ously increased in precision. Accuracy of evolutions is given by perpetual drill; so that in battle, men and the regiments formed of them, are made to take definite positions and perform definite acts at definite times. Once more, there has gone on that integration by which the multiform actions of an army are directed to a single end. By a co-ordinating apparatus having the commander-in-chief for its centre, the charges, and halts, and retreats are duly concerted; and a hundred thousand individual actions are united under one will.

The progress here so clearly marked, is a progress traceable throughout social functions at large. Comparing the rule of a savage chief with that of a civilized government, aided by its subordinate local governments and their officers, down to the police in the streets, we see how, as men have advanced from tribes of tens to nations of millions, the regulative process has grown large in amount; how, guided by written laws, it has passed from vagueness and irregularity to comparative precision; and how it has sub-divided into processes increasingly multiform. Or observing how the barter that goes on among barbarians, differs from our own commercial processes, by which a million's worth of commodities is distributed daily; by which the relative values of articles immensely varied in kinds and qualities are measured, and the supplies adjusted to the demands; and by which industrial activities of all orders are so combined that each depends on the rest and aids the rest; we see that the kind of action which constitutes trade, has become progressively more vast, more varied, more definite, and more integrated.

§ 145. A finished conception of Evolution we thus find to be one which includes the re-distribution of the retained motion, as well as that of the component matter. This added element of the conception is scarcely, if at all, less important than the other. The movements of the Solar

System have for us a significance equal to that which the sizes, forms, and relative distances of its members possess. And of the phenomena presented by an organism, it must be admitted that the combined sensible and insensible actions we call its life, do not yield in interest to its structural traits. Leaving out, however, all implied reference to the way in which these two orders of facts concern us, it is clear that with each re-distribution of matter there necessarily goes a re-distribution of motion; and that the unified knowledge constituting Philosophy, must comprehend both aspects of the transformation.

While, then, we have to contemplate the matter of an evolving aggregate as undergoing, not progressive integration simply, but as simultaneously undergoing various secondary re-distributions; we have also to contemplate the motion of an evolving aggregate, not only as being gradually dissipated, but as passing through many secondary re-distributions on the way toward dissipation. As the structural complexities that arise during compound evolution, are incidental to the progress from the extreme of diffusion to the extreme of concentration; so the functional complexities accompanying them, are incidental to the progress from the greatest quantity of contained motion to the least quantity of contained motion. And we have to state these concomitants of both transformations, as well as their beginnings and ends.

Our formula, therefore, needs an additional clause. To combine this satisfactorily with the clauses as they stand in the last chapter, is scarcely practicable; and for convenience of expression it will be best to change their order. Doing this, and making the requisite addition, the formula finally stands thus:-Evolution is an integration of matter and concomitant dissipation of motion; during which the matter passes from an indefinite, incoherent homogeneity to a definite, coherent heterogeneity; and during which the retained motion undergoes a parallel transformation.

CHAPTER XVIII.

THE INTERPRETATION OF EVOLUTION.

§ 146. Is this law ultimate or derivative? Must we rest satisfied with the conclusion that throughout all classes of concrete phenomena such is the course of transformation? Or is it possible for us to ascertain why such is the course of transformation? May we seek for some all-pervading principle which underlies this all-pervading process? Can the inductions set forth in the preceding four chapters be reduced to deductions?

Manifestly this community of result implies community of cause. It may be that of such cause no account can be given, further than that the Unknowable is manifested to us after this mode. Or, it may be that this mode of manifestation is reducible to a simpler mode, from which these many complex effects follow. Analogy suggests the latter inference. Just as it was possible to interpret the empirical generalizations called Kepler's laws, as necessary consequences of the law of gravitation; so it may be possible to interpret the foregoing empirical generalizations as necessary consequences of some deeper law.

Unless we succeed in finding a rationale of this universal metamorphosis, we obviously fall short of that completely unified knowledge constituting Philosophy. As they at present stand, the several conclusions we have lately reached appear to be independent-there is no demonstrated connexion between increasing definiteness and increasing het

erogeneity, or between both and increasing integration. Still less evidence is there that these laws of the re-distribution of matter and motion, are necessarily correlated with those laws of the direction of motion and the rhythm of motion, previously set forth. But until we see these now separate truths to be implications of one truth, our knowledge remains imperfectly coherent.

§ 147. The task before us, then, is that of exhibiting the phenomena of Evolution in synthetic order. Setting out from an established ultimate principle, it has to be shown that the course of transformation among all kinds of existences, cannot but be that which we have seen it to be. It has to be shown that the re-distribution of matter and motion, must everywhere take place in those ways, and produce those traits, which celestial bodies, organisms, societies, alike display. And it has to be shown that this universality of process, results from the same necessity which determines each simplest movement around us, down to the accelerated fall of a stone or the recurrent beat of a harp-string.

In other words, the phenomena of Evolution have to be deduced from the Persistence of Force. As before said"to this an ultimate analysis brings us down; and on this a rational synthesis must build up." This being the ultimate truth which transcends experience by underlying it, so furnishing a common basis on which the widest generalizations stand, these widest generalizations are to be unified by referring them to this common basis. Already the truths manifested throughout concrete phenomena of all orders, that there is equivalence among transformed forces, that motion follows the line of least resistance, and that it is universally rhythmic, we have found to be severally deducible from the persistence of force; and this affiliation of them on the persistence of force has reduced them to a coherent whole. Here we have similarly to affiliate the universal traits of Evolution, by showing that, given the persist

ence of force, the re-distribution of matter and motion necessarily proceeds in such way as to produce them; and by doing this we shall unite them as co-relative aspects of one law, at the same time that we unite this law with the foregoing simpler laws.

§ 148. Before proceeding it will be well to set down some principles that must be borne in mind. In interpreting Evolution we shall have to consider, under their special forms, the various resolutions of force that accompany the re-distribution of matter and motion. Let us glance at such resolutions under their most general forms.

mass.

Any incident force is primarily divisible into its effective and non-effective portions. In mechanical impact, the entire momentum of a striking body is never communicated to the body struck: even under those most favourable conditions in which the striking body loses all its sensible motion, there still remains with it some of the original momentum, under the shape of that insensible motion produced among its particles by the collision. Of the light or heat falling on any mass, a part, more or less considerable, is reflected; and only the remaining part works molecular changes in the Next it is to be noted that the effective force is itself divisible into the temporarily effective and the permanently effective. The units of an aggregate acted on, may undergo those rhythmical changes of relative position which constitute increased vibration, as well as other changes of relative position which are not from instant to instant neutralized by opposite ones. Of these, the first, disappearing in the shape of radiating undulations, leave the molecular arrangement as it originally was; while the second conduce to that re-arrangement characterizing compound Evolution. Yet a further distinction has to be made. The permanently effective force works out changes of relative position of two kinds-the insensible and the sensible. The insensible transpositions among the