The Bastille held François-Marie Arouet twice within a decade. The first time, from May 1717 to April 1718, was for satirical verses accusing the Regent, France's ruler during the childhood of Louis XV, of incest with his own daughter; he came out calling himself Voltaire. The second time, in 1726, followed a quarrel with the chevalier de Rohan, a nobleman who had his servants beat Voltaire. When Voltaire tried to get satisfaction, he was the one locked up, and he won his release by asking to be sent to England instead.
He stayed about two and a half years, and England gave him his subject: a country that let its sects worship side by side, honoured its merchants and had produced Locke and Newton. The Philosophical Letters he made of it argue that a nation grows free, rich and reasonable when it tolerates belief, respects trade and follows evidence rather than authority. From then on, two convictions ran through everything he wrote: what we can know comes from experience and must be tested against it, and no church or state has the right to punish a person for what they believe. The book caused a scandal, much of it over the letter on Locke, which dwelt on Locke's suggestion that God might have given matter itself the power to think. On 10 June 1734 the Parlement of Paris, the kingdom's highest court, had the book burned by the executioner. By then Voltaire had already left Paris ahead of an arrest order.
He took refuge at Cirey, the château of Émilie du Châtelet, the mathematician who later translated Newton's Principia into French, and for fifteen years it was the base of their working partnership. His Éléments de la philosophie de Newton (1738) set out Newton's physics for French readers still loyal to Descartes, and made the same case as the Letters: a fact observed outweighs a system reasoned out in advance. Voltaire built no system of his own. He wrote plays, poems, histories and tales as often as treatises, and much of his philosophy is an attack on the systems of others.
Leibniz, the German philosopher, had argued that God chose the best of all possible worlds, so that every evil serves a larger good. On 1 November 1755 an earthquake destroyed Lisbon and killed tens of thousands. Voltaire answered first with a poem on the disaster and then, in 1759, with Candide, an unsigned comic tale that sends its hero through war, shipwreck, the earthquake itself and an auto-da-fé, the Inquisition's public punishment of heretics, while his tutor Pangloss goes on explaining that all is for the best. The tale offers no rival doctrine; it ends with its travellers on a small farm, working their garden.
The same year he bought the estate of Ferney, on the French side of the border with Geneva, and from the early 1760s it was his home. There philosophy became a campaign. On 10 March 1762 Jean Calas, a Protestant merchant of Toulouse, was broken on the wheel; he had been accused of killing his son to stop the young man becoming a Catholic. Voltaire at first believed the verdict, was persuaded otherwise by Calas's son Pierre, and wrote the Treatise on Tolerance for the men who governed France; in 1765 a royal tribunal declared Calas innocent.
His letters of these years repeat Écrasez l'infâme — crush the infamous thing — meaning the fanaticism and superstition he blamed on the churches. He kept a belief in one just God and a morality common to every people, and his Philosophical Dictionary (1764), which he denied writing, treated scripture as a document like any other and weighed its miracles and chronology against what any reader knows of the world. In 1766 a copy was thrown onto the pyre of the chevalier de La Barre, a young nobleman executed at Abbeville for impiety.
In February 1778, at eighty-three, Voltaire returned to Paris for the first time in more than twenty-five years, and died there on 30 May. Refused a Christian burial in Paris, he was buried secretly at the abbey of Scellières in Champagne. On 11 July 1791 the National Assembly, which counted him a forerunner of the Revolution, had his remains carried to the Panthéon. Philosophers long treated him as a campaigning writer rather than a thinker, and his place in the history of philosophy is still argued over. In 2015, after the attack on the satirical weekly Charlie Hebdo, the Treatise on Tolerance sold some 185,000 copies in France.