Just months after he was politically left for dead, Biden told America to get back on its feet.
"The current president has cloaked America in darkness for far too long. Too much anger, too much fear, too much division," the former vice president said. "We can and will overcome this season of darkness."
Biden excoriated President Donald Trump and vowed that while he was accepting his party's nomination for president, he would work just as hard for those who didn't support him.
But his message was more hopeful than ominous. Drawing on his faith in American potential and his own experience overcoming tragedy, Biden said the country was ready to meet its challenges and do great things.
"While I'll be a Democratic candidate, I'll be an American president," Biden said. "I will draw on the best of us, not the worst. I will be an ally of the light, not the darkness."
Biden spoke live to a nearly empty darkened room near his home in Wilmington, Delaware. Supporters in cars filled a parking lot to watch on large screens. Protesters supporting Trump were also on hand. Fireworks burst overhead after he concluded.
Biden said the country faces four crises simultaneously: the coronavirus pandemic, the ensuing recession, renewed demands for racial justice, and climate change. And he said that while Trump has failed in every one of them, the country is up to the challenges.
"Our current president has failed in his most basic duty to the nation — he's failed to protect us," Biden said. "And my fellow Americans, that is unforgivable."
If Trump is re-elected, Biden warned, more people will die from COVID-19, more businesses will shutter and more working people will struggle, even if the wealthiest 1 percent get another tax break.
"He'll wake up every day believing the job is all about him, not about you," Biden said.
But Biden said that doesn't mean hope is lost, even as so many have lost loved ones and livelihoods to the virus.
"Look, I understand it's hard to have hope right now," he said. "I know how it feels to lose someone you love. I know that deep black hole that opens up in your chest, that you feel your whole being is sucked into it. I know how mean and cruel and unfair life can be sometimes.
"But I've learned two things," he continued. "First, your loved ones may have left this Earth, but they never leave your heart. They will always be with you. And second, I found the best way through pain and loss and grief is to find purpose.
"And we have a great purpose as a nation: To open the doors of opportunity to all Americans. To save our democracy. To be a light to the world once again," he said.
The final night of the program also featured video appearances from Biden's family, including his son Hunter, who has struggled with addiction and is rarely seen in public. There was a moving tribute to his other son, Beau, who died of a brain tumor in 2015. And there was a video of his granddaughters attesting to his love of ice cream sometimes hidden from their grandmother.
Democrats also paid tribute to John Lewis, the civil rights leader and member of Congress who died last month, with Atlanta Mayor Keisha Lance Bottoms urging Americans to rise to his example.
"Congressman Lewis would not be silenced. And neither can we," she said. "We cannot wait for some other time, some other place, some other heroes. We must be the heroes of our generation."
Biden, paraphrasing Lewis, said America is ready to "lay down the heavy burden of hate" and end systemic racism.
"America's history tells us that it has been in our darkest moments that we've made our greatest progress, that we've found the light. And in this dark moment, I believe we are poised to make great progress again, that we can find the light once more," he said.
And in the struggle for racial justice, Biden highlighted his vice presidential nominee, Sen. Kamala Harris of California.
"Her story is the American story," he said. "She knows about all the obstacles thrown in the way of so many in our country. Women, Black women, Black Americans, South Asian Americans, immigrants, the left-out and left-behind."
The nomination has been a long time coming for Biden, 77.
After a David-and-Goliath campaign against a powerful Republican in 1972, Biden entered the Senate as both its youngest member and one of its most tragic figures. His wife and their baby daughter were killed in a car accident just weeks after his election, and he almost decided to quit before he was even sworn in.
His story and style made the young Biden a natural potential candidate for higher office, and he first seriously considered a White House bid in 1980. "I remember thinking: I have no business making a run for president," he wrote in his memoir, "Promises to Keep." "I was 37 years old. ... Am I flying too close to the sun?"
Biden decided not to run that year, nor in 1984 despite having taken another serious look at it. And when he finally did jump in in 1988, it ended in humiliation when he withdrew from the race after getting caught having lifted some lines of his speeches from a British politician.
Cowed, Biden focused on his work in the Senate and didn't take another shot at the White House until 2008. But he flamed out early in Iowa, where he finished with less than 1 percent, although he finished with a nice consolation prize — the vice presidency.
He explored another run in 2016 but opted to step aside for Hillary Clinton, citing the recent death of Beau. His 2020 bid got off to a poor start, and many Democrats, including some close to Biden, privately predicted that he would end his career with another embarrassing loss.
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He finished fourth in Iowa, fifth in New Hampshire and second in Nevada before, in the course of a stunning few days, everything turned around. He rallied to a commanding victory in South Carolina and then surged as the other moderate candidates dropped out to endorse him.
"Are we ready? I believe we are," Biden said Thursday night. "This is the United States of America. And there has never been anything we've been unable to accomplish when we've done it together.
"This is our moment. This is our mission," he added. "History will be able to say the end of this chapter of American darkness began tonight. This is a battle we will win."