Paul O’Neill, a former U.S. Treasury secretary, said that if America ever dropped the strong-dollar policy, he would hire a brass band at Yankee Stadium to mark the proclamation.

O’Neill had reservations about the mantra, but ultimately fell into line. The musicians didn’t make it to rehearsal on his watch and Washington's support for greenback primacy lived on, with the odd tweak every now and then.

Challenges to the dollar’s vital role in the world economic and financial system are often said to be, if not imminent, then over the horizon. But somehow they never quite materialize. Don’t expect any of the current noise about movement toward a currency shared by the BRICS nations — Brazil, Russia, India, China and South Africa — to amount to much. If any of these were to be the foundation of a single unit of exchange, it would likely be China. Precedent isn't encouraging: Seven years after the International Monetary Fund added the yuan to its basket of reserve currencies, it accounts for a very minute share of the global cache.