Rene Descartes

Selections from the Principles of Philosophy Rene Descartes

Descartes intended the Principles of Philosophy to be his magnum opus, the synthesis of all his theories in physics and philosophy. The book, therefore, is full of information, but it is conveniently divided up into four easily digestible parts. Each of the parts is constructed as a collection of logically connected principles, conveniently numbered and titled. Part I is the only section of the book that we, today, would call "philosophy." It is an account of Descartes' epistemology and his metaphysics. The rest of the book, beginning with Part II, deals with Descartes' natural philosophy, or what we would call "science." Descartes lays out the principles of his physics in Part II. In Part III he uses these principles to develop his theory of the structure of the universe and the solar system. Part IV uses these same principles to investigate the origins of the earth as well as a wide variety of earthly phenomena. The book concludes with bits and pieces of a theory of physiology and psychology.