What are the teachings of René Descartes?

René Descartes is best known for his contributions to philosophy and mathematics, particularly his method of doubt and the famous dictum "Cogito, ergo sum" ("I think, therefore I am"). He emphasized the importance of reason and skepticism in acquiring knowledge, advocating for a systematic approach to doubt and inquiry. Descartes also made significant strides in developing Cartesian geometry, linking algebra and geometry, which laid the groundwork for modern calculus. His dualistic view of the mind and body further influenced discussions in metaphysics and the philosophy of mind.