By denying the idea of an unprejudiced and presuppositionless reason and his assertion of a fundamental belief that underlies every performance of reason, Jacobi provoked both the German Enlighteners and the representatives of German Idealism. The paper tries to demonstrate the systematic importance of this provocation. To this end, it emphasizes Jacobi’s anticipation of Fichte’s and Schelling’s distinction between a negative (purely rational) and a positive philosophy. In particular, this study focuses on the idea of the self-annihilation of pure reason (...) in its consequent self-realization. (shrink)