Principia could refer to:*Philosophiae Naturalis Principia Mathematica, Isaac Newton's three-volume work containing explanations of his laws of motion and his law of universal gravitation Principia philosophiae, a major work by René Descartes Principia Mathematica, Alfred North Whitehead and Bertrand Russell's axiomatic work on mathematics Principia Ethica, a seminal work in metaethics by G. E. Moore Principia Discordia, a major holy book in Discordianism The Principia, a Christian Scie… (More on Principia)