Principles of Philosophy was written in Latin by René Descartes. Published in 1644, it was intended to replace Aristotle's philosophy and traditional Scholastic Philosophy. This volume contains a letter of the author to the French translator of the Principles of Philosophy serving for a Preface and a letter to the most serene princess, Elizabeth, eldest daughter of Frederick, King of Bohemia, Count Palatine, and Elector of the Sacred Roman Empire.