Jonathan Lethem’s fat, hip and garrulous new essay collection, “The Ecstasy of Influence,” is self-consciously in the tradition of books like Norman Mailer’s “Advertisements for Myself” and John Updike’s “Hugging the Shore,” brilliant grab-bag volumes that blended criticism, journalism and introspection. So it makes a kind of sense that Mr. Lethem debated, he tells us, calling this book either “Advertisements for Norman Mailer” or, even better, “Shugging the Whore.”In an impish way, “Shugging the Whore” would have been perfect. It gets across Mr. Lethem’s antiauthoritarian streak, his instinctive distrust of preapproved canonical worthies like Updike, Saul Bellow and Thomas Pynchon. He’s a novelist who has spent a lifetime creating his own subversive pantheon, a jumpy CBGB’s of the literary soul.Mr. Lethem’s crowded pantheon, “The Ecstasy of Influence” makes clear, includes Marvel comic books and misfit writers like Philip K. Dick, J. G. Ballard, Shirley Jackson and Charles Willeford. It includes improvisational filmmakers like John Cassavetes, little-known bands like the Go-Betweens and rumpled, bohemian critics like Manny Farber. Mr. Lethem is all about the underdogs, and he counts himself snug among their number.“Most of my heroes,” he declares, “are partly or entirely out of print.” Mailer gets a hall pass because he is, like Mr. Lethem, from Brooklyn, and because he took a grizzled interest in things like “graffiti, underground film, marijuana and space travel.”Like almost everything Mr. Lethem has written, “The Ecstasy of Influence” is a reflection of, and a pixelated homage to, those whose work he fetishizes. If this book has a thesis, it’s this: For an artist, influence is everything. “Wasn’t the whole 20th century,” he writes, “a victory lap of collage, quotation, appropriation, from Picasso to Dada to Pop?” My iTunes and bookshelf, c’est moi.Mr. Lethem’s fullest and wittiest explication of this idea arrives in this volume’s now famous title essay, which appeared in Harper’s Magazine in 2007. A cosmic response to Harold Bloom’s seminal book “The Anxiety of Influence” (1973), Mr. Lethem’s essay argues for the eager plundering of earlier art to make new art. Even better, he makes this argument in a seamless piece of prose that, you discover at the end, is almost entirely plagiarized from other sources. This is a lovely trick shot, a think piece with its head happily up its own kazoo.The bummer — for me, though perhaps not for you — about most of Mr. Lethem’s riffs on his idols is that his tastes and mine, plotted on a Venn diagram, would hardly overlap at all. A little Philip K. Dick, J. G. Ballard and John Cassavetes, for me, go a long way. And about the whole Marvel comics thing, I’m with John Leonard, who observed about Mr. Lethem in The New York Review of Books in 2003: “It is time this gifted writer closed his comic books for good.”His tastes aren’t mine. Who cares? Not me, not usually. I like reading Mr. Lethem’s sentences, and I concur with H. L. Mencken, who wrote that the best critics “make the thing charming, and that is always a million times more important than making it true.” Yet lionizing underdog after underdog often leads Mr. Lethem to oversell their stuff, doing no favors to them or to him.In an essay reprinted here about the novelist Thomas Berger, for example, he seizes the opportunity “to shout that Thomas Berger is one of America’s three or four greatest living novelists.” To which anyone who has been paying attention — no disrespect at all to the gifted Mr. Berger — can only reply: Dude, please.Several of the essays here marinate in the fish sauce that is literary gossip. One is a short account of Mr. Lethem’s time at Bennington College in the 1980s (he dropped out during his sophomore year), where he knew Donna Tartt and Bret Easton Ellis. He had a falling-out with Ms. Tartt and, tongue slightly in cheek, wonders if she based the murdered Vermont farmer in her novel “The Secret History” on him.About Mr. Ellis, he writes: “Bret stood perfectly for what outraged me at that school, and terrified me, too, the blithe conversion of privilege into artistic fame. It was inconvenient that I liked him.” On the morning of 9/11, Mr. Lethem confesses, he was sleeping off a hangover after a decadent night in Manhattan with Mr. Ellis. He compares Mr. Ellis to a child star, unable to grow up. “I still found him a figure of sympathy, like rooting for Jose Canseco or Barry Bonds.”This same essay includes a drive-by tasering of Jonathan Franzen, about whom he declares, “His fame, then and now, had a Chauncey Gardiner quality, seeming called into being by a novelist-shaped vacancy on the cover of Time.”In an essay called “My Disappointment Critic,” Mr. Lethem zeroes in on The New Yorker’s book critic, James Wood, who reviewed his novel “The Fortress of Solitude” less than positively in 2003. Mr. Lethem used to feel that Mr. Wood was “the most apparently gifted close reader of our time.” Not so much anymore.For a sneaker-wearing boy from Brooklyn like Mr. Lethem, suddenly Mr. Wood’s “air of erudite amplitude veiled — barely — a punitive parochialism.” Mr. Wood, he says, writes like “an aristocrat who never really expected those below him to understand the function of the social order.” Another snooty writer, fired from Mr. Lethem’s canon.This feisty, freewheeling book also includes a very funny essay about being on a high-level book tour in America, about being whisked from radio and TV stations to lavish nightly meals. One problem, Mr. Lethem says, is that there’s rarely time to perform certain ablutions.Thus when you listen to writers being interviewed on some radio shows, he says, “you must know this: They are holding in a bowel movement.” Can our eyes unread that sentence? Can we ever listen to Terry Gross the same way again?