The eighteen lectures that compose this volume have in fact the particular trait that, if the history of philosophy furnishes their frame-work, philosophy itself occupies in them the first place, and that, instead of researches of erudition and criticism, they present a regular exposition of the doctrine which was at first fixed in our mind, which has not ceased to preside over our labors. This book, then, contains the abridged but exact expression of our convictions on the fundamental points of philosophic science. In it will be openly seen the method that is the soul of our enterprise, our principles, our processes, our results.