The historical view of systems that makes up the larger part of these volumes, itself the outcome of some of M. Renouvier's most original ideas, has enabled him, in his return from history to criticism and construction, to express these ideas with renewed force. Both as a history of philosophy from a clearly denned point of view, and as the latest statement of M. Renouvier's own philosophical position, the whole work is of the highest importance and interest.

The history of thought is viewed not as a series of approximations to a final doctrine which includes all truth in itself, but as a process in which antagonisms become more and more definite; till at length the theses and antitheses of the chief antinomies of philosophy are marked out into two coherent systems, opposed to one another in detail and as wholes. From the beginning of his philosophical studies, M. Renouvier tells us, he was struck with the inward presence of antinomies in the greater philosophical systems. He found that in a small number of systems, as in those of Nicholas of Cusa, Giordano Bruno and Hegel, the attempt was openly made to solve all antinomies by a denial of the applicability of the law of contradiction to real being; and for some time he was under the fascination of this idea, and himself tried to construct a philosophy that should reconcile all doctrines by combining their contradictory positions.