Eleanor Roosevelt's motto was "you must do the thing you think you cannot do," an essential creed for a woman who survived setbacks that would crush most ordinary mortals. David Michaelis' new one-volume biography of Roosevelt sets out to solve the riddle of how this extraordinary woman survived and surmounted her challenges.

There were so many. The loss of her father to alcoholism and suicide, and her mother's death soon after. Her discovery, after bearing Franklin Delano Roosevelt six children (five lived), of a packet of love letters from his mistress Lucy Mercer. Her husband's crippling polio. The dismissal of her prodigious talents because she was a woman, and the cruel taunts about her appearance.

Depression and alcoholism ran in Eleanor Roosevelt's family and she might have yielded to despair, but she turned every obstacle into a launchpad. She felt utterly betrayed by Franklin, but she became his essential political partner in his pursuit of the governorship of New York, then the presidency. She broke the mold of a politician's wife and became a public servant and social activist in her own right. She wrote a daily newspaper column — 800 words a day, six days a week — for 26 years. She worked as an unpaid government adviser through the Depression and the war years, championing the stressed and the dispossessed:

"It was she, not he, who really invented the New Deal," wrote H.L. Mencken. Postwar, after her husband's death, she became the first chairperson of the United Nations Commission on Human Rights.

Reading her story, the overriding question for readers in our fraught times might well be: Where did Eleanor get her grit? But Michaelis seems more preoccupied with her needs, as, trapped in a passionless marriage, she chased affection wherever she could find it, whether in her love affair with journalist Lorena Hickok or her close and at times passionate friendships. Though journalist Martha Gellhorn once said that Eleanor was "the loneliest human being I ever knew in my life," by the end of her life Eleanor Roosevelt was ranked in a Gallup poll as the most admired woman in America. How did she summon the strength that enabled her to survive abandonment and betrayal, then carry on?

Michaelis does a credible job at re-creating the traumatic history that the Roosevelts both endured and shaped, but his informal style presents challenges. He has a maddening habit of presenting a character without introduction, then explaining who they are several pages later. Characters appear, then leave the narrative with the briefest of explanations. Keep your smartphone handy.

Perhaps there is too much of Eleanor Roosevelt's life to get it all in one book — it took Blanche Wiesen Cook three volumes to cover it. Perhaps Gellhorn said it best: Roosevelt was "something so rare that there's no name for it, more than a saint, a saint who took on the experiences of everyday life, an absolutely unfrightened selfless woman whose heart never went wrong." How did she remain so straight and true? Michaelis' zeal for his subject is apparent, but in the end the mystery of what made this astounding woman persist remains elusive.

Mary Ann Gwinn is a book critic in Seattle.

Eleanor
By: David Michaelis.
Publisher: Simon & Schuster, 704 pages, $35.