THE OBJECTIFICATION OF THE WILL. 125
botany and zoology, the various permanent, organised, and therefore definitely determined forms in the constant change of individuals; and these forms constitute a great part of the content of the idea of perception. In natural history they are classified, separated, united, arranged according to natural and artificial systems, and brought under concepts which make a general view and knowledge of the whole of them possible. Further, an infinitely fine analogy both in the whole and in the parts of these forms, and running through them all (unité de plan), is established, and thus they may be compared to innumerable variations on a theme which is not given. The passage of matter into these forms, that is to say, the origin of individuals, is not a special part of natural science, for every individual springs from its like by generation, which is everywhere equally mysterious, and has as yet evaded definite knowledge. The little that is known on the subject finds its place in physiology, which belongs to that part of natural science I have called etiology. Mineralogy also, especially where it becomes geology, inclines towards etiology, though it principally belongs to morphology. Etiology proper comprehends all those branches of natural science in which the chief concern is the knowledge of cause and effect. The sciences teach how, according to an invariable rule, one condition of matter is necessarily followed by a certain other condition; how one change necessarily conditions and brings about a certain other change; this sort of teaching is called explanation. The principal sciences in this department are mechanics, physics, chemistry, and physiology.
If, however, we surrender ourselves to its teaching, we soon become convinced that etiology cannot afford us the information we chiefly desire, any more than morphology. The latter presents to us innumerable and infinitely varied forms, which are yet related by an unmistakable family likeness. These are for us ideas, and when only treated in this way, they remain always strange to us,
