In 2006, Ben S. Bernanke was appointed chair of the Federal Reserve, the unexpected apex of a personal journey from small-town South Carolina to prestigious academic appointments and finally public service in Washington's halls of power.

There would be no time to celebrate.

The bursting of a housing bubble in 2007 exposed the hidden vulnerabilities of the global financial system, bringing it to the brink of meltdown. From the implosion of the investment bank Bear Stearns to the unprecedented bailout of insurance giant AIG, efforts to arrest the financial contagion consumed...