Jacobi Friedrich Heinrich (1743–1819), German man of letters, popular novelist, and author of several influential philosophical works. His Ueber die Lehre des Spinoza (1785) precipitated a dispute with Mendelssohn on Lessing’s alleged pantheism. The ensuing Pantheismusstreit (pantheism controversy) focused attention on the apparent conflict between human freedom and any systematic, philosophical interpretation of reality. In the appendix to his David Hume über den Glauben, oder Idealismus und Realismus (‘David Hume on Belief, or Idealism and Realism,’ 1787), Jacobi scrutinized the new transcendental philosophy of Kant, and subjected Kant’s remarks concerning ‘things-in-themselves’ to devastating criticism, observing that, though one could not enter the critical philosophy without presupposing the existence of things-in-themselves, such a belief is incompatible with the tenets of that philosophy. This criticism deeply influenced the efforts of post-Kantians (e.g., Fichte) to improve transcendental idealism. In 1799, in an ‘open letter’ to Fichte, Jacobi criticized philosophy in general and transcendental idealism in particular as ‘nihilism.’ Jacobi espoused a fideistic variety of direct realism and characterized his own standpoint as one of ‘nonknowing.’ Employing the arguments of ‘Humean skepticism,’ he defended the necessity of a ‘leap of faith,’ not merely in morality and religion, but in every area of human life. Jacobi’s criticisms of reason and of science profoundly influenced German Romanticism. Near the end of his career he entered bitter public controversies with Hegel and Schelling concerning the relationship between faith and knowledge. See also KANT. D.Br.