THE PRACTICAL ASPECT OF SCIENCE. But while the origins of science may lie in man's thirst for system, simplicity, and beauty in the world, the tremendous advance of science has a more immediate and practical cause. To understand the laws of Nature means to have the power of prediction; it means to know that, given certain circumstances, certain others follow always and inevitably; it means to discover causes--and their effects. Man having attained through patient inquiry this capacity to tell in advance, may take advantage of it for his own good. The whole of modern industry with its phenomenal control of natural powers and resources is testimony to the use which man has found for the facts and laws which he would never have found out save for the curiosity which was his endowment and the inquiry which he made his habit. "Knowledge is power," said Francis Bacon, and the three hundred years of science that have made possible the whole modern world of electric transportation, air travel between two continents, and instantaneous communication between remote parts of the world, have proved the aphorism. Man since his origin has tried to control his environment for his own good. The cave and the flint were his first rude attempts. In science with its accurate observation of facts not apparent to the unaided eye, and its discovery and demonstration of laws not found by casual and unsystematic common sense, man has an incomparably more refined instrument, and an incomparably more effective one. Thus, paradoxically enough, man's most disinterested and impartial activity is at the same time his most practical asset. THE CREATION OF BEAUTIFUL OBJECTS AND THE EXPRESSION OF IDEAS AND FEELINGS IN BEAUTIFUL FORM. Most men spend most of their lives necessarily in practical activity. Man's particular equipment of instincts survived in "the struggle for existence" precisely because they were practical, because they did help the human creature to maintain his equilibrium in a half-friendly, half-hostile environment. Man acquires also, as already has been pointed out, habits that are useful to him, that bring him satisfactions not attainable through the random instinctive responses which are his at birth. Reflection, too, is, for the most part, severely practical in its origins and its responsibilities. It guides action into economical and useful channels.