gests a definition of evolution in its most general form:[1] "Aristotle solved the fundamental problem of Greek philosophy, viz., how behind the changing multiplicity of phenomena a unitary and abiding being is to be thought—by means of a concept of relation, that of development."[2] In other words, this concept is a means for thinking the relation between the changing and the permanent, between being and becoming. These two definitions amount substantially to the same thing. They may both be translated into terms of "differentiation and integration." On the one side, increasing coherency stands for the integrating, unifying tendency, and on the other, definiteness and heterogeneity may be expressed as the diversifying tendency. (It seems needless in so general a definition to separate 'definiteness' and 'heterogeneity' as independent conceptions: we mean by a 'definite thing' one which has limitations or determinations, and that is precisely what we understand by a 'heterogeneous thing.' The more we multiply the limits or determinations of anything, the more we increase its heterogeneity and definiteness. The two conceptions involve each other.) The principle of evolution, then, may be expressed as the process of integration in differentiation, of unity working through diversity. In the organic world, it is that conception "according to which the whole connected system of organic and animate beings is regarded as the single process of a development of organic forms, determined by the teleological point of view of fitness for life."[3] The essential idea in the principle of evolution may be conveniently brought out by contrasting with it one or two other ways in which men have thought this relation of unity to diversity. Pantheism, for example, offers the idea that particulars are different stages or conditions of substance; evolution, that particulars are different moments in a single process. One is static, the other dynamic. The essential notion in evolution is that the transformation continues always to go on. Again , in contrasting the principle of evolution with the principle of emanation, we find this difference: that, according to the doc-
