As tragedies go, not getting what you want is the straightforward kind, and getting it can be the ironic variety. But there is also the existential tragedy of not knowing what you want to begin with. That’s the species of catastrophe recounted in Walter Kirn’s memoir, “Lost in the Meritocracy: The Undereducation of an Overachiever,” the witty, self-­castigating story of the author’s single-minded quest to succeed at a series of tests and competitions that took him from one of the lowest-ranked high schools in Minnesota to Princeton. As Kirn, a noted critic and novelist, tells it, in childhood he leapt onto a hamster wheel baited with “prizes, plaques, citations, stars,” and kept rattling away at it until his junior year in the Ivy League, when he suffered a breakdown that left him nearly speechless.

Kirn cracked up as he began to suspect that he was approaching the end of the line. He didn’t especially desire money or power, and even his appetite for renown was quixotic. (He spent one summer bar-backing for a legendary mixologist in Munich, thinking: “This was true fame I was witnessing, true mastery. I should stay and learn from it.”) Up to that point, he’d devoted his whole life to “the great generational tournament of aptitude” in which “the ranking itself was the essential prize.” Somehow he’d made it through three years of college without seriously considering what he intended to do once he got out.

Like many memoirs, “Lost in the Meritocracy” combines penetrating shrewdness with remarkable blind spots. Take the book’s central question: How did anyone as smart as Kirn get into such a fix? The implication of the title is that “meritocracy” itself was to blame. Kirn grew up in the 1960s and ’70s, when technocrats were thoroughly systematizing American public education. In his suburban grammar school, subjects like art and music were formed into “units” and “modules,” implying that “learning could be engineered, and that it had been, perhaps by government scientists — the same ones behind the Apollo program, maybe.” At the same time, the teachers were squishy, easily flattered and willing to coo over any creative daub that seemed to express “feelings.” “Art” could be whatever he said it was, Kirn realized, and producing it was the equivalent of such apple-polishing activities as emptying the classroom pencil sharpener. When he concocted bogus stories about the emotions that supposedly inspired his projects, he won “praise, and sometimes hugs, eventually convincing me that art was about one feeling above all others: being loved.”

So there you have it: the young Walter Kirn quickly learned that achievement could be precisely quantified, but also that the system for arriving at that quantification could be gamed. “I was the system’s pure product,” he writes, “sly and flexible, not so much educated as wised up.” He figured out how to turn a teacher’s question inside out and parrot it back in a simulation of thoughtfulness. If asked, “How does racial prejudice contribute to inner-city hopelessness?” he’d reply, “Is our conception of ‘inner-city hopelessness’ perhaps in itself a form of prejudice?” A maestro of multiple choice, he managed to ace his SATs despite having cracked only three “serious novels” by the age of 16: “Frankenstein,” “Moby-Dick” and “The Great Gatsby.”

At Princeton, however, he discovered the limits of his facility. He could beguile a professor into thinking he understood such concepts as “liminal” and “valuational,” but his peers unerringly recognized his scholarship-boy status. The heiress girlfriend of one of his freshman roommates offered him some Champagne her father had sent her, then tried to charge him for his portion of the bottle. His roommates replaced their suite’s shabby furniture, then banned Kirn from the common room when he refused to pony up $600 as his share. In no time, the suite became “a concentrated version of what the whole campus would come to represent for me: a private association of the powerful which I’d been invited to visit on a day pass that, I sensed, might be revoked at any time as arbitrarily as it had been issued.”

In one respect, Kirn lucked out: his college years coincided with the ascendancy of “theory” in American academia. Since hardly anybody understood the deconstructionists to begin with, it was that much easier for Kirn to bluff his way through, powered by bravado alone. Better yet, theory was intent on proving the illegitimacy of all those great books he’d never read. “We skipped straight from ignorance to revisionism,” he writes of his cohort, “deconstructing a body of literary knowledge that we’d never constructed in the first place.”

On campus, Kirn cultivated an identity as an avant-gardist. He wrote pretentious plays and poems about “the creeping loss of ‘personhood’ in an era of technological change.” He called his social crowd “the Joy Division” after the postpunk band he pretended to like while secretly thinking that their music sounded “like noise in a coma victim’s brain.” On a trip to Manhattan (to buy drugs with a self-styled Marxist who regarded flushing the toilet as “unpaid labor”), he hung out with a rich girl in an apartment downstairs from Truman Capote’s and overlooking the U.N. Her skin, he marveled, looked like it might have been “harvested, through some blasphemous new process, from the wrists of infants.” His life was a Jay ­McInerneyish scenario, which is to say a Gatsbyish scenario, but Kirn was incapable of grasping this because he’d ludicrously misconstrued Fitzgerald’s novel as an “invigorating chronicle of several high-spirited Midwesterners storming through the mansions of the East.”

No one could be harder on the youthful Kirn than he is on himself; he has to be. He has the satirist’s cruel knack for conjuring and dispatching an individual in a single line, like the “computer whiz” described as having “all the characteristics of a bad stutterer without the stutter itself.” You can’t dish that stuff out unless you’re willing to take most of it, at least not without making yourself hateful to your readers. “Lost in the Meritocracy” betrays the roots of this skill in a wobbly notion of the self as a void encased in a posture. But did “the meritocracy” cause Kirn’s chronic hollowness, or was it simply the vehicle at hand, ideally suited to a boy starved for approval? His parents — a restless, titanically self-involved father and a mother who cultivated her inner life in strict solitude — seem a much likelier source for his condition. It was only after Princeton, while holed up with his mother’s little stash of “classics for the masses,” that Kirn finally summoned enough faith to risk losing that fragile self in other people’s books. You lose it, but it always comes back. That’s one of the ways of learning it was there to begin with.

‘We’ve got to get home and start reading,” said one of the teenage girls tearing out the door of the small-town Borders where I bought my copy of Breaking Dawn a few minutes after midnight on Aug. 2. Ardent fans of Stephenie Meyer’s blockbuster series about perpetually swooning Bella Swan, her vampire sweetheart, and the various werewolves and bloodsucking freaks who populate her world aren’t waiting for a cool critical appraisal of this final installment to decide whether it’s worth their time. You succumb to Meyer’s novels as you do to a powerful, slightly ridiculous dream. Or you don’t.

Here’s a third possibility: You whip through Twilight, New Moon, and Eclipse, then abruptly lose all patience with the franchise midway through Breaking Dawn, when Meyer takes her supernatural love story several bizarre steps too far.

Dawn begins days before 18-year-old Bella’s wedding to Edward Cullen, whom she has worshipped since she first arrived in the drizzly town of Forks, Wash., three volumes and 1,700 pages ago. Back then she was the new kid in town, insecure and crushing madly on the cutest boy in school, who just happened to be a vampire. (He’s part of a polite coven who drink animal blood.) Now, after countless misunderstandings and estrangements, after outsmarting evil fiends and consorting with cuddly werewolves, Bella finally has what she has always wanted: Edward. ”He had the most beautiful soul, more beautiful than his brilliant mind or his incomparable face or his glorious body,” Bella coos. Yes, you need to plow through acres of this kind of goo in all Meyer’s novels, but they move so quickly you hardly notice.

The couple has made a pact. Edward will transform Bella into a vampire — a fate she has pleaded for — but only after they enjoy a ”real” honeymoon, complete with vampire-on-human sex. So, off to a tropical island the newlyweds jet to at last consummate their long-simmering love. Like many of his kind, Edward gets a little wild in the sack; he shreds pillows and destroys the headboard of a bed during their coupling, and bruises Bella all over her body. Happily for her, though somewhat upsettingly for the reader, she is so transported by erotic rapture that she fails to notice: ”I only remembered wanting him to hold me tighter, and being pleased when he did….” If this sounds steamy, rest assured (or don’t get your hopes up): Meyer writes about even furniture-wrecking sex with the decorum of a Victorian schoolmistress.

She is less restrained, alas, in her macabre descriptions of the pregnancy that immediately follows. Any reasonably astute reader will guess that Edward has knocked Bella up — inexplicable nausea, gnawing hunger — long before she figures it out herself. And it’s when Bella, suffering from morning sickness and gestating a vampire, starts vomiting ”a fountain” of blood, that Meyer jumps the shark.

The series has always been grounded in Bella’s human voice, which is imbued with adolescent fragility and unwavering passion for Edward, which, however goopily described, has a kind of winsome purity rare in young-adult fiction. You may wish she had loftier goals and a mind of her own, but these are fairy tales, and as a steadfast lover in the Disney princess mold, Bella has a certain saccharine appeal. As the masochistic teenage mother-to-be of a monster — a fetus that breaks her ribs when it kicks — she is not only hard to identify with but positively horrifying, especially while guzzling human blood to nourish the infant. (She adamantly refuses an abortion, which even Edward begs her to consider.) By the time the feverish birth scene rolls around, you’ll think Rosemary’s Baby might make a suitable companion video to What to Expect When You’re Expecting.

And this is just the beginning.

During the loonier stretches of the novel, Meyer wisely turns the narration over to Bella’s old friend Jacob, a warmhearted werewolf who has always been sweet on her. He becomes our tenuous anchor to sanity, as outrageous new plot twists sprout like kudzu. ”I felt like — like I don’t know what. Like this wasn’t real. Like I was in some Goth version of a bad sitcom,” Jacob confides before he too is swept up in the narrative mayhem. So do we, Jacob. So do we.