The phenomena of nature are a system of things which co-exist and follow each other according to invariable laws. This deadly proposition was asserted early in the nineteenth century to be an axiom of science. It was formulated by Mill (in his System of Logic, 1843) as the foundation on which scientific induction rests. It means that at any moment the state of the whole universe is the effect of its state at the preceding moment; the casual sequence between two successive states is not broken by any arbitrary interference suppressing or altering the relation between cause and effect. Some ancient Greek philosophers were convinced of this principle; the work done by modern science in every field seems to be a verification of it. But it need not be stated in such an absolute form. Recently, scientific men have been inclined to express the axiom with more reserve and less dogmatically. They are prepared to recognize that it is simply a postulate without which the scientific comprehension of the universe would be impossible, and they are inclined to state it not as a law of causation—for the idea of causation leads into metaphysics—but rather as uniformity of experience. But they are not [184] readier to admit exceptions to this uniformity than their predecessors were to admit exceptions to the law of causation. The idea of development has been applied not only to nature, but to the mind of man and to the history of civilization, including thought and religion. The first who attempted to apply this idea methodically to the whole universe was not a student of natural science, but a metaphysician, Hegel. His extremely difficult philosophy had such a wide influence on thought that a few words must be said about its tendency. He conceived the whole of existence as what he called the Absolute Idea, which is not in space or time and is compelled by the laws of its being to manifest itself in the process of the world, first externalizing itself in nature, and then becoming conscious of itself as spirit in individual minds. His system is hence called Absolute Idealism. The attraction which it exercised has probably been in great measure due to the fact that it was in harmony with nineteenth-century thought, in so far as it conceived the process of the world, both in nature and spirit, as a necessary development from lower to higher stages. In this respect indeed Hegel’s vision was limited. He treats the process as if it were practically complete already, and does not take into account