  It seems to be in accord with the second position that the pioneers of modern logic themselves referred to Leibniz. George Boole’s widow, Mary Everest Boole, e.g., wrote that her husband, having been informed of Leibniz’s anticipations of his own logic, felt “as if Leibnitz had come and shaken hands with him across the centuries” (M. E. Boole 1905, quoted in Laita 1976, 243). William Stanley Jevons, who was responsible for the great public success of modern logic in Great Britain after Boole, claimed that “Leibnitz’ logical tracts are […] evidence of his wonderful sagacity” (Jevons 1883 [1874], xix). Ernst Schröder thought that Leibniz’s ideal of a logical calculus had been brought to perfection by George Boole (Schröder 1877, III). The special controversy between Ernst Schröder and Gottlob Frege which was at the root of the later distinction between two kinds of modern logic, the algebra of logic and the Frege-style mathematical logic, was centered on the question how far the Leibnizian heritage was present in the respective variations of logic. In his Begriffsschrift, Frege had written that the idea of a general characteristic, of a calculus philosophicus or ratiocinator was too ambitious to be achieved by Leibniz alone. Frege’s own Begriffsschrift provides the first steps towards this goal, which can be found in the formula languages of arithmetic and chemistry (Frege 1879, VI). In his review of Frege’s Begriffsschrift, Schröder (Schröder 1880, 82) objected that the title “Begriffsschrift” promises too much. According to Schröder, Frege’s system is less of a ‘general characteristic’ and more of a calculus ratiocinator, and its development would have been significant, had it not already been achieved by others (esp. by Boole). Frege replied (Frege 1883, 1) that he did not intend to present an abstract logic in formulae like Boole, but to express contents by written signs in a more precise and clear manner than it would be possible by words. Therefore the Begriffsschrift is not a mere calculus ratiocinator, but a lingua characteristica in the Leibnizian sense, although he accepted that inferential calculation (schlussfolgernde Rechnung) was a necessary constituent of the Begriffsschrift.