Twenty five years ago I quit a job on Wall Street to write a book about Wall Street. Since then, every year or so, UPS has delivered to me a book more or less like my own, written by some Wall Street insider and promising to blow the lid off the place, and reveal its inner workings, and so on. By now, you might think, this game should be over. The reading public would know all it needed to know about Wall Street, and the publishing industry would be forced to look to some other industry for shocking confessions from insiders. Somehow this isn't the case. The inner workings of our biggest financial firms remain obscure to the general public, and their outer workings still promise to shock. To writers and publishers at least, our financial system has become the gift that keeps on giving, like one of those trick birthday candles that, no matter how hard you blow on it, flickers back to life.

Enter Greg Smith, in the latest attempt to extinguish the eternal flame. Why I Left Goldman Sachs began last year as the most e-mailed and talked-about opinion piece that The New York Times had published in a long time. Here the author recounts how he spent most of the six months leading up to last March working at Goldman by day while writing up his deeply felt grievances against Goldman by night. When he finished he had a 1,500-word counterblast but no place to put it: he e-mailed it to the general address for blind submissions to the Times op-ed page. He heard nothing for a month, and so finally dug out the e-mail addresses of four Times editors, and sent his piece to all of them. The next morning the Times got in touch with him. (There's a lesson here for aspiring Times op-ed writers.) Skeptical that a Goldman Sachs employee was prepared to break ranks, the Times sent a reporter over to Goldman's London office—where Smith worked—to confirm his existence. The day before the paper finally published his piece Smith went into Goldman, cleared out his stuff, and caught a flight back to New York. When the piece hit the Web, he appears to have been somewhere over the Atlantic. It and he were instant sensations.

In his piece Smith argued that, in the decade since he joined Goldman Sachs out of Stanford University, the firm had become corrupt. He hadn't seen anyone at Goldman do anything illegal, but he had seen them do a lot of things that he considered shameful. Goldman now rewarded its people for advancing their narrow interests at the expense of their customers, the wider society, and even the firm's own long-term interests. Since the route to the top of Goldman had changed, the sort of people who ran Goldman had changed, too:

Leadership used to be about ideas, setting an example and doing the right thing. Today, if you make enough money for the ﬁrm (and are not currently an ax murderer) you will be promoted into a position of inﬂuence. What are three quick ways to become a leader? a) Execute on the ﬁrm’s “axes,” which is Goldman-speak for persuading your clients to invest in the stocks or other products that we are trying to get rid of because they are not seen as having a lot of potential proﬁt. b) “Hunt Elephants.” In English: get your clients—some of whom are sophisticated, and some of whom aren’t—to trade whatever will bring the biggest proﬁt to Goldman. Call me old-fashioned, but I don’t like selling my clients a product that is wrong for them. c) Find yourself sitting in a seat where your job is to trade any illiquid, opaque product with a three-letter acronym.

None of this exactly came as news. The news was that a living, breathing Goldman employee had said it. There was also, between the lines, a fresh hope: Goldman had employed an idealist! For a decade! Either that, or this not-so-young investment banker was saying what he was saying because he had figured out that it paid him to say it. In a way that was the more hopeful thought: that the calculations propelling legions of self-serious Stanford graduates to Goldman Sachs since the early 1980s were now, perhaps, about to propel them in a different direction.

Either way, you had to admire Greg Smith's nerve. Still, his piece raised a couple of questions that I hoped his book might answer. The first is, why now? Goldman was helping the Greek government deceive the European Union about its indebtedness back in 2001; by 2004 the firm was busy manipulating the ratings agencies and the investing public to help expand the market for subprime mortgage bonds; by 2006 it was designing securities to fail (the infamous Abacus program) so that its own traders could bet against them, and make profits at the expense of their own customers by, in effect, pumping vast amounts of trust-reducing pollution into the financial system. For a very long time now the firm has been famous for being more frightening than helpful to its customers. Smith first worked for Goldman as an intern in the summer of 2000, near the peak of an Internet bubble that was inflated with the help of Goldman's analysts. If some Goldman employee was going to go and get himself worked up over his firm's destructive financial behavior, why did it take him until last spring to do it?