People who filed for bankruptcy were genuinely in over their heads, the researchers found. They had accumulated debt they couldn’t repay because they had lost their jobs or had some other life event that robbed them of their ability to earn a decent paycheck. They were often middle class, homeowners even. They filed for bankruptcy because they were desperate. Looking through thousands of bankruptcy filings, Mr. Westbrook said a few days ago, “you got a sense of human beings in real trouble.” He added, “All of us were very much affected by what we found in those files.”

By the summer of 2007, when Ms. Warren proposed the consumer agency, she was a well-known advocate for financial consumers  and the scourge of the credit card industry. She coined the term “tricks and traps” to describe how the banks lulled people into agreeing to credit card terms they weren’t even aware of when they signed up for the card. She had testified before Congress many times.

In the article where she proposed the new agency  she called it the financial product safety commission  she began with an analogy to toasters. (Ms. Warren has a thing for toaster analogies.) “It is impossible to buy a toaster that has a one-in-five chance of bursting into flames and burning down your house,” she wrote. “But it is possible to refinance an existing home with a mortgage that has the same one-in-five chance of putting the family out on the street.” Her timing could not have been better, she wrote the article at the exact moment the subprime bubble was reaching its peak.

What struck me, when I reread that article recently, was the bluntness of her language. She used words like “tricks,” “fleece,” and “bribe” to describe the actions of mortgage and credit card lenders. And I think a lot of her appeal stems from that simple fact: she describes abuses  predatory lending, hidden fees, bewildering “disclosures” that hide more than they disclose  in precisely the way most Americans have experienced them. She conveys a powerful sense that she understands what we’ve been through this last decade.

Her critics have complained that in her quest to avenge the downtrodden consumer, she could endanger the safety and soundness of banks, by writing rules that would strip them of billions in profits. Her essential position is that if taking advantage of borrowers is necessary to save the banks, then there is something deeply wrong with the banking system in America. The American Bankers Association may not agree with that, but that is unquestionably what most Americans believe. And they are right.

Ms. Warren also conveys a powerful sense of optimism about the good the new agency can do. I saw this for myself just a few days after President Obama signed the new law, when she was part of a panel discussion by the Roosevelt Institute, a liberal policy research organization that focuses on financial issues. I was also part of that panel, but after listening to Ms. Warren speak, I felt a little like Ms. Abaunza. I was bowled over.

That afternoon, Ms. Warren conveyed a great deal of passion, energy and historical knowledge about consumer lending practices. She gave a minitutorial about the history of usury laws, and about how credit card disclosures had become a tool for gouging customers.