Barack Obama last night sought decisively to dispel the lingering fears around his historically-charged presidential run, telling America that the "greatest risk we can take" would be to continue the politics of the past that had kept Democrats out of the White House for eight years.
An exultant crowd of more than 75,000 people packed into a sports stadium, with millions more watching across the world, to witness him accept the Democratic nomination.
"We are better than these last eight years, we are a better country than this," Mr Obama declared, as he predicted November's election would be a defining moment when voters "restore America's promise" by rising up "to insist on new ideas and new leadership, a new politics for a new time".
He strode out on the stage at the mile high Invesco Stadium on the 45th anniversary of the "I Have A Dream"civil rights speech delivered by Martin Luther King, knowing that his bid to be the America's first black president remains a source of both inspiration and suspicion.
"I get it," said Mr Obama, "I realize that I am not the likeliest candidate for this office. I don't fit the typical pedigree, and I haven't spent my career in the halls of Washington.
"But I stand before you tonight because all across America something is stirring."
It was the same spirit, he said, that in 1963 had led Dr King to reject fear and frustration to tell a crowd "of every creed and colour, from every walk of life" that in America, "our destiny is inextricably linked - that together, our dreams can be one".
At the end of a Democratic convention in which his party has put on a carefully-crafted public display of unity, he went out of his way to praise both Hillary Clinton - with whom he had fought an epic battle for the nomination and her husband, Bill,the former president whose White House record has sometimes been slighted by Mr Obama.
The bulk of his speech, however, was devoted to addressing those voters who still think his exotic roots are too different, his politics too elitist or his experience too thin to be president.
He linked his own extraordinary inter-racial and international family background to the direct experience of ordinary Americans struggling with daily lives. In the faces of soldiers returning from Iraq he saw that of his grandfather who had marched with Patton's army, while the students struggling to get through college reminded him of his mother who did the same while bringing up two children on food stamps.
"These are my heroes. Theirs are the stories that shaped me. And it is on their behalf that I intend to win this election and keep our promise alive as President of the United States," he said
While voters have become used to Mr Obama's eloquence, last night they were also shown a glimpse of anger. "Tonight, I say to the American people, to Democrats and Republicans and Independents across this great land enough! This moment - this election - is our chance to keep, in the 21st century, the American promise alive."
Acknowledging that some people regarded his rhetoric about hope and change as mere 'happy talk', Mr Obama gave his primetime audience a detailed tour of his programme. He even dared to be boring as he turned from health, education, energy and foreign policy to a discussion on tax codes.
The chief target of his speech last night was, inevitably, John McCain, with Mr Obama saying the same Republicans responsible for two terms of George Bush and Dick Cheney would, at their convention next week, "ask this country for a third".
Despite Mr McCain's claim to be a maverick, Mr Obama said the Republican nominee had voted to back President Bush ninety percent of the time. "I don't know about you, but I'm not ready to take a ten percent chance on change," added Mr Obama to one of many ovations.
The Illinois Senator denounced attacks on his patriotism by reprising a line he used four years when he first burst on to the national stage with a speech at the last Democratic convention.
"The men and women who serve in our battlefields may be Democrats and Republicans and Independents, but they have fought together and bled together and some died together under the same proud flag," he said.
"They have not served a Red America or a Blue America - they have served the United States of America. So I've got news for you, John McCain. We all put our country first."
But Mr Obama also landed his own low blows, describing Mr McCain - who is 72 today - as subscribing to an "old, discredited Republican philosophy". Later, in criticising his opponent's stubborn refusal to end the Iraq war, he said: "We need a President who can face the threats of the future, not keep grasping at the ideas of the past."
Mr McCain last night put out a cheeky TV advert congratulating Mr Obama on a job "well done." His campaign said it had stopped any leak of their vice-presidential pick", who will be unveiled today, in deference to the Democratic nominee's big moment