You can see him in action on the back of the book jacket, working a crowd with two hands, smiling, sucking up the attention, devouring the love. And it's fully reciprocated: The people are straining to reach him, to touch him, to receive his presidential validation. Bill Clinton's world has a radial symmetry, like a flower, with his white thatch of hair popping out at the center.

This was the life he wanted, the one he constructed, the one he recounts in 957 pages. "My Life" has neither a subtitle nor subtlety, but it's surely a very American tale, a story of a kid who bounded from nowhere into the history books, erupting from the land like a force of nature (or a natural disaster, some might argue).

He was not a prince of the political universe like the guy who would one day be his vice president, or the fellow who would be his successor. Clinton was not anointed from on high. He never knew his dad, had a lush of a stepfather who once nearly gunned him down. He was pudgy. Talked too much. Silly clothes. "I was a fat band boy who didn't wear cool jeans."

And now he's in the books as the 42nd president, two full terms, notwithstanding a wee bit of impeachment tarnish.

Historians will judge his merit as a president, and readers can decide for themselves whether "My Life" is as interminable as many reviewers suggest, but in any case the million-selling memoir adds more data to one of the great mysteries of America: Why do some people defy all the probabilities of the world and wind up as the president of the United States?

Political success at the highest levels may require such things as intelligence, cunning, idealism, an ability to read other people, an instinct for when to attack and when to retreat, and so on, but you usually don't get anywhere near the White House without boodles and boodles of drive. You need more than your garden-variety vim and vigor. You need to ache for greatness. You need to crave distinction. Often it is referred to in political circles as "fire in the belly."

This is the norm for presidents. They can sprout from the most depleted soils, and flower brilliantly, as though what flows in their veins is not the same kind of juice that sustains everyone else.

"They're not normal people," says Richard Shenkman, author of "Presidential Ambition: Gaining Power at Any Cost." "All of these presidents seem to have extra hormones. . . . They are not normal in their appetites, in their passions, in their drives, in their willingness to take on great burdens in service to their ambitions, and to sacrifice almost everything on the altar of their ambitions."

Their great attribute -- drive -- can be their downfall as well. Their success can be intoxicating. They sense they are invulnerable. They overreach. They take unneeded risks. They become the leaders of their own cult of personality.

"Greatness is always at the edge of pathology," says Allan Lichtman, a historian and presidential scholar at American University. "To drive yourself that hard to make the most difficult possible decisions, to put millions of the world's people at risk, you have to be so far removed from the normal that you are always at the edge of the pathological. There is always the possibility of a great leader falling over that abyss."

Americans are historically an ambitious people, driven to improve their surroundings, to light out for new territory, to invent new tools for wringing sustenance from the earth. It has been a nation of warriors, explorers, rock-ribbed laborers. The notion that anyone can be anything, can rise above the commonplace, is deeply rooted, and nothing captures that notion better than the belief that any child can grow up to be president of the United States.

Biographer Robert A. Caro tells the story of the teenage Lyndon Johnson, skinny, poor, working on a road gang in the Hill Country of Texas, slinging a pick, shoveling gravel, driving a two-handled scoop called a fresno, pulled by mules with the reins wrapped around his torso -- brutally difficult labor. And yet Johnson would stand around a barrel fire in the cold of winter and say to his buddies, "I'm going to be president."

The log-cabin myth is overstated. Relatively few presidents were truly impoverished. Many were middle class at the very least, some quite rich. But they still have tended to vastly outpace their peers. Jimmy Carter's father was a successful farmer, but who would have guessed that a kid growing up in the cotton and peanut fields near Plains, Ga., would someday be president?

Most presidents showed exceptional drive at an early age. Abraham Lincoln ran for the legislature in his early twenties. Franklin Delano Roosevelt ran for vice president before his 40th birthday. George Washington was a military hero in his early twenties, fighting the French in the woods of Pennsylvania. Washington didn't stumble into greatness but worked for it, relentlessly trying to improve himself, to rise above the "common run" of men.

The current occupant of the White House is an unusual case. He once had the distinct advantage of being able to refer to a president of the United States as "Dad." No one has ever accused him of being a prodigy. Other kids at the dinner table seemed more likely heirs to Dad's political success. After his 40th birthday he had a religious rebirth, stopped drinking, got a steady, good-paying job (governor of Texas) and soon was tapped on the shoulder and told he might be the next president of the United States.

"You cannot begin to understand George W. Bush without understanding the born-again mentality. He started his life again," says Lichtman.

Clinton and Bush have different sorts of drive. Lichtman uses the Isaiah Berlin metaphor of the fox and the hedgehog. Fox knows many things, hedgehog knows one big thing. Clinton, the ultimate fox, dashes from subject to subject promiscuously; the hedgehog Bush knows only that he's going to kick some serious terrorist butt.

"I do think he believes he has a certain messianic mission, and it was provided to him after 9/11," Lichtman said.

Being psychoanalyzed from a distance is an occupational hazard for presidents. In "My Life," Clinton joins the psychobabble game with statements about his compulsion for secrets, his repressed anger, his "parallel lives." What he never quite explains is where his belly fire comes from. His flamboyant mother with the painted-on eyebrows? His father, who drowned in a ditch three months before he was born? His youthful pain and embarrassment? If being a fat band dweeb drives someone to become president, why hasn't the White House been full of tuba players?

Shenkman, reached in Paris, said in an e-mail that no single explanation accounts for presidential ambition:

"In some cases, like that of [John Quincy] Adams, it is a matter of familial obligation; the son feeling that the only way he can prove himself is by achieving the position of the father.

"In other cases it seems to have been a childhood drama of some kind that inspires individuals to seek power in the public arena to compensate for some weakness in their private life. Ronald Reagan and Bill Clinton fall into this category; so did Richard Nixon and Teddy Roosevelt.

"All four in their childhoods were viewed as physically weak, unable to compete in sports like their peers. Reagan had terrible eyesight. Clinton was fat. Nixon was slight. Teddy was asthmatic. Obviously they enjoyed other advantages which helped them along the path to power. But their physical weaknesses seem to have inspired them to achieve, and that very powerful sense of weakness overcome was a great driver of their careers."

In Clinton's memoir he says that by the age of 15 he wanted to be an elected public official. The journalists who covered Clinton in his first presidential campaign in 1992 knew he was a different sort of creature: He wanted it more than everyone else. He campaigned harder, stayed up later, shook more hands, tried to overcome questions about his fidelity and military draft record by promising the voters he'd stick by them till the last dog dies.

Clinton's life would exhaust any normal person. The man doesn't sleep much, has his fingers in everything (including some things he should have left alone), has a million friends and always wants more. He's socially insatiable, mentally tireless. As a young man he spent drab, cold February in Oxford reading "hundreds" of books. He got so wired he went for midnight runs to burn off the energy.

His drive may be one of his greatest strengths, but it's also one of his biggest weaknesses. He broadcasts his energy rather than focuses it. His presidency had a thousand initiatives and no central theme. He was wildly undisciplined.

"I am a person motivated and influenced by so many diverse forces I sometimes question the sanity of my existence," he wrote as a high school student.

Dean Keith Simonton, a professor of psychology at the University of California at Davis, and author of a book titled "Greatness," says Clinton is considered by most historians to have been an average president. He notes that one Clinton trait, wanting to be liked, is often associated with poor presidencies, largely because of scandals involving friends and cronies. Warren Harding once said he could handle his enemies, it was his friends who were giving him problems.

In his book "Bob Dole," Richard Ben Cramer describes the way powerful politicians bend the world to their will. "He has to know that he is The One," he writes, referring to the generic presidential aspirant. "He will make war and peace, guide the nation, and change 250 million lives . . . an age of those lives will bear his name forever . . . his name and his face, wife, kids and dog will be known to billions -- across the planet -- they'll look to him, listen to him, depend on him . . . he will bend the story of mankind on Earth." (Ellipses in original.)

Biographer Ron Chernow, author of the best-selling "Alexander Hamilton," sees similarities between his subject and Bill Clinton. Both transcended their origins.

"These are self-invented figures. There is no one in their childhood like them. There is no one who could have served as their models," Chernow said.

He added, "They never really leave behind the darkness of the past. And I think there must be a terrible moment of realization that even though Clinton has become president, that on some level he's still the chubby boy from Hope, Arkansas. Or in the case of Hamilton, that even though he's the treasury secretary, he's still the illegitimate street urchin from St. Croix."

Drive by itself is not enough to make a person rise to power. Shenkman says that every president he has studied has been idealistic. Ronald Reagan was driven by his conviction that communism was evil. Richard Nixon viewed himself as a peacemaker. Lyndon Johnson, says historian Caro, revealed as president his deep compassion for the poor. All presidents have flaws, some deep and tragic, but they would never have ridden into history without some powerful sense that they were the good guys, the heroes.

In that self-revelatory essay in high school, Clinton wrote, "What a boring little word -- I! I, me, my, mine . . . "

But the people who shape the world will always latch onto I, me, my, mine and never let go. In the end they may even write a memoir, and call it something like "My Life."

Greatness in their future: At top, Bill Clinton as band major in 1964 and high school student Lyndon Johnson in 1924; above, Richard Nixon in the early 1930s, Jimmy Carter in 1938 and Ronald Reagan in 1931.Men who grasped the brass ring: Above, Lyndon Johnson said as a teen he would become president; here he takes to the campaign trail for the Senate in 1948; right, Teddy Roosevelt challenged himself physically despite his asthma; below, John Quincy Adams, pushed toward the presidency by familial obligation; below right, an aspiring young Bill Clinton meets President Kennedy in 1963.