or of chemical composi- 
tion, but if, nevertheless, by a mere application of a little 
heat, part of it is “differentiated” into blood, another part 
of it into flesh, another part of it into bone, another part of 
it into feathers, and the whole into one perfect organic 
structure, it is clear that any purely chemical definition of 
this albumen, or any purely mechanical definition of it, 
would not merely fail of being complete, but would abso- 
lutely pass by and pass over the one essential character- 
istic of vitality which makes it what it is, and determines 
what it is to be in the system of Nature. 
Let us always remember that the more perfect may be 
the apparent identity between two things which afterwards 
become widely different, the greater must be the power and 
value of those invisible distinctions — of those unseen fact- 
ors — which determine the subsequent divergence. These 
distinctions are invisible, not merely because our methods 
of analysis are too coarse to detect them, but because ap- 
parently they are of a nature which no physical dissection 
and no chemical analysis could possibly reveal. Some 
scientific men are fond of speaking and thinking of these 
invisible factors as distinctions due to differences in 
“ molecular arrangement,” as if the more secret agencies 
of Nature gave us the idea of depending on nothing else 
than mechanical arrangement — on differences in the shape 
or in the position of the molecules of matter. But this is 
by no means true. No doubt there are such differences — 
as far beyond the reach of the miscroscope as the differ- 
ences which the microscope does reveal are beyond the 
reach of our unaided vision. But we know enough of the 
different agencies which must lie hid in things apparently 
the same to be sure that the divergences of work which 
these agencies produce do not depend upon, or consist in, 
mere differences of mechanical arrangement. We know 
enough of those agencies to be sure that they are agencies 
3 Mr. G. H. Lewes. 
which do, indeed, determine both arrangement and compo- 
sition, but do not themselves consist in either. 
This is the conclusion to which we are brought by facts 
which are well known. There are structures in Nature 
which can be seen in the process of construction. There 
are conditions of matter in which its particles can be seen 
rushing under the impulse of invisible forces to take their 
appointed place in the form which to them is a law. Such 
are the facts visible in the processes of crystallization. 
In them we can see the particles of matter passing 
from one “molecular condition” to another; and it is 
impossible that this passage can be ascribed either to 
the old arrangement which is broken up, or to the 
new arrangement which is substituted in its stead. 
Both structures have been built up out of elementary 
materials by some constructive agency which is the 
master and not the servant — the cause and not the con- 
sequence of the movements which are effected, and of 
the arrangement which is their result. And if this be true 
of crystalline forms in the mineral kingdom, much more 
is it true of organic forms in the animal kingdom. Crystals 
are, as it were, the beginnings of Nature’s architecture, her 
lowest and simplest forms of building. But the most com- 
plex crystalline forms which exist — and many of them are 
singularly complex and beautiful — are simplicity itself com- 
pared with the very lowest organism which is endowed with 
Life. In them, therefore, still more than in the formation of 
crystals, the work of “ differentiation ” — that is to say, the 
work of forming out of one material different structures for 
the discharge of different functions — is the work of agencies 
which are invisible and unknown ; and it is in these agencies, 
not in the molecular arrangements which they cause, that 
the essential character and individuality of every organism 
consists. Accordingly in the development of seeds and of 
eggs, which are the germs of plants and animals respectively, 
the particles of matter can be traced moving, in obedience to 
forces which are unforseen, from “molecular conditions” 
which appear to be those of almost complete homogeneity 
to other molecular conditions which are of inconceivable 
complexity. In that mystery of all mysteries, of which 
physicists talk so glibly, the living “ nucleated cell,” the 
great work of creation may be seen in actual operation, not 
caused by “molecular condition,” but determining it, and, 
from elements which to all our senses, and to all our means 
of investigation, appear absolutely the same, building up the 
molecules of Protoplasm, now into a sea-weed, now into a 
cedar of Lebanon, now into an insect, now into a fish, now 
into a reptile, now into a bird, now into a man. And in 
proportion as the molecules of matter do not seem to be the 
masters but the servants here, so do the forces which dis- 
pose of them stand out separate and supreme. In every 
germ this development can only be “ after its kind.” The 
molecules must obey ; but no mere wayward or capricious 
order can be given to them. The formative energies seem to 
be as much under command as the materials upon which 
they work. For, invisible, intangible, and imponderable as 
these forces are — unknown and even inconceivable as they 
must be in their ultimate nature — enough can be traced of 
their working to assure that they are all closely related to 
each other, and belong to a system which is one. Out of 
the chemical elements of Nature, in numerous but definite 
combinations, it is the special function of vegetable life to 
lay the foundations of organic mechanism ; whilst it is the 
special function of animal life to take in the materials thus 
supplied, and to build them up into the highest and most 
complicated stuctures. This involves a vast cycle of opera- 
tions, as to the unity of which we cannot be mistaken — for 
it is a cycle of operations obviously depending on adjust- 
ments among all the forces both of solar and terrestrial 
physics — and every part of this vast series of adjustments 
must be in continuous and unbroken correlation with the 
rest. 
Thus every step in the progress of science which tends to 
reduce all organisms to one and the same set of elementary 
substances, or to one and the same initial structure, only 
adds to the certainty with which we conclude that it is upon 
| something else than composition, and upon something else 
than structure, that those vast differences ultimately depend 
which separate so widely between living things in rank, in 
function and in power. And although we cannot tell what 
l that something is — although science does not as yet even 
