convinced him that he had fallen into error—that the transformation of the homogeneous into the heterogeneous does not sum up the whole of evolution, but only the most conspicuous part of the secondary redistribution of matter and motion constituting it. Many changes in the direction of increasing heterogeneity—e. g., the rise of a cancer in the individual organism, or of a revolution in the state—obviously tend not to evolution, but to dissolution. When, then, does increase in complexity mean evolution? The answer to this question, found in a return to the principle of integration, is, when increase of complexity is accompanied by more and more complete interdependence among the specialized parts—by increase in organic unification. Evolution, therefore, may be roughly defined as change toward multiformity in unity, brought about by the rise of unlikenesses (differentiation) and the concentration of the unlike parts, through mutual dependence, into an organized whole (integration); or, to phrase the doctrine philosophically in Mr. Spencer's world-famous formula, as "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."
But with the formulation of this all-pervading process, we reach only the starting-point of a fresh investigation. Philosophy—the complete unification of knowledge—demands the restatement of the law of evolution in deductive form. Such being the transformations manifested by all classes of concrete phenomena, we ask. Why this continuous metamorphosis? We must seek the rationale of the universal changes inductively set forth, must undertake to interpret them as necessary consequences of some deeper law.
Incidentally we may notice here the firm, logical consistency of the Spencerian system. While it presents us with a history of the knowable universe in empirical generalizations, it also affiliates these all-embracing generalizations upon ultimate principles, derives them from its final dictum, and thus furnishes a rational history of the knowable universe as well. Undertaking, therefore, the task of presenting the phenomena of evolution in synthetic order, Mr. Spencer arrives at the law of the instability of any finite homogeneous aggregate owing to the unequal exposure of its parts to incident forces, and proceeds to show, first, that "every mass, or part of a mass, on which a force falls subdivides and differentiates that force, which thereupon proceeds to work a variety of changes"; and, secondly, that the process of segregation, "tending ever to separate unlike units and to bring together like units," serves constantly "to sharpen or make definite differentiations otherwise caused." Finally, these laws—the instability
