_General Principle of the Homogeneity of the Complex and its Components._—The assimilation of brute bodies to living bodies, and of the inorganic kingdom to the organic, was, in the mind of these philosophers, the natural consequence of positing _a priori_ the principles of continuity and evolution. There is, however, a principle underlying these principles. This principle is not expressed explicitly by the philosophers; it is not formulated in precise terms, but is more or less unconsciously implied; it is everywhere applied. It, however, may be clearly seen behind the apparatus of philosophical argument It is the assertion that no arrangement or combination of elements can put forth any new activity essentially different from the activities of the elements of which it is composed. Man is living clay, say Diderot and Cabanis; and, on the other hand, he is a thinking being. _As it is impossible to produce that which thinks from that which does not think_, the clay must possess a rudiment of thought. But is there not another alternative? May not the new phenomenon, thought, be the effect of the arrangement of this clay? If we exclude this alternative, we must then consider arrangement and organization as incapable of producing in arranged and organized matter a new property different from that which it presented before such arrangement. Living protoplasm, says another, is merely an assemblage of brute elements; “these brute elements must therefore possess a rudiment of life.” This is the same implied supposition which we have just considered; if life is not the basis of each element, it cannot result from their simple assemblage. Man and animals are combinations of atoms, says M. le Dantec. It is more natural to admit that human consciousness is the result of the elementary consciousness of the constituent atoms than to consider it as resulting from construction by means of elements with no consciousness. “Life,” says Haeckel, “is universal; we could not conceive of its existence in certain aggregates of matter if it did not belong to their constituent elements.” Here the postulate is almost expressed.