The growth of industry and commerce is at once cause and effect of the growth in science. Democritus and other ancients conceived the mechanical theory of the universe. The notion was not only blank and repellent, because it ignored the rich social material which Plato and Aristotle had organized into their rival idealistic views; but it was scientifically sterile, a piece of dialectics. Contempt for machines as the accouterments of despised mechanics kept the mechanical conception aloof from these specific and controllable experiences which alone could fructify it. This conception, then, like the idealistic, was translated into a speculative cosmology and thrown like a vast net around the universe at large, as if to keep it from coming to pieces. It is from respect for the lever, the pulley, and the screw that modern experimental and mathematical mechanics derives itself. Motion, traced through the workings of a machine, was followed out into natural events and studied just as motion, not as a poor yet necessary device for realizing final causes. So studied, it was found to be available for new machines and new applications, which in creating new ends also promoted new wants, and thereby stimulated new activities, new discoveries, and new inventions. The recognition that natural energy can be systematically applied, through experimental observation, to the satisfaction and multiplication of concrete wants is doubtless the greatest single discovery ever imported into the life of man--save perhaps the discovery of language. Science, borrowing from industry, repaid the debt with interest, and has made the control of natural forces for the aims of life so inevitable that for the first time man is relieved from overhanging fear, with its wolflike scramble to possess and accumulate, and is freed to consider the more gracious question of securing to all an ample and liberal life. The industrial life had been condemned by Greek exaltation of abstract thought and by Greek contempt for labor, as representing the brute struggle of carnal appetite for its own satiety. The industrial movement, offspring of science, restored it to its central position in morals. When Adam Smith made economic activity the moving spring of man’s unremitting effort, from the cradle to the grave, to better his own lot, he recorded this change. And when he made sympathy the central spring in man’s conscious moral endeavor, he reported the effect which the increasing intercourse of men, due primarily to commerce, had in breaking down suspicion and jealousy and in liberating man’s kindlier impulses.