_Apparent Heterogeneity is the Result of the Arrangement or the Combination of Homogeneous Bodies._—In this system, material energy, life, soul would only be more and more complex combinations of the consubstantial activity with material atoms. Life appears distinct from physical force, and thought from life, because the analysis has not yet advanced far enough. Thus, glass would appear to the ancient Chaldeans distinct from the sand and salt of which they made it. In the same way, again, water, to modern eyes, is distinct from its constituents, oxygen and hydrogen. The whole difficulty is that of explaining what this “arrangement” of the elements can introduce that is new in the aspect of the compound. We must know what novelty and apparent homogeneity the variety of the combinations, which are only special arrangements of the elementary parts, may produce in the phenomena. But we do not know, and it is this ignorance which leads us to consider them as heterogeneous, irreducible, and distinct in principle. The vital phenomenon, the complexus of physico-chemical facts, thus appears to us essentially different from those facts, and that is why we picture to ourselves “dominants” and “directing forces” more or less analogous to the sidereal guiding principle of Kepler, which, before the discovery of universal attraction, regulated the harmony of the movements of the planets. _A Reservation relative to the Psychical Order._—The scientific mind has shown in every age a real predilection towards the mechanical or materialistic theory. Contemporary scientists as a whole have accepted it in so far as it blends the vital and the physical orders. Objections and contradictions are only offered in the realm of psychology. A. Gautier, for example, has contested with infinite originality and vigour the claims of the materialists who would reduce the phenomenon of thought to a material phenomenon. The most general characteristic of material phenomenality is—as we shall later see—that it may be considered as a mutation of energy—_i.e._, it obeys the laws of energetics. Now thought, says A. Gautier, is not a form of material energy. Thought, comparison, volition, are not acts of material phenomenality; they are states. They are realities; they have no mass; they have no physical existence. They respond to adjustments, arrangements, and concerted groupings of material manifestations of chemical molecules. They escape the laws of energetics. _Kinetic Theory._—We shall lay aside for a moment this serious problem relative to the limits of the world of conscious thought and of the world of life. It is on the other side, on the frontiers of living and inanimate nature, that the mechanical view triumphs. It has furnished a universal conception agreeing with phenomena of every kind—viz., the kinetic theory, which ascribes everything in nature to the movements of particles, molecules, or atoms.