Barack Obama never attended Donald Trump’s wedding and had no history with the man until the rise of birtherism. Now Trump runs for the presidency against Obama’s record, claiming America isn’t great.

So this election is personal. It’s about Obama’s legacy.

And whether there was an explicit deal or a wink and a nod, the President of the United States came to Philadelphia to do for Hillary what Bill Clinton did for him four years before.

He was the right man for the job.

There is no shortage of memorable DNC speeches: Jesse Jackson in 1984 and 1988, Mario Cuomo’s tale of two cities, Ted Kennedy ending his campaign, Obama’s keynote in 2004 and now his speech in Philadelphia; perhaps the greatest of them all.

Obama spoke of his faith in the “generous, bighearted, hopeful country that made” his story possible.

And in a stark contrast to the Republicans, he spoke of his optimism for the future.

He defended his record of 15 million new jobs, an auto industry saved, comprehensive healthcare reform, and justice delivered to Osama bin Laden.

But he emphasized that change is hard.

“This is not your typical election,” said the president. “It’s not just a choice between parties or policies; the usual debates between left and right.  This is a more fundamental choice – about who we are as a people, and whether we stay true to this great American experiment in self-government.”

Obama’s right that, “what we heard in Cleveland last week wasn’t particularly Republican – and it sure wasn’t conservative.”

It was authoritarian and cynical, placing trust and responsibility not in the American people but in a man on horseback.

“And that is not the America I know,” said Obama. “The America I know is full of courage, and optimism, and ingenuity.  The America I know is decent and generous…America is already great.  America is already strong.  And I promise you, our strength, our greatness, does not depend on Donald Trump. In fact, it doesn’t depend on any one person.”

Obama compared Reagan’s “shining city on a hill” with Trump’s “divided crime scene that only he can fix” and reminded the audience that American power comes not from a savior promising law and order.

“We don’t look to be ruled,” he said.

“Our power comes from those immortal declarations first put to paper right here in Philadelphia all those years ago; We hold these truths to be self-evident, that all men are created equal; that together, We, the People, can form a more perfect union,” said the president. “America has never been about what one person says he’ll do for us.  It’s always been about what can be achieved by us, together, through the hard, slow, sometimes frustrating, but ultimately enduring work of self-government.”

His message was to vote and to participate in the arena, rather than looking to an outsider to solve it all.

“If you want to fight climate change, we’ve got to engage not only young people on college campuses, but reach out to the coal miner who’s worried about taking care of his family, the single mom worried about gas prices,” said Obama. “If you want to protect our kids and our cops from gun violence, we’ve got to get the vast majority of Americans, including gun owners, who agree on background checks to be just as vocal and determined as the gun lobby that blocks change through every funeral we hold.  That’s how change will happen.”

Obama spoke of democracy not as a spectator sport but as the politics of “yes we can.”

It’s the antidote to Trump.

America is great, but not perfect. Millions of Americans need help. But the coal miner in West Virginia still has a role to play in his own recovery. It’s the only way it works.

According to Trump, if he’s not elected, the jobs will never come back, and the country is going down. And that’s a dangerous message.

A message Obama dissected, by speaking directly to registered Republicans

In 44 fitting minutes President Obama  captured the politics of personal responsibility and American exceptionalism from the party of Reagan now dead and gone.

But if Hillary Clinton wins, the Democratic Party will be the party of Barack Obama for years to come.

During the 2008 campaign, candidate Obama aspired to being a transformational president, like Reagan, and that’s a legacy he cemented Wednesday night.