Ernest Hemingway is the macho face of 20th-century prose. His birth in 1899 marked the arrival of a man who wanted to dissociate literature from the taint of femininity it had acquired under the influence of Oscar Wilde and align it instead with a kind of hairy masculinity. Lilies and wallpaper were finished. In their place? Blood, battle, sex, hunts, death. Manly things. And to treat manly things properly, literature would require an appropriately manly style. Out with girly adjectives, rapt similes, elaborate metaphors, ethereal ruminations. In with curt observation, plain sentences, icy repetition. Wilde thought that all art had to be useless. Hemingway knew better: It was a duty. And it had, moreover, to be “true.”

These beliefs, which placed Hemingway under the obligation to write what he experienced and experience what he wrote, help to account for the intensity with which the obsessions and traits we find in his work occur in his life. To encounter Hemingway as an adult was to be faced with a man whose appetite for supposedly masculine pursuits was so assiduously cultivated as to border on parody. He liked to shadowbox while walking down the street. He would routinely chivy his friends into the ring in order to engage in tests of strength. He developed obsessions with bullfighting, hunting, heroism, warfare, bodily exudations (blood being a particular favorite). He nursed a lifelong fear of being thought gay. He could be cruel and violent to women.

In her balanced and well researched new biography, Mary V. Dearborn makes use of a host of hitherto overlooked material — much of which she discovered in a collection of his mother’s papers held by the University of Texas. She explores what made Hemingway cultivate the image he did, and whether there is more to her subject than such a portrait allows. The result is a work in which “the Hemingway legend” — a phenomenon in which Dearborn has “no investment” — emerges more or less intact. Only here it is presented with an array of qualifications that cast Hemingway as a more troubled, complex and tragic figure than most previous biographies have allowed.

Dearborn begins her examination of Hemingway’s sensibility by attending to the curiosities of his childhood at Oak Park, Ill. His father was a puritanical doctor with a love of the outdoors (he taught his son how to hunt), a propensity for violence and severe manic-depression (he would eventually commit suicide). His mother could be a loving parent, but she was weirdly controlling and capable of alarming episodes of irresponsibility. When Hemingway was a baby she would hold him in her arms while firing a pistol (she once reminded him how he “always loved to cuddle in my neck when the gun fired”). And she insisted on treating him and his sister (18 months his senior) as twins, dressing them as both boys and girls as her whim dictated. Dearborn considers this habit a source of Hemingway’s subsequent (and largely private) preoccupation with gender fluidity, of his concomitant insecurity about his masculinity, and of the hatred he would feel for his mother in later life.

Following high school and a series of journalistic apprenticeships, these formative influences, helped along by his recklessness and desire for action, would recur in Hemingway’s life with devastating force. Dearborn guides us engagingly through his traumatic experiences working for the Red Cross in the Great War (during which he was shot and almost killed); his attempt to establish himself as a writer in Paris in the 1920s; the suicide of his father; his experiences in the Spanish Civil War; his involvement spying against the Nazis (and for the Russians) during the Second; his literary success; his marriages to his four wives; his debilitating head injuries; his boozy retreat to a Cuban finca; his collapse into the madness, dipsomania and infirmity that would lead to his suicide in 1961.

As Dearborn tells his story, we see Hemingway comport himself with compulsive nastiness, congenital dishonesty and staggering petulance. If he wasn’t getting his way with women, he would threaten to commit suicide. If a friend had helped him with a literary matter (F. Scott Fitzgerald being the most notable case in point), that friend would almost always be disposed of. If his wives failed to behave with suitable deference, they would be subjected to verbal and physical abuse. Minor slights were routinely treated as gross transgressions. Animals were both revered and treated with terrible cruelty. He once boasted of shooting a dog in such a way as to ensure it would take days to bleed to death.

Seldom does Dearborn soft-pedal such behavior. But she does situate it in the context of Hemingway’s struggle with an increasingly aggressive form of manic-depression, and of the alcoholism, paranoia and insecurity that exacerbated and accompanied the condition. She quotes Zelda Fitzgerald to the effect that everybody regarded him as self-evidently “bogus.” “Nobody,” said Zelda, “is as male as all that.” And she was right. In private, as Dearborn shows, Hemingway would talk with his wives about his desire to transgress conventional gender boundaries — about his wish to be their girls. And they would sometimes allow him to explore the impulse.

Dearborn explores these corners of his sensibility more fully than previous biographers, and she does so with subtlety and insight — qualities that are also present in her discussions of Hemingway’s work. She is refreshing when she describes “Death in the Afternoon” as “rambling and sometimes inane.” And she can be funny, too, as when she documents the stylistic infelicities — the relentless use of “truly,” “thee,” “thou” — of “For Whom the Bell Tolls.”

But Dearborn is not always convincing when writing admiringly. Her claim that Hemingway was uniquely adept at transforming life into literature is unverifiable, and vulnerable to the example of countless other writers (Saul Bellow among them). And her prose can be inattentive: We learn that Hemingway had his “heart in his mouth”; “was spoiling for a fight”; “jumped at the chance” to move to Chicago where he discovered that the best writers must learn “to push the envelope.”

On the whole, though, this is an admirable, affecting and thoughtful biography, distinguished by a scrupulousness and good sense that animates its subject with vigor. Hemingway once said that to capture real life on the page it is necessary to include “the bad and the ugly as well as the beautiful.” Dearborn has taken that observation seriously. In doing so she has produced the most fully faceted portrait of Hemingway now available. And moved us closer to an understanding of his love, and his fear, of the truth.

Matthew Adams is a British writer who contributes to the Guardian, the Times Literary Supplement and the Irish Times.