Simon had been Treasury Secretary for all of two months, and the government had a problem.

Three years earlier Nixon had cut the dollar loose from gold. Then came the Arab oil embargo, led by King Faisal of Saudi Arabia after the 1973 war, and the price of oil roughly quadrupled.

The real business was a four-day stop in Jeddah, where Simon's job was to talk the Saudis into financing America's deficits.

The deal was simple: Saudi Arabia plows its oil dollars into US government bonds, i.e. Treasuries, and in return America buys the oil, sells weapons to the Saudis, and guarantees the kingdom's security.

Faisal said yes, on one condition— nobody could know.

So the Treasury let the Saudis buy bonds in special sales that never showed up in the official totals.

It stayed secret for 41 years, until Bloomberg pried the numbers loose in 2016: the Saudis held $117 billion of US debt, and a former Treasury official said the real figure was probably double.

The part of the deal guaranteeing security was never written down, but everyone understood it. Jimmy Carter said it out loud in his 1980 State of the Union: any attempt by an outside force to control the Persian Gulf "will be repelled by any means necessary, including military force."

That was the deal, and it held for fifty years. It also meant Saudi oil would continue being sold exclusively in US dollars.

That forced the rest of the world to hold dollars, if only to buy oil from OPEC. Pretty much every country on the planet needs oil, so foreigners stockpiled US dollars… and, by extension, US government bonds.

As a result, the US government is able to get away with the fiscal equivalent of murder: $40 trillion in debt, more than the entire US economy produces in a year.