Paul-Henri Thiry, Baron d’Holbach (1723–1789) was a German-born, French-naturalized philosopher whose Paris salon hosted Diderot, Hume, Adam Smith and Benjamin Franklin. A contributor to the Encyclopédie, he became the most uncompromising atheist and materialist of the Enlightenment, author of the Système de la nature (1770). He published his anticlerical works — including the satirical Théologie portative — anonymously or under borrowed names to evade censorship, which is partly why his sharpest lines drift to more famous signatures like Voltaire’s.