For thousands of years nations and races became increasingly unlike until within the memory of living men, when this time-long stream of tendency, having accomplished its work, was reversed; and now, for nearly a century, there has been an increasing tendency toward oneness—the coördination and integration of different peoples into one great world life. This new tendency was caused by the application of steam to transportation by land and sea. In the first stage of international commerce transportation by caravans and row boats was so costly that only luxuries, such as gems, precious spices, and silks, were articles of commerce. This concerned only the few. The second stage was introduced by the application of sails and the discovery of the mariner’s compass, which made it possible to transport many of the conveniences of life, which affected increasing numbers. The third, and present, great stage of commerce began when railways brought the produce of continents to the seaboard, and the triple expansion engine made great merchant vessels possible. As a result, the necessaries of life are now transported in immense quantities, which fact vitally affects the entire people. These conditions have created an interdependence of the nations from which there is no escape. If a nation is agricultural, it is dependent on others, both for markets and for manufactures; if it is a manufacturing nation, it is dependent on others, both for markets and for food. When an agricultural people attempt to make themselves independent of other nations by establishing their own manufactures, they soon discover that by a sort of _mechanical Malthusianism_ machinery inevitably increases several times as fast as population; hence the nation no sooner becomes independent of those who wish to sell than it becomes dependent on those who wish to buy. The only possible way to avoid such national interdependence is to adjure modern civilization. The differentiation and organization of a world industry, which necessitates an ever-increasing international dependence, has created this new world life. In earlier ages, when nations were economically independent, political independence was natural and inevitable. Of course there could be no world-consciousness when a common world life did not exist, and each sovereign nation was sufficient unto itself. But as the world’s economic life becomes more nearly one—as it certainly will under the quiet compulsion of economic law—the increasing interdependence of nations places the well-being of each increasingly in the keeping of others; and their relations to each other become more and more vital until their mutual service becomes a matter of life and death. If, for instance, all other peoples should make and enforce a declaration of non-intercourse with Great Britain, that nation would literally perish in a few months.