IV. The World as Perception

But even less can the thesis, “ The perceived world is my mental picture,” be presented as obvious in itself and needing no proof. Schopenhauer begins his principal work, The World as Will and Mental Picture,[^6] with the word: “The world is my mental picture:—this is the truth which is valid with respect to every living and knowing being, even though man alone can bring it into reflective abstract consciousness; and if he really does this, then philosophical enlightenment has occurred for him. It will then become definite and certain for him that he knows no sun and no earth, but always only an eye that sees the sun, a hand that feels the earth; that the world which surrounds him is there only as mental picture, i.e., that it absolutely is there only in relationship to something else, to the one doing the mental picturing, which he himself is.—If ever a truth could be declared a priori, it is this one; for it is the expression of that form which every possible and imaginable experience has, that form which is more general than all others, such as time, space and causality; for all these already presuppose the first form ...” This whole thesis founders upon the fact I have already indicated above, that the eye and the hand are no less perceptions than the sun and the earth. And one could, in Schopenhauer's sense and in his own terms, confront his thesis with: My eye that sees the sun, and my hand that feels the earth are my mental pictures in just the same way as the sun and earth themselves are. That I thereby invalidate his thesis, however, is immediately clear. For only my real eye and my real hand could have, connected to them as their own modifications, the mental pictures sun and earth; my mental pictures of eye and hand could not however have these mental pictures. But only of these can critical idealism speak.