… is from page 2 of Harry Johnson’s October 5th, 1976, Woodward Court lecture at the University of Chicago, “The International Economic Order“:
[T]he idea that international trade is a zero-sum game by which the rich benefit at the expense of the poor goes back to the Marxist view of imperialism, and before that to the mercantilist idea that foreign trade is a means of transferring wealth from one’s customers to oneself and the main thrust of Adam Smith’s Wealth of Nations and of classical economics was to refute mercantilism.