This unique collection of background material to Descartes' Meditations has been translated from the original French and Latin. The texts gathered here illustrate the kinds of principles, assumptions, and philosophical methods that were commonplace when Descartes was growing up. The selections are from Francisco Sanches, Christopher Clavius, Pierre de la Rameé (Petrus Ramus), Francisco Suarez, Pierre Charron, Eustachius a Sancto Paulo, Scipion Dupleix, Marin Mersenne, Pierre Gassendi, François de la Mother le Vayer, Charles Sorel, and Jean-Baptiste Morin.