French mathematician and philosopher. Although he achieved his distinction as a mathematician, in philosophy d'Alembert is remembered as one of the greatest figures of the French Enlightenment. Together with Diderot he was the moving force behind the Encyclopédie. His own philosophy placed total faith in natural science, although like Locke before him he tempered his empiricism with confidence in a rational structure to both the natural and the ethical domain. There is some evidence that d'Alembert progressed from a tentative theism, based upon the distinct nature of intelligence and the impossibility of it emerging in a purely material universe, to an atheistic and materialist view of the world. There are many testimonies to his virtuous and philosophical character, and Hume entirely entrusted to him the conduct of his dispute with Rousseau.