Standing on the West Front of the Capitol as the first African-American ever sworn in as president, Obama celebrated that historic achievement, noting that "a man whose father less than 60 years ago might not have been served at a local restaurant can now stand before you to take a most sacred oath."
In moments of crisis, "America has carried on not simply because of the skill or vision of those in high office, but because we the people have remained faithful to the ideals of our forbears and true to our founding documents," Obama said.
"So it has been. So it must be with this generation of Americans."
Evoking the names and values of the Founding Fathers is commonplace in presidential speeches, but in Obama's case the device seemed intended to make a larger point:
The change he hopes to bring about will require even his supporters to accept things they don't want to accept, work with opponents they've long demonized and break long-ingrained lifestyles.
Americans as a whole must adopt a new, more self-denying way of life with little room for "those who prefer leisure over work, or seek only the pleasures of riches and fame," he said. "What is required of us now is a new era of responsibility."
In a passage that echoed Franklin Roosevelt's first inaugural, Obama said, "Our workers are no less productive than when this crisis began. Our minds are no less inventive, our goods and services no less needed than they were last week or last month or last year. Our capacity remains undiminished.
"But our time of standing pat, of protecting narrow interests and putting off unpleasant decisions — that time has surely passed. Starting today, we must pick ourselves up, dust ourselves off and begin again the work of remaking America."
If the speech was exceptionally somber and included relatively few lines designed to draw roars of approval from the enormous crowd, the day nonetheless resounded with jubilation.
More than 1 million people flocked to the National Mall to take part in the event, spilling outward from the gleaming white Capitol steps toward the Washington Monument and the Lincoln Memorial more than a mile away.
Choirs sang. The world's finest musicians — including classical violinist Itzhak Perlman and Yo-Yo Ma, the cellist, along with soul singer Aretha Franklin — performed. High school bands paraded. And tears streamed down faces, weathered and smooth alike, here and around the globe, as the son of a white American and a black African immigrant ascended to his place in history.
The only shadow on the day was cast during the luncheon for the new president in the Capitol's Statuary Hall hosted by House and Senate leaders: Sen. Edward Kennedy (D-Mass.) suffered a seizure and was taken to a hospital. When Kennedy was stricken, Obama hurried to his side, later recalling that Kennedy had been in the Senate for the passage of the Voting Rights Act in 1965.
Kennedy suffers from brain cancer, but an aide said he was awake, talking with family members and feeling well.
Sen. Robert Byrd (D-W.Va.), the oldest member of the Senate, was sitting near Kennedy and became visibly upset. He was taken from the lunch but an aide said later he is fine.
As is traditional, President George W. Bush and Laura Bush were whisked away by helicopter immediately after the inaugural ceremony and headed for their home state of Texas after a private farewell to staff at nearby Andrews Air Force Base.
And almost at once, the wheels of the new administration began to turn.
In the afternoon, new White House Chief of Staff Rahm Emanuel, as expected, put a hold on all regulations the Bush administration had been drafting, pending a review by the new team. Obama is expected to begin issuing his own administrative measures this week.