One of the greatest of modern philosophers, on a par with his contemporary John Locke, Leibniz was born in Leipzig in 1646, died in Hanover in 1716. He was a leading figure in European intellectual circles, and the founder of the Academy of Berlin. His strange, complex metaphysical system established him as the third of the great 'Rationalists', after Descartes and Spinoza. Along with the 'New System', his most famous philosophical works are the Discourse of Metaphysics (1685) and Monadology (c.1713). He also made important contributions to logic, mathematics, theology, jurisprudence, and history. Gathered here for the first time are all the key texts in a crucial debate in modern philosophy, centred on Leibniz's famous 1695 essay, the `New System of the Nature of Substances and their Communication'. In this classic essay Leibniz introduced to a broad European readership the strikingly original metaphysical ideas he had come to a decade earlier. His 'system' became increasingly famous and drew him into discussion and development of these ideas, both in public and in private, with a variety of thinkers: Simon Foucher; Henri Basbage de Beauval; Francois Lamy; Isaac Jacquelot; the Englishwoman Damaris Masham; Pierre Desmaizeaux; Rene Joseph de Tournemine; and most notably the great French philosopher and scholar Pierre Bayle.