For most writers, cool is a word that rarely tops the list of personality descriptors. Neurotic and introverted are generally in heavier rotation. For women writers, you can add solipsistic and confessional.

Maybe that’s part of the reason Joan Didion, who’s been called all those things but for whom cool is surely the most frequently applied adjective, has never been just an inspirational figure. She has been an object of aspirational longing. Revered (worshipped, in many cases) as much for her glamorously aloof public persona as for her infectious, revolutionary-in-its-time prose style, Didion was—and remains—famous in a way that writers seldom are anymore (and, though some of today’s embittered literary types like to believe otherwise, seldom were even back then).

It’s remarkable, then, that Tracy Daugherty’s The Last Love Song is the first full-length biography ever published of Didion. Given the number of writers who, especially early in their literary lives, go through a period of Didion-mania intense enough to put most of her vital statistics permanently at their fingertips (the rain-soaked silk curtains in the apartment on 75th Street! the house on Franklin Avenue! the Corvette!), you would think we’d have seen at least as many biographies of her in the past 40 years as have been written about Taylor Swift in the past two (nine, if you must know).

But with coolness comes caginess, not to mention friends and associates who know better than to talk to biographers about living subjects, particularly ones whose recent pasts have been marked by the kind of tragedy that effectively cordons them off from outside inquiry. That Didion, though now 80 years old and frailer than ever, is very much alive and apparently in full command of her intellectual capacities would, at least for many biographers, make her too terrifying to touch.

Fortunately, Daugherty, a fiction writer and an essayist, and the author of biographies of Donald Barthelme and Joseph Heller, knows exactly how much pressure to apply. His excellent and exhaustive book—he draws from a voluminous cache of material, including a conversation I had with Didion in 2003—manages to be provocative without being exactly juicy. Though he digs as deeply as he can, he never plays dirty. He writes:

In choosing Didion as a subject, I am abjuring abstractions (“the madness of the artist”), avoiding pat explanations of personal antics (booze, gender, trauma, even when they do inform the story), weighing conflicting testimonies, and scouring the public record for the underreported fact, the contradictory details.

Daugherty divides the book into nine sections, beginning, as Didion herself did in 1934, in California’s Central Valley. The daughter of Frank and Eduene Didion, who both came from what a local historian calls “Sacramento’s landed gentry,” Didion grew up in dusty privilege, though Frank was less than a model of stability. He dragged the family through an itinerant period while serving stateside in the military during World War II and, a decade or so later, spent time in the neuropsychiatric ward of a San Francisco hospital for depression.

St. Martin’s

That last detail may not surprise readers, given the chronic melancholia and hovering paranoia that became Didion’s default setting both on and off the page. But Daugherty portrays that emotional fragility as actually something of a matrilineal trait. “If Didion’s memory is correct,” he writes, “her mother seems to have planted the idea in her daughter’s mind that she was too delicate and sensitive for her own good, in the manner of all the family women.” Eduene, who “ ‘gave teas’ the way other mothers breathed,” according to Didion, handed her fretful child a notebook as a kind of pacifier. Instead, Daugherty writes, “the notebook tugged her toward an inner life, a private world brewing storms beyond her mother’s control.” Still, for all her investment in her daughter’s brittleness, it was Eduene who talked to Didion like a grown-up, indulging her fantasies of urban sophistication—“I kept playing around with writing and imagining being a writer, which usually involved having a quote-unquote Manhattan penthouse,” Didion has said. In 1955, while a 20-year-old student at Berkeley, Didion applied to Mademoiselle’s guest-editor program, a plum assignment that involved a month-long stay in New York, and was accepted.

Though Didion didn’t become a bona fide star until after she decamped to Los Angeles in the mid-1960s, her legend may as well have begun the moment she stepped off the plane at Idlewild in the spring of 1955 for the Mademoiselle post. The exhilarations and despondencies of that summer—and those of the years in New York that followed—are what she went on to capture with famously visceral precision in “Goodbye to All That.” The tone and spirit of that seminal 1967 essay have been internalized, and in many cases downright copied, by countless young writers who came along in her wake.

In charting this period, Daugherty relies heavily on interviews with Noel Parmentel, a journalist and filmmaker who was a gadflyish fixture on the 1950s New York literary scene. He functioned for Didion as a combination of mentor and suitor (though years later, their friendship ended when Parmentel recognized himself in the abusive, alcoholic character Warren Bogart in A Book of Common Prayer). The young Didion, new to the city and writing fashion copy by day while working on a novel at night—“I never saw ambition like that,” Parmentel once said—cut a pathologically shy profile. But Parmentel, who called her “that mouse,” considered her eminently worth knowing. He procured professional and personal introductions, including, one night in 1958, to John Gregory Dunne, about whom he told her, “This is the guy you ought to marry.”

If Didion and Dunne were in some ways opposites in temperament (he could be irascible and prone to grudges), they shared a class sensibility that Didion found comforting. She noted similarities between Dunne’s hometown of West Hartford, Connecticut, and her own. “The minute I got into this house of great calm and order and peace and well-being,” she has said of her first visit to his childhood home, “I thought, I want to marry him … There were meals. There was a closet full of organdy tablecloths on long rollers—the way they came back from the French laundry, under tissue.”

The sweeping scope of The Last Love Song offers room for two mini-biographies within the main biography, one of Dunne, whom Didion married in 1964, and the other of the couple’s adopted daughter, Quintana Roo. On Dunne, Daugherty is respectful but also forthright about the demons and deficits that at times posed threats to marriage and career alike. Though Didion’s line about traveling to Honolulu “in lieu of filing for divorce” (which shocked readers of Life magazine in 1969) became one of her best-remembered, Dunne was no less candid about the couple’s troubles.

“Dunne often told friends at parties during this period—sometimes joking, sometimes not—that his marriage was a week-to-week affair,” Daugherty writes. In his “fictionalized memoir,” Vegas, Dunne offers a scene in which his character calls his wife from his temporary apartment and tells her he has a date that night with a 19-year-old who’s “supposed to suck me and fuck me.” “It’s research,” the wife responds casually.

As Daugherty sees it, the marriage suffered not just from “the stresses of writing, money, lots of drinking,” but also from the disillusionment born of realizing that an egalitarian partnership is perhaps more oxymoron than attainable goal.

Though neither could imagine not being married to a writer, though they counted on each other for editorial and professional support, an edginess grew between them—not competition so much as sadness that things could not always be equal.

The marriage eventually found, if not true equality, at least its equilibrium, largely thanks, Daugherty suggests, to Dunne’s having greater standing in Hollywood when the couple’s screenwriting collaboration took off in the early 1970s.

Subsequent decades saw Didion’s fiction and nonfiction veer toward the political. She covered the American military presence in El Salvador, wrote about Cuban exiles in Miami, and published the Vietnam War–era novel Democracy. Her 17,000-word essay, published in The New York Review of Books in 1991, about the five teenagers falsely convicted in the Central Park–jogger trial represented one of the first divergences from the generally accepted theories about the case.

By then, the couple was back living in New York, where, in 2003, Dunne collapsed from a fatal heart attack in the couple’s Upper East Side apartment. Less than two years later, Quintana died of acute pancreatitis at age 39 after a series of hospitalizations and just before the publication of The Year of Magical Thinking, Didion’s chronicle of the aftermath of Dunne’s death and her best-selling book to date. In Blue Nights, published six years later, Didion sets out to write Quintana’s elegy, but understandably and perhaps inevitably, can scarcely bring herself to the task.

Fortunately, Daugherty picks up the slack, showing impressive restraint while also doing his due diligence and asking many questions that, in Blue Nights and elsewhere, Didion leaves largely untouched. Was Quintana’s prodigious drinking (a trait she shared with her parents but may have been physically less well constituted to handle) a cause of her illness? Who exactly was Gerry Michael, the widower in his 50s whom she married in 2003, five months before she fell ill? To what degree might Quintana’s psychiatric struggles—which in Blue Nights Didion confines to phrases like suicidal despair and a flummoxing array of diagnoses (manic depression, obsessive-compulsive disorder, borderline personality disorder)—have been connected to a childhood spent at Hollywood parties and in far-flung hotel rooms? To what degree might they have been inherited from the chaotic biological family with whom she reluctantly reconnected in 1998?

Daugherty gets only so far. “Acute pancreatitis,” he allows, is “an inflammation and infection of the pancreas usually caused in young people by prolonged drug or alcohol abuse.” Quintana met Michael, a former rock drummer, at the Mayfair, a Manhattan bar that she frequented and he tended. Daugherty cites a childhood friend of Quintana’s who “believed Quintana’s depressions and drinking were ‘probably intertwined’ with her final illnesses.” As for Quintana’s birth family, whom Didion excoriates in Blue Nights, Daugherty writes that he “felt obligated” to try to locate them “to see if their story illuminated anything about Didion.” That he could find “no legal path around” sealed adoption records in California Family Law was “bad news for my book,” he writes, “but soothing to me as a citizen.”

Daugherty means as an American citizen, but he may be talking as well about literary citizenship, given that remaining in good standing on that terrain seems to require the delicate treatment of certain legendary figures. In the case of Didion, there has always been something uncouth about asking too much, pressing too hard. You can imagine even the most intrepid and meticulous biographer—and Daugherty certainly qualifies—running into roadblocks on the Didion path and letting out a relieved “Oh, well!” That’s because Didion not only has been granted special status by virtue of her age and the tragedies she’s endured. She also occupies the rare cultural position of having been a sacred cow (or sacred mouse) from almost the beginning. The gushing love she gets from readers and fellow writers has often been characterized as obsessive, but it’s always been, at its root, protective. To be a Didion fan is to be a defender of the sharp and brutal edges, a champion of the dispassion, a forgiver—even an appreciator—of the simmering elitism.

In an era when discussions of privilege and gender have become preoccupations in certain corners of the media and, in some circles, feelings have been granted equal status with facts, it’s interesting to think about how Didion would have fared had she come to New York in 2015 rather than 1955. She is, after all, a writer for whom feelings (especially her own) are inherently unreliable sources. She assailed feminism’s “invention of women as a ‘class’ ” and wrote dismissively of the oppressed “Everywoman” who “needed contraceptives because she was raped on every date … and raped finally on the abortionist’s table.” She never got involved in the women’s movement, because, according to a friend, “she was beyond that.” Didion is, for all her sensitivity and curiosity, more than a little bit of a class snob. “Dunne joked about her archconservative values,” Daugherty writes. For much of her life, it seems, she voted Republican.

As new generations of artists and tastemakers grow hungrier for voices from worlds where mothers do not give teas and closets are not full of organdy tablecloths on long rollers, it’s easy to imagine a writer of Didion’s tastes and sensibility being called out in the blogosphere and in social media as fundamentally gifted yet fundamentally “problematic” (to use a term of the moment that Didion might have great fun with) in her politics and tone. For all her brilliance, she might be deemed too haughty to tolerate, the ultimate white girl.

But that would be both reductive and a total missing of the point. Didion may be a white girl to whom generations of white girls have been disproportionately drawn, but she’s one we—and all kinds of readers—have desperately needed. In the prefeminist 1950s and ’60s, we needed her to show that it was possible for a woman to put her writing first without apology or fanfare. In the let-it-all-hang-out ’70s, we needed her to be the disciplined storyteller who could deliver the goods while keeping herself at arm’s length. In the ’80s and ’90s, we needed her to separate the nation’s ghosts from the political machine. More recently, we needed her to grow old before us and, even amid unthinkable personal tragedy, show that it’s possible not only to remain visible and vital but also to remain unimpeachably, ineluctably cool. We still need her. Maybe now more than ever.