And Wall Street, Washington, the press corps, everyone sits and stares like so many dumb cows.

“The complicity on Wall Street is sickness!” Mr. Lewis says. He fixes you with his laser stare. “If you think the big firms are being honest” — his tone slides streetwise — “well, sweetheart, go think something else!”

The temptation is to dismiss Mr. Lewis, 73, as a crank, except he once ruled as an eccentric genius of arbitrage, with a preternatural feel for the tectonic movements of the markets. He has railed for decades about venalities now on daily display. Rude truth is his currency.

He knows Wall Street’s heights. He helped hire Michael R. Bloomberg, and he invested the money of two former Securities and Exchange Commission chairmen, making a fortune in the 1980s. And he knows its depths, since he pleaded guilty to stock manipulation in 1989, and was barred from the Street.

President Bill Clinton pardoned him, and a federal court judge later said Mr. Lewis acted out of pure reforming impulse.

But he remains in self-imposed exile.

Mr. Lewis wants to flip over Wall Street’s paving stones and search for worms. He relies on his singular strength: he discerns patterns where most see random data. He forecast the financial meltdown of 2008 that vaporized Bear Stearns, Merrill Lynch and Lehman Brothers. In 2006, he warned a Bear Stearns executive: “Bear is toast. Get out now!”