This study explores the problems faced by writers of the Enlightenment, who attempted to demystify all previous forms of knowledge by applying rationalist critiques that can in turn be applied to examine their own critical work. It focuses on the works of one of the best-known writers of eighteenth-century France, Denis Diderot, analysing his experimentation with presenting critical knowledge. Paying close attention to the formal-poetic nature of Diderot's writing, his 'art', it examines the interplay between critical knowledge and its representation, between epistemology and aesthetics. Professor Brewer shows how Diderot's work in the areas of philosophy, science, the fine arts and literature pushed Enlightenment critique to its limits, and points to its remarkable similarity to aspects of modern critical theory.