Years before David Foster Wallace popularized the extended digressive footnote, Baker stuffed “Mezzanine” with dozens of small-type, bottom-of-the-page mini-essays about doorknobs, staplers, plastic drinking straws and this one, about Jiffy Pop: “Jiffy Pop was the finest example of the whole aluminous genre: a package inspired by the fry pan whose handle is also the hook it hangs from in the store, with a maelstrom of swirled foil on the top that, subjected to the subversion of the exploding kernels, first by the direct collisions of discrete corns and then in a general indirect uplift of the total volume of potentiated cellulose, gradually unfurls its dome, turning slowly as it despirals itself, providing in its gradual expansion a graspable, slow-motion version of what each erumpant particle of corn is undergoing invisibly and instantaneously beneath it.”

Some critics have called this style miniaturist, which is true up to a point, and even minimalist, which seems all wrong. Baker prefers to think of himself as a maximalist: a writer who, in books where very little seems to happen, packs in “the most thought per elapsed unit of time.” Another way to think of his writing is that the kind of precision that Updike uses to render the background of his books becomes in Baker almost the whole point. In one of the very few passages in “U and I” that take issue with the master, Baker chides Updike for complaining about descriptive passages that “clog” a narrative and says: “The only thing I like are the clogs — and when, late in most novels, there are no more in the pipeline to slow things down, I get that fidgety feeling and I start bending the pliable remainder of the book so that it makes a popping sound, and I pick off the price sticker on the back and then regret doing so and stick it back on.”

Not surprisingly, Baker’s evolution as a writer has taken a roundabout route. He was born in New York City in 1957 but grew up in Rochester, where his father ran a small ad agency and his mother taught art. He went to a public experimental school, a place so free-form that there were no grades and his only transcripts were ones Baker typed himself. “At the time I thought: Give me structure!” he told me. “I yearned for a more traditional school. But now I think it was the best thing. I learned what it was like to be incredibly bored.” Baker’s main interest then was playing the bassoon, an instrument that originally appealed to him because he thought it looked like a steam engine and that he grew to love because of the beautiful middle-range melodies it could produce. At 13 he began taking lessons with Abraham Weiss, the principal bassoonist of the Rochester Philharmonic. Weiss was then only 21, and the two became unusually close. “I had a one-track mind when it came to music,” Weiss said recently, “and Nick had this incredible range of interests. It amazed me that he could be so good at the bassoon and also know all this other stuff. He was always using new words. I remember he came to a lesson once and he had the word ‘phlegm’ Scotch-taped to his bassoon.”

Baker eventually became good enough that when the Rochester Philharmonic needed an extra bassoonist for a Mahler symphony, say, he was enlisted. He had his own tux and union card. Weiss thinks that he was talented enough to make a life in music, but Baker disagrees. “I really practiced hard and got to a certain level of technical proficiency,” he said. “I overcame some of my limitations. I was a hard-working, dedicated bassoonist, but I have to say I’m not a natural musician.” He went for a year to the Eastman School of Music, in Rochester, and then transferred to Haverford College, where he majored in English. “The music wasn’t going to happen,” he said, “and I realized I had read so little. I didn’t know my way around any century. I was very underread.”

In his junior year at Haverford, Baker roomed in a co-ed dorm at neighboring Bryn Mawr, where he met and fell in love with Margaret Brentano, the daughter of a Berkeley history professor. She is now his wife. “It was incredible,” Baker said of that chapter in his life, which sounds like a more innocent, pre-lapsarian episode from “House of Holes.” “I’m very happy around women, and I had this tremendous experience there in the third floor of Rhodes Hall. Even the bathrooms were co-ed. It was very heady and exciting. I was very shy and somewhat awkward. I studied too hard. And to have this exciting dorm life was a whole new thing.” One way the students entertained themselves was by giving dramatic readings from the Penthouse letters department — the ones that begin, “I never thought I’d be writing this, but. . . .”

By then Baker already had notions of becoming a writer, even though one of his teachers put this comment on a story he turned in: “This, to be frank, is boring.” (Margaret remembers that he had a chart keeping track of all the rejection letters he received.) Before he became a full-time writer, though, Baker had a misguided interval of trying to be a businessman, and briefly even became a neoconservative. “I liked the idea of picking good companies and helping the American industrial miracle,” he recalled. “Now I have my reservations. I know I was a very confused young man.”