It may sound odd to suggest that Sissy Spacek has long been underrated as a performer. She has been nominated six times for the Best Actress Oscar, winning the prize for her transformative turn as Loretta Lynn in 1980’s Coal Miner’s Daughter. In an industry that tosses aside its leading ladies once they turn forty, the 62-year-old actress has sustained a four-decades-long career, often managing to connect with immensely gifted directors—Alan Rudolph (Welcome to L.A.), Robert Altman (3 Women), Costa-Gavras (Missing), and Bruce Beresford (Crimes of the Heart)—just when their talent was reaching full flower.

Yet in a strange way Spacek, whose new memoir, My Extraordinary Ordinary Life (Hyperion, $26.99), arrives this month, has never entirely escaped the shadow of her first major roles. She was chilling as the impressionable girl who falls in love with a murderous drifter in Terrence Malick’s Badlands (1973) and as the ugly duckling humiliated by her classmates on prom night in Brian De Palma’s Carrie (1976). But she was dogged by the vaguely condescending suggestion, at least among some critics and viewers, that she lacked the range of her most lauded peers, Jessica Lange and Meryl Streep. That she was best when she was basically playing herself.

In his entry on the actress in A Biographical Dictionary of Film, cinema historian David Thomson singled out her “authentic sense of rural life and uneducated ways,” presumably acquired during her upbringing in the bucolic East Texas town of Quitman. In her review of Carrie, New Yorker critic Pauline Kael wrote that Spacek “uses her freckled pallor and whitish eyelashes to suggest a squashed, froggy girl who could go in any direction.” (From the files of damning people with the strangest of praise, Kael then went on to compare the actress to a fetus.)

That’s one of the reasons My Extraordinary Ordinary Life is so valuable: it makes evident, once and for all, the depth of intelligence and sheer imagination that she has poured into her work. Writing about Badlands, Spacek describes art director Jack Fisk (who later became her offscreen husband) decorating the set with knickknacks that he imagined the character of Holly might have owned. Spacek then used those knickknacks to help find her way into the character. “I’d lay on Holly’s bed and hold these gems in my hands,” she writes, “feeling like I was Scout in To Kill a Mockingbird and Boo Radley was leaving me gifts in the hollow oak tree.”

Later in the volume, Spacek writes about poring over a book of Bible illustrations by Gustave Doré to create Carrie’s body language; trailing Loretta Lynn for months and performing alongside her at the Grand Ole Opry to prepare for Coal Miner’s Daughter; and working herself into an emotional frenzy for hours each day before the cameras rolled on the set of Missing, in which she plays a woman searching for her kidnapped husband in Chile.

Certainly Spacek is someone deeply in touch with her roots (and, indeed, the memoir is penned in folksy, aren’t-I-just-the-luckiest-thing prose that may buttress perceptions that she’s a small-town naïf). But the larger portrait that emerges is one of a thinking actress, a technician whose air of naturalism is exhaustively cultivated.

Could she have pulled off, say, the mixture of freewheeling sensuality and doomed glamour that Lange brought to Blue Sky or the acidly comedic timing of Streep in The Devil Wears Prada, to cite just two parts I suspect most filmgoers could never have imagined Spacek playing? That’s a movie-geek parlor game question with no answer. Yet to anyone who might argue that Spacek can venture only so far from her “rural” roots or that she’s capable of playing only a certain kind of beleaguered, “uneducated” woman, I’d advise taking a closer look at a few more of her deeply impressive turns, which are touched on just briefly in the memoir.

There’s the tender, romantic yearning she showed us in the underrated Violets Are Blue (1986), directed by Fisk, in which she plays a woman trying, against her better judgment, to win over a married man. There’s the resplendent ballbustery she showed in a very funny guest run as a powerful lobbyist on HBO’s Big Love (2010). And there’s the quicksilver ferocity of what I regard as her finest performance, in Todd Field’s In the Bedroom, as a Maine school choir instructor whose son has been murdered. Near the end of the picture, the son’s surviving girlfriend, played by Marisa Tomei, attempts to comfort Spacek’s character. Infuriated and inconsolable, Spacek unleashes a slap to Tomei’s face so unexpected that it inspired dozens of gasps in the theater in which I first saw the film.

I hate to imagine, for the sake of poor Tomei’s battered cheek, how many retakes it took to capture on film a moment so precise and powerful. But therein rests the genius of Sissy Spacek, who—whether playing hicks or urbanites, horror queens or heartbroken Southern belles—makes it look like it simply happened.