During this long period, however, the progress of human association made great and varied development. The gap between the men of Santander's caves, or early Egypt, and the civilization of a century ago is bridged rather by union of human powers, by the needs and stimulating contacts of society, than by conquest in the field of nature. It was in military, political, and religious organization that the power of associated effort was first shown. Army, state, and hierarchy were its visible representatives. Then, a little over a century ago, began what we call the industrial revolution, still incomplete, which combined new natural forces with new forms of human association. Steam, electricity, machines, the factory system, railroads: these suggest the natural forces at man's disposal; capital, credit, corporations, labor unions: these suggest the bringing together of men and their resources into units for exploiting or controlling the new natural forces. Sometimes resisting the political, military, or ecclesiastical forces which were earlier in the lead, sometimes mastering them, sometimes combining with them, economic organization has now taken its place in the world as a fourth great structure, or rather as a fourth great agency through which man achieves his greater tasks, and in so doing becomes conscious of hitherto unrealized powers. Early in this great process of social organization three divergent types emerged, which still contend for supremacy in the worlds of action and of valuation: dominance, competition, and coöperation. All mean a meeting of human forces. They rest respectively on power, rivalry, and sympathetic interchange. Each may contribute to human welfare. On the other hand, each may be taken so abstractly as to threaten human values. I hope to point out that the greatest of these is coöperation, and that it is largely the touchstone for the others.