PHILADELPHIA—I spoke to my mom on Tuesday morning. We talked about Michelle Obama. I was on the floor when the first lady gave her speech and could feel the pride and enthusiasm in the room. She electrified, and viewers everywhere felt it. My mom was one of them. And as we talked about Obama’s speech, she returned to one particular passage from the first lady:

That is the story of this country, 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.

With this paragraph, Obama took the themes of her husband’s speech on the 50th anniversary of the march from Selma to Montgomery, his explication of a progressive patriotism, and distilled them to their essence, tying them to her life and her experiences. Hers, like Barack Obama’s, is a patriotism that acknowledges the pain and injustice of the past but keeps faith with the proposition that Americans will overcome and push forward to a “more perfect union.”

But there’s more here than a restatement of earlier ideas and narratives. It’s no small thing for the first lady of the United States to speak to an audience of millions and tell them, without hesitation, that the White House—the nation’s house, an icon of American liberty—was built and staffed by people robbed of their labor, their freedom, and their dignity. Obama’s choice to emphasize slavery—and, in turn, racism—was a daring one of a piece with the rhetorical legacy of the Obamas’ tenure in that house.

Past presidents have mentioned and discussed slavery. In his 1965 commencement speech to Howard University, Lyndon Johnson delivered a still-remarkable treatise on racial inequality that began with this still-bracing line. “There is a second cause,” to black disadvantage, said Johnson. “Much more difficult to explain, more deeply grounded, more desperate in its force. It is the devastating heritage of long years of slavery; and a century of oppression, hatred, and injustice.”

These are exceptions. Overwhelmingly, when telling the story of America, our presidents lean on the idea of a voluntary society—a nation of frontiersmen and immigrants who came willingly to these shores to find freedom and opportunity. Throughout their time as president and first lady, Barack and Michelle Obama have taken a different approach. Their America is a nation of immigrants. Their America is the melting pot of civic cliché, sure, but it’s also a place of people who didn’t have a choice, who were brought here as chattel and forced to work under the lash, but who kept their belief in better days and salvation. In their hands, this isn’t just an American story; it’s the American story, testifying to the virtues of struggle, faith, and perseverance.

This is what Obama brought with her speech. In a country that often sees its black citizens as dysfunctional embarrassments, it was brave rhetoric. In a country that pathologizes the body Michelle Obama inhabits—that of a dark-skinned black woman—as antithetical to American femininity and womanhood, it was nothing short of radical. Her speech wasn’t offering up the story of one black woman as a story of America; it suggested that America’s story was a black woman’s story as much as anyone else’s.

Quietly, almost matter-of-factly, this was the theme of Monday’s DNC from the moment Baltimore Mayor Stephanie Rawlings-Blake picked up her gavel. The Democrats are now a party of black women. There was Rawlings-Blake, and there was Rep. Marcia Fudge, admonishing the Berners to be respectful of her, and that’s to say nothing of interim chair Donna Brazile and convention CEO Leah Daughtry. Tuesday will feature the mothers of Eric Garner, Trayvon Martin, Dontré Hamilton, Jordan Davis, Michael Brown, Hadiya Pendleton, and Sandra Bland.

None of this came up in my conversation with my mom. She raved about Obama’s line—about a house built by slaves, occupied by a black family—and then I had to go to work. As much as Michelle Obama was speaking to the nation—to Democrats and Republicans, liberals and conservatives—she was also representing millions of black women, speaking to their patriotism, addressing them as citizens of equal worth, affirming their values.

There’s no doubt that this speech was political, first and foremost. Obama will be on the trail, stumping for Hillary Clinton, working to mobilize those black women and bring them to the polls with a version of what she said on Monday night. But it was a powerful piece of performance and symbolism. A reminder—perhaps a final one—that America looks like her. That America is her and all the women who have shared deeply in her experience.

Read more Slate coverage of the 2016 campaign.