Principles of Philosophy is a book by
René Descartes. In essence it is a synthesis of the
Discourse on Method and
Meditations on First Philosophy It was written in
Latin, published in 1644 and dedicated to
Elisabeth of Bohemia, with whom Descartes had a long-standing friendship. A French version (
Les Principes de la Philosophie) followed in 1647. It set forth the principles of nature—the
Laws of Physics—as Descartes viewed them. Most notably, it set forth the principle that in the absence of external forces, an object's motion will be uniform and in a straight line.
Newton borrowed this principle from Descartes and included it in his own
Principia; to this day, it is still generally referred to as
Newton's First Law of Motion. The book was primarily intended to replace the
Aristotelian curriculum then used in French and British Universities. The work provides a systematic statement of his
metaphysics and
natural philosophy, and represents the first truly comprehensive,
mechanistic account of the universe.