An accessible guide to understanding many of the complex technical and special terms implemented by the seventeenth-century philosopher. French philosopher René Descartes authored many works in his lifetime like Discourse on the Method and Principles of Philosophy. But while his "I think, therefore I am" may be easy to grasp, much of the terminology he uses can be challenging. Descartes would frequently introduce terms in his writings without explanation, and if there were such a definition, it is in one of his letters or an obscure, unpublished work. In Descartes Dictionary, author John M. Morris collects as many as possible of the technical and special phrases Descartes employed in his writings along with their definitions in Descartes's own words. This volume is a great companion book for anyone studying the philosopher's works and will certainly enrich their understanding.