“If something cannot go on forever, it will stop.”
Congressional testimony in 1976, in reference to a then-current economic trend of rising international trade deficits.
Herb Stein's Unfamiliar Quotations http://www.slate.com/id/2561/
Quelle: A Symposium on the 40th Anniversary of the Joint Economic Committee, Hearings Before the Joint Economic Committee, Congress of the United States, Ninety-Ninth Congress, First Session; Panel Discussion: The Macroeconomics of Growth, Full Employment, and Price Stability, January 16, 1976, 262, I recently came to a remarkable conclusion which I commend to you and that is that if something cannot go on forever it will stop. So, what we have learned about all these things is that the Federal debt cannot rise forever relative to the GNP. Our foreign debt cannot rise forever relative to the GNP. But, of course, if they can't, they will stop., June 4, 2018 https://babel.hathitrust.org/cgi/pt?id=umn.319510030778307;view=1up;seq=270,