Voltaire and the Enlightenment Critique of Religious Fanaticism

François-Marie Arouet, known to history as Voltaire, became the most influential — and most controversial — figure of the French Enlightenment. He introduced Newton's and Locke's ideas to France in his "Philosophical Letters" (1734), also known as the "English Letters," and he spent his career systematically defending religious tolerance against the fanaticism and intolerance of ecclesiastical institutions. His 1763 "Treatise on Tolerance" grew directly out of his public defense of Jean Calas, a Protestant wrongly convicted of murdering his own son to prevent his conversion to Catholicism and then executed; Voltaire's campaign on Calas's behalf turned the case into an international symbol of religious injustice, and he pursued a similar defense in the Sirven case and other unjust trials.