Never has there been an American President who revealed so much of himself prior to taking to office, or launched upon such a public quest for personal discovery.
By his mid-forties, President-elect Obama had authored two memoirs of his scattered life, both of which became global best-sellers. His search for identity has been instrumental in his upward journey towards power.
Yet for all his "age of Oprah" candour, and for all the 400-plus pages of his beguiling autobiography, Dreams from My Father, to many he remains a frustratingly elusive and enigmatic figure.
The Obamas will make history when they move into The White House
Who precisely is Barack Hussein Obama, a politician who defies neat encapsulation?
The back-story begins in a suitably exotic location: Hawaii. Back in the late-1950s, America's most newly-minted state was the meeting place for his African father, Barack Hussein Obama Sr, and his American mother, Ann Dunham.
A talented and exuberant economist who had won a scholarship to the University of Hawaii, Barack Sr came from the shores of Lake Victoria in Kenya. His mother, Ann, was an "awkward, shy American girl", from Wichita, Kansas. Though Barack Sr was five years her elder, they met in a Russian language class and quickly fell in love.
Black father, white mother
The couple were married on 21 February 1961, a month after John F Kennedy took the presidential oath of office. Less than six months later, they celebrated the birth of a child, Barack Hussein Obama Jr.
He was the product of what was then a rarity in post-war American society: a mixed-race marriage. As Barack Obama himself wrote, his father was as "black as pitch", while his mother was as "white as milk".
Certainly, there are clues to Obama's personality in the unorthodox backgrounds and personalities of his parents. His father had come to the University of Hawaii as its first black student, and became the president of the International Student Association. He was known for his rich speaking voice, strong opinions and a magnetic personal charisma.
His mother was an only child, who was christened Stanley Ann because her parents yearned for a boy. As a schoolgirl and student, she was known for her quick wit, feisty intelligence and expansive vocabulary.
The marriage did not last long, but then Barack Sr hardly fitted the mould of the reliable husband. Before arriving in Hawaii, he had been married already to a local Kenyan woman, who mothered four of his children (he lied to his new wife, Ann, that he had arrived in Hawaii a divorcee).
Then, when Barack Jr was still a toddler, he decided to take up a scholarship at Harvard, turning down a more financially generous offer from New York University which would have supported the whole family. So Ann and young Barry, as he was then known, remained in Hawaii. And thereafter, Barack Obama Sr made only one more appearance in his son's life, visiting him in Hawaii when he was aged 10.
The break-up of his parents' marriage set-up the next episode in Barack Obama's life: his years in Indonesia.
Ann met another foreign student at the University of Hawaii, an Indonesian by the name of Lolo Soetoro. They lived as a family for two years in Hawaii, before leaving for Jakarta in 1967.
Within six months, Barry had learnt Indonesia's language and was being awoken by his mother at 4am each morning so that she could give him additional English lessons before school. Perhaps his thirst for self-improvement, and his fierce self-criticism, stem from those pre-dawn lessons.
There were other formative influences. His step-father was a Muslim, though he followed a brand of Islam, according to Barack, "that could make room for the remnants of more ancient animist and Hindu faiths".
Certainly, Barack appears to have been impressed by the broad experience and worldliness of his stepfather. "Not just how to change a flat tyre or open in chess," he later wrote. "He knew more elusive things, ways of managing emotions I felt, ways to explain fate's constant mysteries."
Barack Obama's way with words is a "vital political tool"
Perhaps Obama's steady-state temperament and capacity for emotional detachment come from his stepfather. Once, after Barry had been bullied by an older boy, Lolo also taught his adopted son to punch above his weight, another useful lesson for his future career in politics.
Indonesia also exposed Barack to the kind of Third World suffering that may well have aroused his social conscience. In Dreams from My Father, he spoke of the sorrowful faces of drought-hit farmers, and of the beggar who came to his door with a gaping hole where his nose should have been.
More importantly, perhaps, Obama became more overtly aware of his skin colour. On the television shows imported from America, he noticed that the black character in the hit series Mission Impossible spent all his time underground and that "there was nobody like me in the Sears, Roebuck Christmas catalogue".
His racial consciousness had stirred.
Aged 10, Barack was sent back to Hawaii to complete his education - in Indonesia, he had spent two years at a Catholic school and two years at a Muslim school - while his mother remained in Jakarta.
During this unsettled period of his life, he was raised by his maternal grandparents, Stanley and Madelyn, his beloved Toot who died on the eve of his election.
It was not the happiest of homecomings. On his first day at his new school, there were titters in the classroom when the teacher read out his exotic-sounding name; and he was frosty towards a girl called Coretta, the only other black pupil in his grade.
Search for identity
"From the first day, we avoided each other but watched from a distance," he wrote later, "as if direct contact would only remind us more keenly of our isolation."
Later, he experienced the rare thrill of racial and familial pride, when his father, Barack Sr, visited Hawaii and delivered a speech before his class. "Your dad is pretty cool," said one of his classmates, who earlier had asked a question about cannibalism.
After that proud day in class, Barack Obama was abandoned once more by his father, and thereafter his high-school years were wracked by confusion and self-doubt.
Chicago proved the making of him. Ultimately, it was where he found Jesus, his wife, Michelle, and his sense of political mission
"I was trying to raise myself to be a black man in America," he wrote, "and beyond the given experience of my experience, no one around me seemed to know exactly what that meant."
This was the period in his life when he started living out what he called a caricature of black male adolescence. He loved playing basketball, drank and experimented with narcotics - pot, cocaine (when he could afford it), but not heroin. Drugs seemingly helped push the question of his identity out of his mind.
At the same time, he seemed aggrieved that Hawaii placed him so far away from the more common black experience: of growing up in the post-segregation South or the slums of Harlem, Watts, Detroit or the South Side of Chicago.
Though his mother had taken a keen interest in the emerging civil rights movement, he had no direct connection with the struggle for black equality. Tellingly, then, he was attracted to the writings of Malcolm X, with their emphasis on black nationalism, self-discipline and self-reliance, rather than the less confronting essays of the Reverend Dr Martin Luther King Jr, with integration and racial harmony.
After graduating from high school, he enrolled at Occidental College in Los Angeles, where there were enough black students to form a "tribe". Two years later, he transferred to Columbia University in New York. Columbia is Ivy League, but it was the ethnic flavour of New York that drew him east.
"I'd at least be at the heart of a true city," he recalled, "with black neighbourhoods in close proximity."
It was in the black neighbourhoods that Barack Obama found his metier, working as a community organiser.
On graduation from Columbia, he worked for a year in the corporate sector before joining a public interest group in New York, which campaigned for upgrades to the city's subway system. Then he left for Chicago, drawn partly by the recent election of a black mayor, Harold Washington. There, he joined the faith-based community action group, the Developing Communities Project.
Chicago proved the making of him. Ultimately, it was where he found Jesus, his wife, Michelle, and his sense of political mission.
Barack Obama has referred to his wife, Michelle, as "the love of my life"
In the city's demoralised South Side, he worked on job training programmes and local housing projects. His grass roots campaigns soon brought him into contact with the Reverend Jeremiah Wright, an exuberant local preacher.
The first time that Barack Obama listened to one of the preacher's sermons, he broke down and wept. It was entitled The Audacity of Hope, which became the title of Barack Obama's breakthrough speech at the Democratic Convention in 2004, and the book which launched his presidential campaign.
During his initial three years in Chicago, Obama mused with friends about whether he should become a preacher, a journalist or a novelist. But ultimately he decided to pursue a career in law, and gained a place at the prestigious Harvard Law School.
African and American
His years at Harvard first brought him to the attention of the national press, when he became the first black President of the legal journal, the Harvard Law Review. It was heralded as a major racial first.
His time at Harvard Law School also brought him to the attention of his future wife, Michelle, an attorney with an elite Chicago legal firm where Barack worked as a summer associate. The descendant of slaves, whose undergraduate dissertation at Princeton focussed on the subject of black advance, Michelle was much more firmly rooted in the black tradition.
Barack Obama is sometimes called an African and an American, but not an African-American. By contrast, there is no doubting his wife's bloodline, since it reaches back to the pre-Civil War American South. The couple were married in 1992. Perhaps her background provided some of the flint for their relationship.
Success at Harvard led to Barack Obama's first book deal, and Dreams from My Father. It also brought lucrative offers to work at high-end corporate law firms. But Barack Obama decided to return to Chicago, where he taught constitutional law at the University of Chicago Law School and resumed his community activism.
Throughout this period, he became more politically focused and active.
In 1992, he ran a voter registration campaign which helped the black candidate, Carol Moseley Braun, win election as a US Senator for Illinois (thus becoming the first African-American woman to claim a seat in the Senate).
Michelle's connections - her best friend is the daughter of the civil rights leader, Jesse Jackson, and she had worked for Chicago's powerful mayor, Richard M Daley - also brought him into closer contact with the city's Democratic political elite.
Now, Barack Obama displayed a more calculating side of his character: a sometimes highly strategic choice about his political friends and mentors, which also served him well in the US Senate.
Crowds gathered throughout the world to honour Mr Obama's big win
With the contacts necessary to succeed in the hot-house climate of Chicago politics, Obama ran in 1996 for a seat in the Illinois state Senate, which included parts of the South Side and the more fashionable Hyde Park neighbourhood.
Showing the harsher, and more ruthless, side of his political personality, he defeated the popular Democratic incumbent and former ally, Alice Palmer. The veteran Illinois politician had first decided to step down but then decided to re-enter the race. Obama campaigned successfully to get her name removed from the ballot.
Lure of Washington
Back then, of course, Jeremiah Wright was the most useful of political allies. So, too, was Tony Rezko, a Chicago-based political fund-raiser convicted this year of fraud and bribery. So perhaps it is no coincidence that his years as a Chicago politician get the least attention in his memoirs, for they reveal less attractive sides of his political personality: hard-nosed calculation combined with eager ambition.
Sure enough, Washington DC soon became the target of his ambitions. In 2000, after just four years in the Illinois State Senate, he tried to win the Democratic primary in one of Chicago's US congressional seats. But he was defeated by the former Black Panther, Bobby Rush, another popular incumbent.
Four years on, Barack Obama won his party's nomination to fight for the US Senate, a campaign which brought him into contact with the then Senator John Kerry. So impressed was Kerry with the telegenic, 40-something Chicago candidate that he invited him to deliver a keynote speech at the Democratic Convention.
Before a prime-time audience, Obama deployed his most vital political tool: his mesmerising power of speech. And fittingly for a politician who had shown such a preoccupation with his own personal identity, the main subject of his address was America's search for itself.
"There is not a liberal America and a conservative America," he proclaimed. "There is a United States of America. There is not a black and white America and Latino America and Asian America - there's the United States of America. The pundits like to slice-and-dice our country into red states and blue states... but I've got news for them, too. We worship an 'awesome God' in the blue states, and we don't like federal agents poking around in our libraries in the red states."
Launching his quest for post-partisanship, he jettisoned the angry language of polarization, and rejected the rhetorical and political constructs of the Sixties.
Crucially, he also saw the political value in deploying his wide-ranging biography, and spoke of how his white grandfather had served in George Patton's army and how his black grandfather cooked for his British colonial masters.
His quixotic personal history became his message. "I stand here today, grateful for the diversity of my heritage," he said, "knowing that my story is part of the larger American story." That speech in 2004 arguably provided the most important turning point of the 2008 campaign. And the rest is epoch-changing history.
Barack Obama has won the presidency by persuading more than 50% of the US electorate that his story resonates with their own. With poetry and poise, he has given voice to a personal history that is as messy, complicated, confounding and inspiring as the country he now leads.
Who is Barack Obama? For many of his admiring supporters, he is the very idea of modern-day America.
Nick Bryant, a former BBC Washington correspondent, is the author of The Bystander: John F. Kennedy and the Struggle for Black Equality