… is from pages 484-485 of volume 2 of The Collected Works of Armen A. Alchian (2006); specifically, it’s from Alchian‘s 1982 address (“Customs, Behavior, and Property Rights”) to the Peking Institute of Foreign Trade:
[A]s Chinese trade expands with the United States, American politicians will complain that you are selling us more than we are selling to you. You should ignore our American politicians, who don’t know that international trade involves many countries. No one buys from another exactly the same amount sold. Instead, three- or four- or five-way trade – called multilateral trade – occurs, and one country’s imbalance with another country is matched by its opposite balance with still another. But some politicians who understand that fact are really representing some American producers who are being displaced by the foreign imports. We American consumers welcome those imports.
