An attempt has been made in the following pages to present first a careful analysis of certain themes in Descartes’ moral doctrine.This is followed by a study of broader scope which examines Descartes’ philosophical posterity as represented by authors as different as Proudhon, Ravaisson, and Sartre.It is hoped that readers will find a measure of historical solidify in the first part and that they will not be unsympathetic with the second. The latter is an expression of personal adherence and involvement which can hardly require of the reader more than an assent that equally involves the risk of personal commitment. But as Descartes himself has observed and as the diffusion of his work has proved, history is a living and present enterprise that constructs the future.