they seem to bring back the old controversies in a new form. But this does not alter the significance of the general fact; for, in the first place, the use of an idea by any writer is by no means always limited by his own interpretation of it; and, in the second place, the true interpretation of the idea is that which contains the secret of its power and prevalence, and it must in the long run gain the victory over all other interpretations of it. We may, therefore, fairly say that these ideas have been the marked ideas of the century, the conscious or unconscious stimulus of its best thought; and that they have been working, and are working still, in the direction of a deeper and more comprehensive irenicon between the different tendencies of the human mind than has been attained in any previous stage of the history of philosophy. Against such a general characterization of an age, there is the same objection which Burke indicated when he said that “he could not draw up an indictment against a nation.” We are taking a distant and general view of a period, in which all its inequalities of movement, all the ebb and flow of opinion, are lost sight of, and only one main current of thought is visible. We may get a step nearer to the subject by distinguishing three periods in the century, in which there is a partial difference of tendency. The first period, which we may roughly define as lasting well on into the 30’s, is, in the main, a period of construction, of creative thought, in which the great germinating ideas that distinguished the century are more or less adequately expressed in different countries, and in which they receive a first, somewhat hasty, application to all departments of human knowledge. Idealistic philosophy, which gave the fullest expression to those ideas, seems for a time to carry all before it in Germany; and a similar movement of thought, less definitely reflective or speculative, enriches the literature of other countries. In the next period, lasting until the 70’s, the new ideas do not lose their hold upon men’s minds, but there is a certain critical recoil against them, a tendency to explain them away. The first premature synthesis of idealistic philosophy is attacked by a scepticism, which seems at times as if it would measure back the whole way to the individualistic materialism of an earlier age, or which only avoids that extreme to fall into a scientific agnosticism, at first sight even more hostile to the claims of philosophy. But the lesson of Kant could never be altogether forgotten, nor could the negative or sceptical tendencies of the _Critique of Pure Reason_ be permanently separated from the positive results of his later writings. And the great scientific movement of the time, which at first seemed to draw away all interest from speculative inquiry, tended in the long run, especially by the advance of biological study, to raise metaphysical questions which the methods of science were incapable of answering.