out muscular detail, wooden-looking drapery, and faces devoid of individuality, up to the later statues of the Greeks or some of those now produced, the increased accuracy of representation is conspicuous. Compare the mural paintings of the Egyptians with the paintings of mediæval Europe, or these with modern paintings, and the more precise rendering of the appearances of objects is manifest. It is the same with fiction and the drama. In the marvellous tales current among Eastern nations, in the romantic legends of feudal Europe, as well as in the mystery-plays and those immediately succeeding them, we see great want of correspondence to the realities of life; alike in the predominance of supernatural events, in the extremely improbable coincidences, and in the vaguelyindicated personages. Along with social advance, there has been a progressive diminution of unnaturalness—an approach to truth of representation. And now, novels and plays are applauded in proportion to the fidelity with which they exhibit individual characters; improbabilities, like the impossibilities which preceded them, are disallowed; and there is even an incipient abandonment of those elaborate plots which life rarely if ever furnishes.

§ 138. It would be easy to accumulate evidences of other kinds. The progress from myths and legends, extreme in their misrepresentations, to a history that has slowly become, and is still becoming, more accurate; the establishment of settled systematic methods of doing things, instead of the indeterminate ways at first pursued-these might be enlarged upon in further exemplification of the general law. But the basis of induction is already wide enough. Proof that all Evolution is from the indefinite to the definito, we find to be not less abundant than proof that all Evolution is from the homogeneous to the heterogeneous.

It should, however, be added that this advance in definite

ness is not a primary but a secondary phenomenon-is a result incidental on other changes. The transformation of a whole that was originally diffused and uniform into a concentrated combination of multiform parts, implies progressive separation both of the whole from its environment and of the parts from one another. While this is going on there must be indistinctness. Only as the whole gains density, does it become sharply marked off from the space or matter lying outside of it; and only as each separated division draws into its mass those peripheral portions which are at first imperfectly disunited from the peripheral portions of neighbouring divisions, can it acquire anything like a precise outline. That is to say, the increasing definiteness is a concomitant of the increasing consolidation, general and local. While the secondary re-distributions are ever adding to the heterogeneity, the primary re-distribution, while augmenting the integration, is incidentally giving distinctness to the increasingly-unlike parts as well as to the aggregate of them.

But though this universal trait of Evolution is a necessary accompaniment of the traits set forth in preceding chapters, it is not expressed in the words used to describe them. It is therefore needful further to modify our formula. The more specific idea of Evolution now reached is-a change from an indefinite, incoherent homogeneity, to a definite coherent heterogeneity, accompanying the dissipation of motion and integration of matter.

CHAPTER XVII.

THE LAW OF EVOLUTION CONCLuded.

139. The conception of Evolution elaborated in the foregoing chapters, is still incomplete. True though it is it is not the whole truth. The transformations which all things undergo during the ascending phases of their existcnce, we have contemplated under three aspects; and by uniting these three aspects as simultaneously presented, we have formed an approximate idea of the transformations. But there are concomitant changes about which nothing has yet been said; and which, though less conspicuous, are no less essential.

For thus far we have attended only to the re-distributionof Matter, neglecting the accompanying re-distribution of Motion. Distinct or tacit reference has, indeed, repeatedly been made to the dissipation of Motion, that goes on along with the concentration of Matter; and were all Evolution absolutely simple, the total fact would be contained in the proposition that as Motion dissipates Matter concentrates. But while we have recognized the ultimate re-distribution of the Motion, we have passed over its proximate re-distribution. Though something has from time to time been. said about the escaping motion, nothing has been said about the motion that does not escape. In proportion as Evolution becomes compound-in proportion as an aggregate retains, for a considerable time, such a quantity of

motion as permits secondary re-distributions of its component matter, there necessarily arise secondary re-distributions of its retained motion. As fast as the parts are transformed, there goes on a transformation of the sensible or insensible motion possessed by the parts. The parts cannot become progressively integrated, either individually or as a combination, without their motions, individual or combined, becoming more integrated. There cannot arise among the parts heterogeneities of size, of form, of quality, without there also arising heterogeneities in the amounts and directions of their motions, or the motions of their molecules. And increasing definiteness of the parts implies increasing definiteness of their motions. In short, the rhythmical actions going on in each aggregate, must differentiate and integrate at the same time that the structure does so.

The general theory of this re-distribution of the retained motion, must here be briefly stated. Properly to supplement our conception of Evolution under its material aspect by a conception of Evolution under its dynamical aspect, we have to recognize the source of the integrated motions that arise, and to see how their increased multiformity and definiteness are necessitated. If Evolution is a passage of

matter from a diffused to an aggregated state-if while the dispersed units are losing part of the insensible motion which kept them dispersed, there arise among coherent masses of them, any sensible motions with respect to one another; then this sensible motion must previously have existed in the form of insensible motion among the units. If concrete matter arises by the aggregation of diffused matter, then concrete motion arises by the aggregation of diffused motion. That which comes into existence as the movement of masses, implies the cessation of an equivalent molecular movement. While we must leave in the shape of hypothesis the belief that the celestial motions have thus originated, we may sce, as a matter of fact, that this is the

genesis of all sensible motions on the Earth's surface. As before shown (§69), the denudation of lands and deposit of new strata, are effected by water in the course of its descent to the sea, or during the arrest of those undulations produced on it by winds; and, as before shown, the elevation of water to the height whence it fell, is due to solar heat, as is also the genesis of those aerial currents which drift it about when evaporated and agitate its surface when condensed. That is to say, the molecular motion of the etherial medium is transformed into the motion of gases, thence into the motion of liquids, and thence into the motion of solids-stages in each of which a certain amount of molecular motion is lost and an equivalent motion of masses gained. It is the same with organic movements. Certain rays issuing from the Sun, enable the plant to reduce special elements existing in gaseous combination around it, to a solid form-enable the plant, that is, to grow and carry on its functional changes. And since growth, equally with circulation of sap, is a mode of sensible motion, while those rays which have been expended in generating it consist of insensible motions, we have here, too, a transformation of the kind alleged. Animals, derived as their forces are, directly or indirectly, from plants, carry this transformation a step further. The automatic movements of the viscera, together with the voluntary movements of the limbs and body at large, arise at the expense of certain molecular movements throughout the nervous and muscular tissues; and these originally arose at the expense of certain other molecular movements propagated by the Sun to the Earth; so that both the structural and functional motions which organic Evolution displays, are motions of aggregates generated by the arrested motions of units. Even with the aggregates of these aggregates the same rule holds. For among associated men, the progress is ever towards a merging of individual actions in the actions of corporate bodies. While, then,