162 THE WORLD AS WILL. BK. II.
of will, for every act of will at a particular time and in a particular place, upon which it must necessarily follow, under the presupposition of the character of the man. But no reason can ever he given that the man has this character; that he wills at all; that, of several motives, just this one and no other, or indeed that any motive at all, moves his will. That which in the case of man is the unfathomable character which is presupposed in every explanation of his actions from motives is, in the case of every unorganised body, its definitive quality — the mode of its action, the manifestations of which are occasioned by impressions from without, while it itself, on the contrary, is determined by nothing outside itself, and thus is also inexplicable. Its particular manifestations, through which alone it becomes visible, are subordinated to the principle of sufficient reason; it itself is groundless. This was in substance rightly understood by the schoolmen, who called it forma substantialis. (Cf. Suarez, Disput. Metaph., disp. xv. sect. 1.)
It is a greater and a commoner error that the phenomena which we best understand are those which are of most frequent occurrence, and which are most universal and simple; for, on the contrary, these are just the phenomena that we are most accustomed to see about us, and to be ignorant of. It is just as inexplicable to us that a stone should fall to the earth as that an animal should move itself. It has been supposed, as we have remarked above, that, starting from the most universal forces of nature (gravitation, cohesion, impenetrability), it was possible to explain from them the rarer forces, which only operate under a combination of circumstances (for example, chemical quality, electricity, magnetism), and, lastly, from these to understand the organism and the life of animals, and even the nature of human knowing and willing. Men resigned themselves without a word to starting from mere qualitates occulta, the elucidation of which was entirely given up, for they intended to build
