Denis Diderot (1713-1784) French Enlightenment era art critic, writer and philosopher who, from 1745 to 1772, served as chief editor of the Encyclopedie, one of the principal works of the Age of Enlightenment. As a dictionnaire raisonné (“rational dictionary”), the Encyclopedie was to bring out the essential principles and applications of every art and science. The underlying philosophy was rationalism and a qualified faith in the progress of the human mind.