started. Therefore also, in the case of the important fundamental knowledge here considered, one must not merely go from the intellect to the knowledge of the world, as Kant has done, but also from the world, taken as given, to the intellect, as I have undertaken here. Then this physiological consideration, in the wider sense, becomes the supplement of that ideological, as the French say, or, more accurately, transcendental consideration.
In the above, in order not to break the thread of the exposition, I have postponed the explanation of one point which I touched upon. It was this, that in proportion as, in the ascending series of animals, the intellect appears ever more developed and complete, knowledge always separates itself more distinctly from will, and thereby becomes purer. What is essential upon this point will be found in my work, "Ueber den Willen in der Natur," under the heading, "Pflanzenphysiologie" (p. 68-72 of the second, and 74-77 of the third edition), to which I refer, in order to avoid repetition, and merely add here a few remarks. Since the plant possesses neither irritability nor sensibility, but the will objectifies itself in it only as plastic or reproductive power, it has neither muscle nor nerve. In the lowest grades of the animal kingdom, in zoophites, especially in polyps, we cannot as yet distinctly recognise the separation of these two constituent parts, but still we assume their existence, though in a state of fusion; because we perceive movements which follow, not, as in the case of plants, upon mere stimuli, but upon motives, i.e., in consequence of a certain apprehension. Now in proportion as, in the ascending series of animals, the nervous and muscular systems separate ever more distinctly from each other, till in the vertebrate animals, and most completely in man, the former divides into an organic and a cerebral nervous system, and of these the latter again develops into the excessively complicated apparatus of the cerebrum and cerebellum, spinal marrow, cerebral and spinal nerves, sensory and motor nerve fascicles, of which only
