Most convention speeches are forgotten almost before they’re finished. But tonight in Philadelphia, Michelle Obama delivered a speech that will be replayed, quoted, and anthologized for years. It was as pure a piece of political oratory as this campaign has offered, and instantly entered the pantheon of great convention speeches.

Obama stepped out onto a stage in front of a divided party, including delegates who had booed almost every mention of the presumptive nominee. And she delivered a speech that united the hall, bringing it to its feet.

She did it, moreover, her own way—forming a striking contrast with the night’s other speakers. She did it without shouting at the crowd. Without overtly slamming Republicans. Without turning explicitly negative. Her speech was laden with sharp barbs, but she delivered them calmly, sometimes wryly, biting her lower lip, hitting her cadence. It was a masterful performance.

She offered an upbeat vision of how far America had come, and—like her husband 12 years before—put herself forward as living evidence of what American ideals might accomplish. “That is the story of this country,” she said.

The story that has brought me to this stage tonight. The story of generations of people who felt the lash of bondage, the shame of servitude, the sting of segregation, but who kept on striving and hoping and doing what needed to be done so that today, I wake up every morning in a house that was built by slaves. And I watch my daughters, two beautiful, intelligent, black young women, playing with their dogs on the White House lawn. And because of Hillary Clinton, my daughters and all our sons and daughters now take for granted that a woman can be president of the United States.

When Obama first said that she wakes up every morning in a house built by slaves in a commencement address a month ago, right-wing commentators were quick to attack her as unpatriotic. Instead of backing away from the sentiment, though, she expanded on it. She explained it. She offered it as evidence of American possibility.

And then a First Lady often attacked for lacking patriotism, a woman accused of not loving her country, turned the table on her critics:

So look. So, don't let anyone ever tell you that this country isn't great—that somehow we need to make it great again—because this right now is the greatest country on earth. And as my daughters prepare to set out into the world, I want a leader who is worthy of that truth.

It was an attempt to frame the terms of the 2016 election. Nearly two-thirds of Hispanics, more than four in five African Americans, believe that America’s best days lie ahead. Michelle Obama didn’t shy away from the worst of what her country has done, but she insisted that it is improving, that it is already great, and that it can be greater still.

Few politicians have lost by betting on the optimism of the American people.