  Polemicist, socialite, and literary figure, Friedrich Jacobi (b. 1743, d. 1819) was an outspoken critic, first of the rationalism of German late Enlightenment philosophy, then of Kant’s Transcendental Idealism, especially in the form that the early Fichte gave to it, and finally of the Romantic Idealism of the late Schelling. In all cases, his opposition to the philosophers was based on his belief that their passion for explanation unwittingly led them to confuse conditions of conceptualization with conditions of existence, thereby denying all room for individual freedom or for a personal God. Jacobi made this point, in defence of individualism and personalistic values, in a number of public controversies, in the course of which he put in circulation expressions and themes that resonate to this day. He was the one who invited Lessing, who he thought was walking on his head in the manner of all philosophers, to perform a salto mortale (a jump heels over head) that would redress his position and thus allow him to move again on the ground of common sense. He was also responsible for forging the concept of ‘nihilism’ — a condition of which he accused the philosophers — and thereby initiating the discourse associated with it. His battle cry, which he first directed at the defenders of Enlightenment rationalism and then at Kant and his successors, was that ‘consistent philosophy is Spinozist, hence pantheist, fatalist and atheist’. The formula had the effect of bringing Spinoza to the centre of the philosophical discussion of the day. In the face Kant and his idealistic successors, Jacobi complained that they had subverted the language of the ‘I’ by reintroducing it on the basis of abstractions that in fact negated its original value. They had thus replaced real selfhood with the mere illusion of one.