Principles of Philosophy is a classic philosophy text by René Descartes. It is basically 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 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.