But in fact, what happened over three days and four nights in May 2010 is essential to understanding the economic predicament in which the world still finds itself. In that moment, the major Western central banks — and their leaders, Ben S. Bernanke of the U.S. Federal Reserve, Mervyn King of the Bank of England, and Trichet of the ECB — made a series of decisions that created the world economy we inhabit today, and likely far into the future.

Through half a decade of crisis that spanned every continent on Earth, it was this triumvirate of central bankers who responded on a scale and with a speed that presidents and parliaments could never muster. They deployed trillions of dollars, pounds and euros, often in concert, always trying to contain the damage. They made plenty of mistakes, some of them costly. But they also have kept the world from a disastrous economic collapse of the sort their predecessors had allowed eight decades earlier, setting the stage for the rise of the Nazis and World War II.