If you think that people in the upper echelons of finance and government are all-knowing and all-powerful, you ought to read Timothy Geithner’s new book, “Stress Test.” You’ll see that he and the other high-level types he dealt with are smart and hardworking, but screw up plenty of times.

The book, like Geithner himself (at least in his dealings with me), is disarming, down-to-earth, witty and self-effacing. In fact, “Stress Test” might more accurately be called “Feet of Clay.” As in, “Even the gods have feet of clay.” You know, they aren’t remotely perfect.

Geithner was head of the New York Fed for five years before spending four years as treasury secretary. A lot of power, right? But he remembers some less-than-godlike moments as he tried to avert financial calamity in 2008: “I got a nasty case of poison ivy, so I worked for weeks with my legs slathered in Calamine lotion and wrapped in gauze. I once walked from my office to a conference room with a long train of Calamine-covered gauze trailing from my pant leg.” Trailing gauze rather than glory, a hilarious image.

There are repeated descriptions of how Geithner angered and disappointed his wife, Carole, when he would come home late, be preoccupied with work, miss important family events and repeatedly uproot the family to follow his ambitions. That’s real-world stuff, not the fantasy world in which people like Geithner are generally portrayed as either gods (if we approve of what they’re doing) or devils (if we don’t).

I love the fact that the book’s index has more entries for Carole Geithner (31) than for Ben Bernanke (29). To me, that’s a sign that Geithner worries an awful lot about the right things: his wife and kids. (Okay, there are 37 entries for Larry Summers, formerly Geithner’s boss and mentor, later his rival and competitor. But hey, I said he wasn’t perfect).

The most entries of all — 42 — are for “Lehman Brothers, collapse of.” And rightly so. Because Lehman’s bankruptcy, in September of 2008, set off a series of events that almost capsized the world financial system and required massive intervention by the world’s governments and central banks.

Why was Lehman allowed to fail?

Here’s Geithner’s version: “We had been powerless, not fearless. We had tried but failed to prevent a catastrophic default. That’s still poorly understood, in part because Hank [Paulson, then secretary of the treasury] and Ben [Bernanke], who had the thankless job of explaining our actions, decided not to admit defeat in public. They thought at the time that confessing we didn’t have the firepower to save Lehman would intensify the panic, which may have been right.”

Compare that with the account by Neil Irwin in his 2013 book, “The Alchemists.” Irwin, then at The Washington Post, currently at the New York Times, wrote that the Fed misled people intentionally:

“By the time Lehman was on the brink, the crisis fighters were running up against the legal and political limits of their ability to stop it from going under. That, however, wasn’t what they told the outside world at the time. They wanted to project confidence and calm, to give the impression that the Lehman bankruptcy was a deliberate decision they’d made out of their convictions that the financial markets were sufficiently prepared for the possibility of such a failure — which had seemed imminent ever since the near collapse of Bear Stearns six months earlier. That was the message Fed officials voiced to reporters, their contacts in the markets, and even other central bankers.”

I’m one of the reporters who got that message from the Fed — off the record, of course. So although I like and respect Geithner, I’m less than sympathetic to his “it’s poorly understood” lament. Besides, it’s tacky for him to put all the blame on Bernanke and Paulson.

Now, though, I’ll come to Geithner’s defense. He’s gotten grief for writing that U.S. taxpayers have made money on the bailout of the financial system, rather than losing hundreds of billions of dollars as most people believe. Geithner puts the profit at $166 billion as of year-end 2013.

I can relate. In 2011, my then-colleague Doris Burke and I wrote that taxpayers would come out ahead on the bailout. We got a lot of grief for saying that — but it turned out to be true. I’m glad that Geithner pointed it out. By my math, the profit is probably about $300 billion.

Yes, Geithner has feet of clay. But he has plenty of good moments in “Stress Test”—and his bailout math is one of them.

Sloan is Fortune magazine’s senior editor at large.