received impressions of sense a reaction even takes place, which does not proceed directly from the will, but is primarily a spontaneity of the function of understanding, which makes the transition from the directly perceived sensation of the senses to its cause; and since the brain then at once produces the form of space, there thus arises the perception of an external object. We may therefore regard the point at which the understanding makes the transition from the mere sensation upon the retina, which is still a mere affection of the body and therefore of the will, to the cause of that sensation, which it projects by means of its form of space, as something external and different from its own body, as the boundary between the world as will and the world as idea, or as the birthplace of the latter. In man, however, the spontaneity of the activity of the brain, which in the last instance is certainly conferred by the will, goes further than mere perception and immediate comprehension of causal relations. It extends to the construction of abstract conceptions out of these perceptions, and to operating with these conceptions, i.e., to thinking, as that in which his reason consists. Thoughts are therefore furthest removed from the affections of the body, which, since the body is the objectification of the will, may, through increased intensity, pass at once into pain, even in the organs of sense. Accordingly idea and thought may also be regarded as the efflorescence of the will, because they spring from the highest perfection and development of the organism; but the organism, in itself and apart from the idea, is the will. Of course, in my explanation, the existence of the body presupposes the world of idea; inasmuch as it also, as body or real object, is only in this world; and, on the other hand, the idea itself just as much presupposes the body, for it arises only through the function of an organ of the body. That which lies at the foundation of the whole phenomenon, that in it which alone has being in itself and is original, is exclusively the will; for it is the
