Voltaire (1694-1778), French author. Best known for his book Elemens de la Philosophie de Neuton (1738). This was a guide to the theories of Isaac Newton's less accessible Principia Mathematica (1687). Although known as Voltaire, his real name was Francois Marie Arouet. Voltaire was also a fearless campaigner against injustice. During his life he was exiled from France and even imprisoned in the Bastille.