Virtue supposes liberty, as the carrying of a burden supposes active force. Under coercion there is no virtue, and without virtue there is no religion. Make a slave of me, and I shall be no better for it. Even the sovereign has no right to use coercion to lead men to religion, which by its nature supposes choice and liberty. My thought is no more subject to authority than is sickness or health.

Questions sur l'Encyclopédie (1770–1774)