Page:Philosophical Review Volume 19.djvu/266

252 and interesting changes, the description of which forms so prominent a part of Spencer's work.

These special conditions, the existence of masses of considerable size and of a comparatively slow process of change, are always satisfied in the phenomena with which we commonly associate the term evolution. Alike in the slowly cooling and aggregating nebula, the developing organism, and in those still more involved complexes found in the institutions of human society, the slowly changing masses are subject to and affected by an infinite variety of incident forces. The last example will not be convincing to those unfamiliar with these conceptions, but Spencer has shown by a wealth of illustration that the same conditions apply, and that human societies, under the aspect of matter in motion, can be described in the same terms.

The main changes occasioned by the secondary redistribution of slowly evolving matter are described by Spencer as increase in the qualities of definiteness, coherence and heterogeneity, so that this involved analysis leads to the famous formula of evolution, which has been so often quoted and so widely discussed.

"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." Concerning this formula the intelligent critic will naturally be inclined to ask three pertinent questions:—What does it mean? Is it true? If true what is its practical value and validity? How far and within what limits does it give us a clue which will help us to unravel some of the complexities of natural phenomena?

The first of these is not easy to answer in a few words. It is impossible here to give any idea of the manner in which Spencer