"THE naturalist conception of man has above all been influenced by the Darwinian doctrine of the Origin of Species, and by the evolutionary theories to which this gave rise. The doctrine of a continuous development through the whole of animate nature, and the gradual evolution of the human species under the influence of natural selection, seemed to show that no principle external to the material world need be invoked to account for man: he was of a piece with the rest of nature. Further, the theory of evolution was linked with the earlier liberal theories of political and social advance to form the modern doctrine of unlimited and inevitable material progress, a doctrine fundamentally unscientific and based on an irrational optimism, but which has nevertheless become a part of the mental furniture of the ordinary modern man. As yet, however, the naturalist movement has not received its definitive philosophy. There has been no lack of ambitious attempts to elaborate naturalistic syntheses, but none has been final. Neither Condorcet nor Holbach nor Bentham nor Comte nor Spencer nor Haeckel can be said to be the philosopher of the movement. Nevertheless, in their doctrine of man there is a large element common to all these philosophers. Whether they be Deists, Materialists, or Agnostics, they generally agree that man is a part of the material world; that in the knowledge, the control, and the enjoyment of this world he finds his true end, and that no spiritual principle can intervene in this closed order governed by uniform physical laws. Taking it as a whole, however, modern naturalism is due not so much to any philosophic theory, as to the material triumphs of modern civilization and man's conquest of nature. The realm of mystery before which man feels himself humble and weak has withdrawn its frontiers. Man can know his world without falling back on revelation; he can live his life without feeling his utter dependence on supernatural powers. He is no longer the servant of unknown forces, but a master in his own house, and he intends to make the most of his new-found powers."
~Christopher Dawson: The Nature and Destiny of Man.
