  It is an important question in the historiography of modern logic whether Leibniz’s logical calculi influenced logic in its present state or whether they were only ingenious anticipations. The most significant of Leibniz’s contributions to formal logic were published in the early 20th century. Only then, Leibniz’s logic could be fully understood. Nevertheless, the essentials of his philosophy of logic and some technical elaborations could be derived from early editions of his writings published in the 18th and 19th centuries.