[229] physical world has been gradually supplanted by the theory of energy, and Ostwald, who was one of the foremost exponents of energy, has made it a leading idea of Monism. What has been called matter is, so far as we know now, simply a complex of energies, and he has sought to extend the “energetic” principle from physical or chemical to biological, psychical, and social phenomena. But it is to be observed that no finality is claimed for the conception of energy; it is simply an hypothesis which corresponds to our present stage of knowledge, and may, as knowledge advances, be superseded. Monism resembles the positive philosophy and religion of Comte in so far as it means an outlook on life based entirely on science and excluding theology, mysticism, and metaphysics. It may be called a religion, if we adopt Mr. MacTaggart’s definition of religion as “an emotion resting on a conviction of the harmony between ourselves and the universe at large.” But it is much better not to use the word religion in connexion with it, and the Monists have no thought of finding a Monistic, as Comte founded a Positivist, church. They insist upon the sharp opposition between the outlook of science and the outlook of religion, and find the mark of spiritual progress in the fact that religion is [230] gradually becoming less indispensable. The further we go back in the past, the more valuable is religion as an element in civilization; as we advance, it retreats more and more into the background, to be replaced by science. Religions have been, in principle, pessimistic, so far as the present world is concerned; Monism is, in principle, optimistic, for it recognizes that the process of his evolution has overcome, in increasing measure, the bad element in man, and will go on overcoming it still more. Monism proclaims that development and progress are the practical principles of human conduct, while the Churches, especially the Catholic Church, have been steadily conservative, and though they have been unable to put a stop to progress have endeavoured to suppress its symptoms—to bottle up the steam. [6] The Monistic congress at Hamburg in 1911 had a success which surprised its promoters. The movement bids fair to be a powerful influence in diffusing rationalistic thought. [7] If we take the three large States of