Few periods in the history of human thought can rival in interest that of the second half of the nineteenth century in France. The discussion covers the principal problems with which man’s mind is occupied in modern times and presents these in a manner which is distinctly human and not merely national. This alone would give value to the study of such a period. There is, however, to be added the more striking fact that there is a complete “turning of the tide” manifested during these fifty years in the attitude to most of the problems. Beginning with an overweening confidence in science and a belief in determinism and in a destined progress, the century closed with a complete reversal of these conceptions. Materialism and naturalism are both recognised as inadequate, a reaction sets in against positivism and culminates in the triumph of spiritualism or idealism. This idealism is free from the cruder aspects of the Kantian or Hegelian philosophy. The Thing-in-itself and the Absolute are abandoned; relativity is proclaimed in knowledge, and freedom in the world of action. Thoughts or ideas show themselves as forces operating in the evolution of history. This is maintained in opposition to the Marxian doctrine of the purely economic or materialistic determination of history. A marked tendency, however, is manifested to regard all problems from a social stand point. The dogmatic confidence in science gives way to a more philosophical attitude, while the conflict of science and religion resolves itself into a decay of dogma and the conception of a free religion. We have indicated the problem presented by “_science et conscience_,” and in so far as we have laid down any thesis or argument in these pages, as distinct from an historical account of the development, that thesis has been, that the central problem in the period was that of freedom. It was to this point which the consideration of science, or rather of the sciences, led us. We have observed the importance of the sciences for philosophy, and it is clear that, so far from presenting any real hostility to philosophy, it can acclaim their autonomy and freedom, without attempting by abstract methods to absorb them into itself. They are equally a concrete part of human thought, and in a deep and real sense a manifestation of the same spirit which animates philosophy.