1 86 



SCIENCE. 



objection made by a well-known writer, 3 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 (rue. No doubt there are such differences — 

 as far beyond the reach of the miscroscopc as the differ- 

 ences which the microscope does reveal are beyond the 

 mm h of our unaided vision. But we know enough of the 

 different agencies which must lie hid in things apparently 

 the same to be sun- thai the divergences of work which 

 iii< se agent les produ< e do nol depend upon, or consist in, 

 mere differences of mechanical arrangement. We know 

 enough of those agencies to be sine 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 arc 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 pan 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, onlj 



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 sepaiate so widely between living things in rank, in 

 function and in power. And although we cannot tell what 

 that something is — although science docs not as yet even 



