<p>Principles of Philosophy is a book by Rene Descartes. It is basically a synthesis of the Discourse on Method and Meditations on First Philosophy.<br>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...