Thinker and essayist. In addition to contributing to mathematics and physics, he assisted Diderot with the scientific sections of the Encyclopedia, the central text of the French Enlightenment, and had the honor of authoring its introductory essay. As a passionate believer in the ideas of the Enlightenment, he excoriated superstition in all its forms, which in his view included religion and all social institutions and authorities, whether Church, family, or state, that sought to control and limit freedom of thought, inquiry, discovery, or speech.