Kamala Harris was born in 1964, in Oakland, California, to young, married international graduate students. Donald Harris, her father, had emigrated from Jamaica to study economics, and Shyamala Gopalan, her mother, was an Indian diplomat’s daughter who was studying for a doctorate in nutrition and endocrinology and would become a breast-cancer researcher. Harris’s parents divorced when she and her sister, Maya, were young, and in their elementary-school years the girls lived with their mother, in the Berkeley flatlands, which was then a mostly black part of town. “My elementary school class,” at Thousand Oaks Elementary School, “was only the second class in my city to be desegregated through busing,” Harris writes in her new book, “The Truths We Hold.” Like Barack Obama, who is three years older than Harris and who entered politics around the same time, Harris was often described, in her early career, as having a background that operates as a kind of universal passport. In a profile of Harris that was published in 2007, in San Francisco magazine, the journalist Nina Martin wrote, “One of Harris’s Nob Hill friends thinks her Brahmin background accounts for her ease around wealthy, powerful people (her friends include Vanessa Getty, Cissy Swig, Susie and Mark Buell, and Nancy Pelosi). ‘A lot of people think, “Those people are too rich for me, I can’t be part of their world—they’re out of my fucking league,” ’ this friend says, adding that Harris never seemed to feel like she didn’t belong. ‘She just kept showing up.’ ”

Last week, Harris announced her candidacy for the Presidency of the United States. Her campaign has had a promising start: the day after the announcement, it had already raised $1.5 million in donations, and, last Wednesday evening, Rachel Maddow concluded an interview with Harris by saying, “Honestly, I think there is a good chance that you are going to win the nomination.” On Sunday, Harris held a kick-off rally in downtown Oakland, drawing a crowd of twenty thousand people. In the run-up to her announcement, Harris published her three-hundred-page memoir, which serves several purposes. One is to act on her mother’s advice, quoted in the book: “Don’t let anybody tell you who you are. You tell them who you are.” Another, more subtle purpose is to move her public persona out from the shadow of Obama and to begin to explain how the part of the Democratic Party that they both represent—not the progressive wing nor the moderate one but a liberalism that navigates between the two—has changed and what it has to offer now.

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As a memoirist, Harris does not permit herself much of a narrative arc. We read of the advice that she gets from her mother and the example set by her mother’s friends, but there is little doubt, conflict, or reassessment—none of the conventional components of a moral education. From her first extended appearance in her own memoir, as a junior prosecutor, Harris is more or less fully formed, an interrogative facsimile of the familiar, self-assured senator on the Judiciary Committee dais. When Harris begins a new job, she makes lists of short-, medium-, and long-term goals. When she started in the D.A.’s office, she recounts, she described herself as “a hard worker. A perfectionist. Someone who didn’t take things for granted.” It comes as a shock when she fails the bar. “The most half-assed performance of my life,” she writes, of her effort, still sounding disgusted with herself. Permitted to join the D.A.’s office on an interim basis, Harris overhears a colleague wondering aloud about her failure. It makes her feel like a fraud.

When Harris was a child, her mother had taken her to protests in a stroller; later, at U.C. Hastings, she had led the Black Law Students Association. So her decision to work as a prosecutor required, by her own account, some explanation. She writes (and here it is worth bearing in mind that the book was written as part of the rollout of a Presidential campaign, at a time when ideological battles on the left are especially fraught) that she knew from the outset that she wanted to follow a particular prosecutorial tradition—of Bobby Kennedy, of the Southern prosecutors who held to account the Ku Klux Klan. “When activists came marching and banging on the doors, I wanted to be on the other side to let them in,” she says. Two paragraphs later, Harris arrives at the crux of her point: “For too long, we’d been told that there were only two options: to be either tough on crime or soft on crime.” Her own wisdom, as a young prosecutor, “was that when it came to criminal justice, we were being asked to make false choices.”

The phrase “no false choices” recurs throughout the book; at one point, Harris describes it as a mantra. She seems to mean it mostly as a warning against ideological categorization: you may be told that you have to choose between seeing criminals as evildoers or as decent folks who have had bad luck, but that isn’t true—it is possible to take each case as it comes. “No false choices” is as close as “The Truths We Hold” comes to a central theme—Harris describes her adult life as a quest to be seen as something other than a member of a group. When she first ran for elected office, as a candidate for San Francisco District Attorney, in 2003, she was seen as part of the patronage machine of the majestic, transactional San Francisco mayor Willie Brown, whom she had dated years before; she told SF Weekly that Brown was “an albatross hanging around my neck.” (She does not mention Brown in her book).

In that campaign, Harris challenged an incumbent for whom she had worked, a famed left-wing patrician named Terence Hallinan. Harris matched his progressive positions—supporting medical marijuana and opposing the death penalty—and attacked him for administrative incompetence, for overseeing an office that could no longer reliably deliver convictions. (“She pretty much adopted my entire agenda,” Hallinan told the San Francisco Chronicle, after her win.) Within six months of her inauguration, a police officer was murdered. Harris announced that she would not seek the death penalty for the alleged killer and then sat at the officer’s funeral as Senator Dianne Feinstein, a former mayor of San Francisco and the most powerful Democrat in the state, unexpectedly called, from the pulpit, for the death penalty and received a standing ovation. Harris did not budge, even as her conflict with Feinstein became a national story. In her book, Harris mentions some of these episodes only in passing, and others not at all, but together they suggest a pointed interest in political independence.

When politicians tell their own stories, they often emphasize the hardscrabble parts, even if those took place long ago. Harris, winningly, does not. Raised for accomplishment, she achieved success quickly, and she suggests, in glimpses, a comfortable personal life. She does not just cook beef stew but Alice Waters’s recipe. Her engagement—to Doug Emhoff, the Los Angeles-based managing partner of a law firm, whom she married in 2014—takes place between a professional trip to Mexico and a personal one to Florence. Harris describes her frustration when her husband, who is white, is relaxed on the customs line while she is on edge and prepared, recalling all the times her brown-skinned mother was followed around a department store with suspicion.

But in this book, at least, she writes much more about racial and gender bias in the lives of others than she does in her own. In the Bay Area she describes, progressivism and power overlap. The local activist whom she hires to run her signature reëntry program, in San Francisco, has already won the MacArthur Fellowship. Her beloved younger sister, Maya, becomes the executive director of the Northern California A.C.L.U. and, eventually, a key progressive-policy adviser for Hillary Clinton’s campaign. Maya’s husband, Tony West, becomes the third-ranking official in Obama’s Department of Justice before becoming the general counsel at Uber. One illusion cast by professional life in a cosmopolitan city is that institutions of power and idealism can be intertwined, because the same people move neatly between them—that the choice between them is a false one.