‘It is impossible not to see in Mr. Russell’s work elements of real originality and great power of argument...’ Bertrand Russell’s study of the philosopher and mathematician Gottfried Leibniz is one of his earliest books, providing a fascinating glimpse of his philosophical brilliance. It remains one of the most important books on this polymathic seventeenth-century thinker and the only book Russell wrote about a major philosopher. Written when Russell was only in his late twenties, it goes far beyond a mere exposition of Leibniz’s thought. Celebrated for his invention of the differential calculus and a major figure in the development of rationalist philosophy, Leibniz is hailed by many as the last universal genius. Russell argues that the tension between Leibniz’s theological writings for the Hanoverian royalty on the one hand and his philosophical work on the other obscures, in Russell’s opinion, Leibniz’s greatest gift to philosophy: the view that logic is the start of all philosophy. Exploring Leibniz’s contributions to epistemology, substance, space and time, the soul and body, and the existence of God, Russell pushes philosophy and logical thought in bold new directions. It remains a vital work in Russell’s oeuvre and a landmark study of a major philosopher. This Routledge Classics Edition has a new Foreword by Richard T. W. Arthur.