WHAT LIPS MY LIPS HAVE KISSED: The Loves and Love Poems of Edna St. Vincent Millay.

By Daniel Mark Epstein. Henry Holt. 300 pp. $26

A poem’s "I" can hypnotize us into believing we have seen through the portals of a poet’s secret anguish. That’s commonly an illusion, but not in the case of Edna St. Vincent Millay. Epstein, a poet who has written biographies of Aimee Semple McPherson and Nat "King" Cole, persuasively links themes in Millay’s life to themes in her verse, including guilt, longing, rituals, religious defiance, and, of course, eroticism.

Millay (1892–1950) grew up in Maine with two younger sisters and a divorced, hardened mother, Cora. To support the impoverished family, Cora often took nursing jobs out of town, which left frail Vincent, as she was known, as de facto parent. The upbringing sparked an uprising of sorts, hushed but heartfelt. "I guess I’m going to explode," teenage Vincent confided to her diary.

(Epstein enjoyed nearly unprecedented access to the poet’s papers at the Library of Congress.) In another entry, she laments her household responsibilities and longs for carefree "jump-rope and hop-scotch days." At 19, she wrote that "I have been ecstatic; but I have not been happy"—a passage the biographer deems key to understanding Millay’s personality.

While still living at home, Millay gained a measure of local renown through her poetry. Her fame spread vastly with the poem "Renascence," published in a collection of new work by some 60 poets in 1912. One reader maintained that the book’s description of Millay had to be a hoax: "No sweet young thing of 20 ever ended a poem precisely where this one ends; it takes a brawny male of 45 to do that." Millay went on in 1923 to win the Pulitzer Prize in poetry, the first woman to do so. By her early thirties, she had established herself as America’s best-known poet.

In 1923 she wed the Dutch-born Eugen Boissevain; the marriage proved long and lenient. "She must not be dulled by routine acts; she must ever remain open to fresh contact with life’s intensities," declared her adoring husband, who graciously disregarded her periodic love affairs. The affairs, like much else in her life, found their way into her witty, carefully crafted diary entries, and then into her poetry. Through the diaries, Epstein traces obvious and pure links between the poet’s feelings and her verse.

Millay yearned for the respect of the critics as well the devotion of the public, but she lost both with Make Bright the Arrows (1940), a heavy-handed tribute to the Allies. "There are a few good poems, but it is mostly plain propaganda," she acknowledged to one correspondent. She hoped reviewers would at least single out the good poems, but they didn’t. Her reputation never recovered, and morphine, alcohol, and agoraphobia overshadowed her final decade.

Shifting fashions in poetry further dulled her reputation. Millay’s great strength was fiery passion, not the calculated perplexity of Eliot and Pound. Today, in an age dominated by narrative poems in the third person, her first-person confessional verse can seem sentimental. But don’t be surprised if Epstein’s vigilant investigation sparks a Millay renascence—a new wave of admiration for the many costumes of her erotic sovereignty.

—Allison Eir Jenks