RENE DESCARTES (1596-1650) From the Publisher's Preface. The present volume contains a reprint of the preface and the first part of the Principles of Philosophy, together with selections from the second, third and fourth parts of that work, corresponding to the extracts in the French edition of Gamier, are also given, as well as an appendix containing part of Descartes' reply to the Second Objections (viz., his formal demonstrations of the existence of Deity). The translation is based on the ori

Sir,—The version of my principles which you have been at pains to make, is so elegant and finished as to lead me to expect that the work will be more generally read in French than in Latin, and better understood. The only apprehension I entertain is lest the title should deter some who have not been brought up to letters, or with whom philosophy is in bad repute, because the kind they were taught has proved unsatisfactory; and this makes me think that it will be useful to add a preface to it for

I. THAT in order to seek truth, it is necessary once in the course of our life, to doubt, as far as possible, of all things. As we were at one time children, and as we formed various judgments regarding the objects presented to our senses, when as yet we had not the entire use of our reason, numerous prejudices stand in the way of our arriving at the knowledge of truth; and of these it seems impossible for us to rid ourselves, unless we undertake, once in our lifetime, to doubt of all those thin

I. That we cannot think too highly of the works of God. Having now ascertained certain principles of material things, which were sought, not by the prejudices of the senses, but by the light of reason, and which thus possess so great evidence that we cannot doubt of their truth, it remains for us to consider whether from these alone we can deduce the explication of all the phenomena of nature. We will commence with those phenomena that are of the greatest generality, and upon which the others de

CLXXXVIII. Of what is to be borrowed from disquisitions on animals and man to advance the knowledge of material objects. I should add nothing farther to this the Fourth Part of the Principles of Philosophy, did I purpose carrying out my original design of writing a Fifth and Sixth Part, the one treating of things possessed of life, that is, animals and plants, and the other of man. But because I have not yet acquired sufficient knowledge of all the matters of which I should desire to treat in th