Nearly a decade ago, President Barack Obama gathered top members of his economic team at the White House to announce his most aggressive response to the financial crisis to date. No longer, Obama declared, would big banks be allowed to put taxpayer money at risk to orchestrate proprietary trading operations for their own profit.

The press conference was designed to signal an ideological left turn. Jackie Calmes at The New York Times described the administration throwing a public punch at Wall Street in order to strike a more populist tone. The Washington Post ruminated about a power shift away from finance-friendly Obama confidants Larry Summers and Timothy Geithner toward legendary former Federal Reserve Chairman Paul Volcker.

Obama himself put it bluntly: Were about to get into a big fight with the banks.

It was a moment knotted with paradox and irony. Volcker a titan of the American financial establishment, a friend to billionaires and CEOs around the world was championing what would prove to be the most radical economic initiative of the Obama era.

The financial crisis of 2008 had exposed proprietary trading as a source of widespread abuse in American banking. Banks with powerful clients had access to extraordinary troves of confidential information, which could come in handy if those banks were to place bets of their own in securities markets. Such activity, Volcker wrote in his 2018 memoir, practically invites malpractice. Banks could wager billions of dollars at a time, bets that that would ultimately be dumped on the public if they backfired.

And so under the Volcker Rule, as Obamas new plan became known, banks would be barred from trading securities for their own profit.

The Volcker Rule wasnt just a banking reform. It was the final public act in one of the most influential American lives of the past century, and a symbol of the dominance that Volcker had come to exercise over the political imagination of the American elite.

Volcker, who died Sunday at the age of 92 , served three presidents in the Treasury Department, enjoyed a prestigious tenure at Chase Manhattan Bank, taught at Princeton University, and oversaw an international commission to compensate Jewish families fleeced by Swiss banks during and after the Holocaust.

He is best-known for his work as Chairman of the Federal Reserve from 1979 to 1987, where he became a figure of reverence in both Wall Street and Washington for his crusade against inflation. But there is far more to Volckers legacy than the consumer price level. More than any other single individual, Volcker assembled the economic architecture that has guided the United States for the past four decades. He revolutionized the role of the Fed, and transformed the way economic power is wielded and distributed in American life.

Most important of all, he became a champion for a way of thinking about politics, democracy and power that came to dominate not only the social circles of business-class Republicans, but the leadership of the modern Democratic Party.