Even if you factored in the contingent leisure force, the hippie counterculture was small. The sensationalized press coverage of the period has left a permanent image of the late nineteen-sixties as a time when everyone was tripping or stoned. In 1967, when Didion’s article came out, only one per cent of college students reported having tried LSD. In 1969, only four per cent of adults said they had smoked marijuana. Recreational drug use soared in the nineteen-seventies, but the press was no longer interested. The whole thing had stopped being sexy.

Didion presented her article as an investigation into what she called “social hemorrhaging.” She suggested that what was going on in Haight-Ashbury was the symptom of some sort of national unravelling. But she knew that, at the level of “getting the story,” her piece was a failure. She could see, with the X-ray clarity she appears to have been born with, what was happening on the street; she could make her readers see it; but she couldn’t explain it.

In the preface to the book, she noted that no one had understood the article. “I had never gotten a feedback so universally beside the point,” she wrote. A few years later, in a radio interview on KPFR, she blamed herself. “Usually on a piece there comes a day when you know you never have to do another interview,” she said. “You can go home, you’ve gotten it. Well, that day never came on that piece. . . . That piece is a blank for me still.”

People liked the collection “Slouching Towards Bethlehem” (though it was not, at first, a big seller). People were intrigued by “Play It as It Lays,” Didion’s second novel, which came out two years later (though it got some hostile reviews). Mainly, though, everyone was fascinated by the authorial persona, the hypersensitive neurasthenic who drove a Corvette Sting Ray, the frail gamine with the migraine headaches and the dark glasses and the searchlight mind, the writer who seemed to know in her bones what readers were afraid to face, which is that the center no longer holds, the falcon cannot hear the falconer, the story line is broken.

Didion created the part—she was a master of the author photo—and she could have played it right up to the final curtain. But, after “Slouching Towards Bethlehem” and “Play It as It Lays,” she completely reassessed not only her practice as a journalist but her understanding of American life, her politics, and even the basis of her moral judgments. She decided she wanted to get what she had failed to get with the hippies. She wanted to get the story.

Tracy Daugherty’s “The Last Love Song” (St. Martin’s) is a biography of Joan Didion written partly in the style of Joan Didion, a style of ellipses, fragments, and refrains. This is not what you ideally want in a biography. The point of a biography is to reveal what’s behind the ellipses. Daugherty operated under difficulties, though. He was unable to persuade Didion to coöperate, and it’s obvious that many people close to Didion refused to talk to him as well.

That doesn’t mean that he wasn’t thorough. He had access to Didion’s papers, housed at Berkeley, and a large amount of information was already out there. For someone with a reputation for being guarded and tongue-tied, Didion did a lot of promotion. She went on book tours and submitted to profiles. She did radio; she did television; she talked to Publishers Weekly. It added up.

She also wrote obsessively about herself—not only in her memoirs, “The Year of Magical Thinking,” about the death of her husband, and “Blue Nights,” about the death of her daughter, but in reported pieces and in personal essays, which she started producing almost as soon as she started publishing. (She eventually got bored with the genre and gave it up. “I didn’t want to become Miss Lonelyhearts,” she said.) She once delivered a lecture called “Why I Write.” She began by pointing out that the sound you hear in those three words is “I, I, I.”

Much of “The Last Love Song” is therefore an intelligent and elegant paraphrase of things Didion has already said or written. There is some sniping from the odd acquaintance or estranged friend, but revelations weren’t in the cards. The “real” Didion Daugherty shows us is just the obverse of the image: ambitious (hence the anxiety), controlling (hence the brittleness), and chic (hence the Corvette).

You could work up a dichotomy here, but it doesn’t get you very far. Didion and Dunne made an excellent living as Hollywood screenwriters and script doctors. They lived in Malibu and then in Brentwood Park, O.J.’s old nabe, and were part of the Hollywood talent élite. Dunne’s brother Dominick was a producer for movies and television; their nephew was Griffin Dunne, the actor. And Didion knows something about fashion and style—she began her career at Mademoiselle and Vogue. But there’s no reason that any of this should be incompatible with one day writing about death squads in El Salvador.

John Dunne was a gregarious man, a social drinker and a raconteur, and he and Didion worked up a sort of Penn and Teller routine. One sang, the other mostly didn’t. They rarely gave separate audiences. If you asked to speak to one, you almost invariably spoke to both, even on the telephone. “I was at first surprised that John Dunne sat through most of the interview and did nearly all the talking,” Susan Braudy wrote after interviewing Didion for Ms., in 1977. Didion’s explanation is that she isn’t a talker; she’s a writer. “I’m only myself in front of my typewriter,” she finally told Braudy. There is no reason to doubt this. The person we’re interested in is the person on the page.

It’s a common mistake, in assessing Didion’s work, to interpret her sensibility as a reflection of the times—to imagine, as Daugherty puts it, that she has “always spoken for us.” That’s certainly not the way she has presented herself. In a column she started writing for Life in 1969, she introduced herself as “a woman who for some time now has felt radically separated from most of the ideas that seem to interest other people.” She’s not like us. She’s weird. That’s why we want to read her.

Didion came from a family of Republicans. She was born in Sacramento in 1934, a fifth-generation Californian. Her father started out in insurance, speculated in real estate, and ended up spending most of his career in the military, a very California trifecta. Turned down by Stanford, Didion attended Berkeley, in an era when campus life was socially conventional and politically dormant. In 1955, she won a guest editorship at Mademoiselle and spent a few months in New York City. A year later, she won a similar contest at Vogue, and she moved to New York in the fall of 1956 and began her magazine career there. Leaving home, she later said, “just seems part of your duty in life.”

Didion worked at Vogue for ten years. She continued to write for Mademoiselle, and, in 1960, she began contributing to National Review, William F. Buckley’s conservative magazine. She wrote pieces about John Wayne, her favorite movie star, and, in the 1964 Presidential election, she voted for Barry Goldwater. She adored Goldwater. It was hardly a surprise that she found Haight-Ashbury repugnant. Her editors at the Post understood perfectly how she would react. They designed the cover before she handed in the piece.