Gottfried Wilhelm Leibniz

German polymath, philosopher and mathematician who developed differential and integral calculus while in Paris between 1672 and 1676, independently of Isaac Newton's earlier but then-unpublished work. On 21 November 1675 Leibniz first wrote the integral sign, the elongated S still used today (from the Latin summa), and by autumn 1676 he had derived the power rule for differentiation; he published his method in 1684 (Nova Methodus pro Maximis et Minimis) and the integral sign first appeared in print in 1686. Leibniz's notation, not Newton's, is the one still taught. He also built one of the first mechanical calculating machines, the Stepped Reckoner, capable of all four arithmetic operations, and demonstrated an incomplete version to the Royal Society in London in January 1673. Beyond mathematics he made major contributions to logic, metaphysics (the theory of monads) and, in an idea centuries ahead of its practical use, the binary number system.