and perhaps to the rhythms of climatic change; from the oscillations of molecules to the rise and fall of nations and the birth and death of stars.
All these "laws of the knowable" are reducible (by an analysis which must not here be followed in detail) to the final law of the persistence of force. But there is something static and inert about this principle; it does not so much as hint at the secret of life. What is the dynamic principle of reality? What is the formula of the growth and decay of all things? It must be a formula of evolution and dissolution, for "an entire history of anything must include its appearance out of the imperceptible and its disappearance into the imperceptible."[1]
So Spencer offers us his famous formula of evolution, which made the intellect of Europe gasp for breath, and required ten volumes and forty years for its explanation. "Evolution is an integration of matter and a 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."[2] What does this mean?
The growth of planets out of nebulae; the formation of oceans and mountains on the earth; the metabolism of elements by plants, and of animal tissues by men; the development of the heart in the embryo, and the fusion of bones after birth; the unification of sensations and memories into knowledge and thought, and of knowledge into science and philosophy; the development of families into clans and gentes and cities and states and alliances and the "federation of the world": here is the integration of matter,—the aggregation of separate items into masses and groups and wholes. Such integration of course involves a lessening of motion in the parts, as the growing power of the state lessens the freedom of the individual; but at the same time it gives to the parts an inter-
