One of those transformative moments comes during Obama's undergraduate days, after he had given a well-received speech urging the university to divest from South Africa. A black friend, Regina, praised his talk, but Obama cynically denied that it had any meaning, saying he just did it for the applause and that it wouldn't change anything. Regina retorted that he was selfish and shallow -- "It's not just about you" -- and angrily left. Left alone, Obama suddenly realized she was right. His mother had told him the same thing, but he had rejected it, putting it down as "white" truths. "Who told you that being honest was a white thing? ... You've lost your way, brother. Your ideas about yourself -- about who you are and who you might become -- have grown stunted and narrow and small.

"How had that happened? I started to ask myself, but before the question had even formed in my mind, I already knew the answer. Fear ... The constant, crippling fear that I didn't belong somehow ... that I would always remain an outsider, with the rest of the world, black and white, always standing in judgment."

Then Obama modulates into something like a vision, at once real and transcendent. He imagines the face of Regina's grandmother, "her back bent, the flesh of her arms shaking as she scrubs an endless floor. Slowly, the old woman lifted her head to look straight at me, and in her sagging face I saw that what bound us together went beyond anger or despair or pity. What was she asking of me, then? Determination, mostly. The determination to push ahead against whatever power kept her stooped instead of standing straight."

And then, an even larger vision. "The old woman's face dissolved from my mind, only to be replaced by a series of others. The copper-skinned face of the Mexican maid, straining as she carries out the garbage. The face of Lolo's mother [Lolo was Obama's Indonesian stepfather] drawn with grief as she watches the Dutch burn down her house. The tight-lipped, chalk-colored face of Toots [Obama's white grandmother] as she boards the six-thirty bus that will take her to work. Only a lack of imagination, a failure of nerve, had made me think that I had to choose between them. They all asked the same thing of me, all these grandmothers of mine."

Finally, the lesson, to be carried forward: "My identity might begin with the fact of my race, but it didn't, couldn't, end there. At least that's what I would choose to believe." Through a long and arduous search for blackness, Obama arrived at humanity.

In a certain way, Obama's odyssey in "Dreams From My Father" mirrors that of the boy hero of the greatest novel America has produced -- a book that is also about race, and the terrible wound that slavery left on this country and all its people. Huck Finn has been abandoned by his father, a bitter, drunken racist, and has to make his way through the world alone. But actually, he is not alone: a fugitive, he drifts down the Mississippi River, the river that runs through America's heart, with Jim, a runaway slave. And in the course of their journey, the wise and kindly Jim becomes Huck's father -- and, by implication, the father of every American. The pathos of Twain's masterpiece is it redeems our nation's dark history by allowing the despised slave to raise, and ultimately teach the meaning of life to, the lost and innocent boy.

Obama's quest is identical, except the colors are reversed. In search of an absent black father, he tries to become authentically black. And it is only when he learns that his father is all too human that he finally comes to understand that he is the child of both black and white, and ultimately of everyone, of all colors. "All these grandmothers of mine."

The man who emerges from this book has the integrity, the wisdom, the "dogged strength," to fight for a reborn America. And he also represents something larger than himself: He embodies hope. But that hope will only become real if the American people make it real. For hope is just a vessel. You have to fill it.