In regard to international relations, the first business of the teacher of economic theory is to tear to pieces and trample upon the misleading military metaphors which have been applied by sociologists to the peaceful exchange of commodities. We hear much, for example, in these days of “England’s commercial supremacy,” and of other nations “challenging” it, and how it is our duty to “repel the attack,” and so on. The economist asks “what is commercial supremacy?” and there is no answer. No one knows what it means, least of all those who talk most about it. Is it selling goods dear? Is it selling them cheap? Is it selling a large quantity of goods in proportion to the area of the country? Or in proportion to its area or population? Or absolutely, without any reference to its area or population? It seems to be a wonderful muddle of these various and often contradictory ideas rolled into one. Yet what a pile of international jealousy and ill-feeling rests on that and equally meaningless phrases! The teacher of economic theory analyzes or attempts to analyze these phrases, and they disappear, and with them go the jealousies suggested by them.