that the will is not conditioned by knowledge, as has hitherto been universally assumed, although knowledge is conditioned by the will.
Now this fundamental truth, which even to-day sounds so like a paradox, is the part of my doctrine to which, in all its chief points, the empirical sciences—themselves ever eager to steer clear of all Metaphysic—have contributed just as many confirmations forcibly elicited by the irresistible cogency of truth, but which are most surprising on account of the quarter whence they proceed; and although they have certainly come to light since the publication of my chief work, it has been quite independently of it as the years went on. Now, that it should be precisely this fundamental doctrine of mine which has thus met with confirmation, is advantageous in two respects. First, because it is the main thought upon which my system is founded; secondly, because it is the only part of my philosophy that admits of confirmation through sciences which are alien to, and independent of, it. For although the last seventeen years, during which I have been constantly occupied with this subject, have, it is true, brought me many corroborations as to other parts, such as Ethics, Aesthetics, Dianoiology; still these, by their very nature, pass at once from the sphere of actuality, whence they arise, to that of philosophy itself: so they cannot claim to be extraneous evidence, nor can they, as collected by me, have the same irrefragable, unequivocal cogency as those concerning Metaphysics proper which are given by its correlate Physics (in the wide sense of the word which the Ancients gave it). For, in pursuing its own road, Physics, i.e., Natural Science as a whole, must in all its branches finally come to a point where physical explanation ceases. Now this is precisely the Metaphysical, which Natural Science only apprehends as the impassable barrier at which it stops short and henceforth abandons its
