Washington - George W. Bush happened to be in the right place at the right time.
He deeply resented the suggestion that the White House was his for the taking - a bird's nest on the ground, as they say in Texas. But with his family's name and fundraising machine, and a shrewd strategist, Karl Rove, playing kingmaker, it practically was.
Bush added a powerful personal gift: his likability. What he didn't have was a track record on the national scene. When he became president, he'd spent just six years as an elected official, a public resume about as thin as, well, Barack Obama's. But experience, especially in world affairs, didn't seem to matter much at the start of the 21st century, a time of unusual peace and prosperity.
Undaunted by his narrow victory in the disputed 2000 election, the new president seized power boldly. He pledged to bring civility to a bitterly divided capital, expand democracy around the world, and use the government's big budget surplus to shore up the retirement of his fellow baby boomers. Though his popularity was already slipping, he rammed a huge tax cut through Congress and made common cause with Democratic icon Edward Kennedy on a bipartisan plan to leave no schoolchild behind. Then, as the saying went, Sept. 11 changed everything.
Bush leaves office as one of the least popular presidents of the modern era. By his own admission, he failed to meet some basic goals.
"The tone in Washington got worse, not better," he told ABC's Charlie Gibson. America's global standing plummeted. Staking his political capital on overhauling Social Security was a mistake, he said. He and Rove worked to build a permanent Republican majority; instead, their party is in the worst shape since Watergate.
Bush clearly hopes for a Truman-like vindication from future historians. They have their work cut out for them. Indelible images of Bush's Iraq policy - scenes of American brutality at Abu Ghraib prison and an Arab journalist flinging shoes at the U.S. president - reflect the aftermath of an invasion that, at the time, was called by some the biggest foreign policy blunder in American history.
Bush countered that it might take decades to see the wisdom of his policy, but the cost has already been high, in blood and treasure. As the war winds down, a clear majority of Americans say the U.S. military effort in Iraq is going very well, according to a new Pew Research Center opinion survey. But most Americans still believe it was a mistake to send troops there in the first place.
The intriguing question is whether Bush privately agrees. He told ABC he had been "unprepared for war" and called the pre-war U.S. intelligence failure in Iraq "the biggest regret" of his presidency.
In his next breath, he appeared to come closer than ever to admitting that there might not have been a war at all, had he known that Saddam Hussein didn't have weapons of mass destruction.
"You know, that's an interesting question," he said. "It's hard for me to speculate."
Whether or not Bush's presidency was among the worst of the modern era, as many historians have said, it was bookended by two events of enormous consequence: the 2001 terrorist strike and the recession that began at the end of 2007, which may be the worst since the Great Depression
The 9/11 attacks by Islamist extremists have come to be regarded by many as the defining event of the Bush years. They also produced the high point of his career - Bush's "war on terror" speech to Congress, which helped reassure and unify a shaken nation.
There have been overlooked successes, such as expanded U.S. efforts to combat HIV/AIDS and malaria in Africa, but also the botched government response to Hurricane Katrina.
He presided over one of the most expensive new federal programs ever - a prescription drug benefit for seniors - but left it to a successor to fix the Medicare program's unsustainable cost. And an economic downturn that began in his final year in office is getting worse.
That raises an unexpected question: Will Bush's legacy be as a "wartime president," as he likes to call himself, or the Herbert Hoover of the 21st century, as a reporter asked in one of his many exit interviews?
President Obama will inherit plenty of unfinished business from Bush. The situation in Afghanistan is deteriorating. Iran is closer to building a nuclear bomb. There's war in Gaza and, looming over everything else, a worsening, and worrying, economy that continues to sputter worldwide.
Obama, a cool customer, says his advisers will turn their "intellectual firepower" on these problems. His high-powered, Ivy-educated team is being compared to President John F. Kennedy's "best and brightest," also an unsubtle reminder that brainpower is no substitute for sound judgment and experience.
Because Obama is such a ubiquitous celebrity, it's easy to forget how swiftly he's risen. He arrived in Washington only four years ago and found an opening for a presidential run that, by his own admission, he didn't expect to see so soon.
Now it's his turn to govern.