This three-part work includes A Discourse on Method, Meditations on the First Philosophy, and Principles of Philosophy.By calling everything into doubt, Descartes laid the foundations of modern philosophy. With the celebrated words ';I think, therefore I am,' his compelling argument swept aside ancient and medieval traditions. He deduced that human beings consist of minds and bodies, that these are totally distinct ';substances,' and that God exists and that he ensures we can trust the evidence of our senses. Ushering in the ';scientific revolution' of Galileo and Newton, his ideas have set the agenda for debate ever since. His philosophical methods and investigation changed the course of Western philosophy and led to or transformed the fields of metaphysics, epistemology, physics, mathematics, political theory, and ethics.