beings—a trace, as it were, of their sensibility. To them reactions of matter indicate the existence of a kind of hedonic consciousness—i.e., a consciousness reduced simply to a distinction between comfort and discomfort, a desire for good and repulsion from evil, which they suppose to be the universal principle of all activity. This was the view held by Empedocles in antiquity; it was that of Diderot, of Cabanis, and, in general, of the modern materialistic school, eager to find, even in the lowest representatives of the inorganic world, the first traces of the vitality and intellectual life which blossom out at the top of the scale in the living world.
Similar ideas are clearly seen in the early history of all natural sciences. It was this same principle of appetition, or of love and of repulsion or hate that, under the names of affinity, selection, and incompatibility, was thought to direct the transformations of bodies when chemistry first began; when Boerhaave, for example, compared chemical combinations to voluntary and conscious alliances, in which the respective elements, drawn together by sympathy, contracted appropriate marriages.
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
