Former U.S. Treasury Secretary Timothy Geithner defended his role in the tax-payer bailout of banks and applauded President Barack Obama for rescuing the American economy last night in Cambridge before an audience of nearly 300. Many of his critics believe that Geithner, promoting his new book, “Stress Test,” did more to help the financial sectors than the middle class.

Geithner’s stress test was an economic measure to determine the viability of banks and other financial institutions in 2008. But the phrase could very well apply to the Treasury Secretary's national book tour where he has encountered both friendly and adversarial audiences. The people that turned out for the Harvard Book Store-sponsored event at the First Parish Church were somewhere in between.

Questioned on stage by Harvard University’s David Gergen, Geithner said in his first few days on the job in the Obama Administration he drew upon lessons from the Great Depression and his experience at the side of Clinton treasurer, Robert Rubin, in learning how to navigate the Recession of 2008.

"Basically all of the investment banks were at the edge of collapse, and so was AIG, so what we did was a very novel thing, which is the title of my book, which is to design the strategy to get the system working again," he said. "And again, we used a pretty counterintuitive, scary thing for people at the beginning. We said we're going to force a level of transparency on banks, that they'd never been subjected to, so people could see what losses they might face in a great depression."

There was also also worry about digging Banks out of the deep financial holes that a majority of Americans believed the so-called too-big-to-fail institutions had burrowed.

"We laid out this thing they'd never heard of, called a stress test," Geithner said. "Completely untested, deep skepticism around it. It took a sustained effort of gradually revealing the details around it to reassure people, and it was very effective."

Effective, that is, compared to other possible outcomes like the decade-long trauma of the Great Depression.

And then came the hard questions: Writing on a card, someone in the audience wanted to know why none of the bankers believed to be responsible for the financial crisis went to jail.

"I think it is demoralizing," he said. "I think Americans deserve a tougher enforcement response."

Geithner says he too is frustrated.

"We ran a financial system for decades where we didn't put a set of clear rules, constraints on a bunch of behavior that was terrible — you know, a lot of predatory abuse, and things that were damaging took place in what is the modern equivalent of the Wild West of our financial system," he said.

But Geithner’s longtime nemesis in Washington on all things financial—Sen. Elizabeth Warren—speaking in this same space weeks ago, said:

"The big banks—they cheated American families, they crashed the economy, they got bailed out, and now the big five financial institutions are 38 percent bigger than they were back in 2008," Warren said. "The game is rigged. The game is rigged."

Gergen asked Geithner if that was true.

"There's still tremendous inequality in the opportunity people have in this country today," Geithner said. "And our political system is frozen—I think mostly by politics and ideology—but it's frozen in part by money."

Six years since the financial crisis that stripped Americans of jobs, homes and pensions, Geithner says he is still concerned about the county’s fiscal health and the prospects for weakening the pillars of inequality. He has moved on to the private financial sector but believes the government to be the only viable institutional option for making long term change:

"These aren't things, challenges that are beyond our power to fix as a country," Geithner said. "They just require, again, rediscovering this basic, pragmatic capacity to govern that has been a source of so many of our advantages as a country, but we seem to have lost."