The Treatise on Tolerance on the Occasion of the Death of Jean Calas from the Judgment Rendered in Toulouse (Pieces Originales Concernant la Mort des Sieurs Calas det le Jugement rendu a Toulouse) is a work by French philosopher Voltaire, published in 1763, in which he calls for tolerance between religions, and targets religious fanaticism, especially that of the Jesuits (under whom Voltaire received his early education), indicting all superstitions surrounding religions.