Principles of Philosophy, a compilation of René Descartes’ later philosophical ideas, was first written in Latin and published in 1644. It was later translated into French by Claude Picot, dean of the monastery, and published in 1647.
This book mainly shows how Descartes, starting from the natural principles he derived through reflection, introduced step by step all natural phenomena, from the heavens to the earth. These natural principles echo the definite metaphysical principles that Descartes reached through epistemological skepticism in his Meditations on First Philosophy, and Descartes believes that they constitute the "roots" of the tree of philosophy. From these few root systems, one can grow the "giant tree" of physics, and differentiate "branches" such as medicine, mechanics, engineering, and ethics. The whole Principles of Philosophy is a detailed presentation of this process of growth or differentiation.