In his decision to act, by himself, on immigration, President Obama chose between two sides of his political self.

It’s hard to remember now, but once upon a time, bipartisanship was near the heart of Obama’s political appeal. In the speech that introduced him to Americans, at the 2004 Democratic National Convention, Obama’s most famous line was neither a plea for universal healthcare nor a condemnation of the war in Iraq. It was a call for overcoming America’s political divide: “The pundits like to slice and dice our country into red states and blue states…[But] we are one people, all of us pledging allegiance to the stars and stripes, all of us defending the United States of America.” When Obama ran against Hillary Clinton, a key rationale for his candidacy was that he was not a combatant in the long-running Baby Boomer civil war over the 1960s. He was a liberal who conservatives didn’t hate.

But, from the beginning, this side of Obama’s public persona sat uneasily alongside another. It wasn’t just that he promised both bipartisan reconciliation and progressive change. It’s that Obama understood American history well enough to know that progressive change only arrives through bitter, divisive, even ugly, struggle. When George W. Bush explained America’s moral progress he tended to describe it as frictionless. “The American story,” Bush said in his first inaugural address, is “a story of flawed and fallible people united across the generations by grand and enduring ideals …. Americans are called to enact this promise in our lives and in our laws. And though our nation has sometimes halted and sometimes delayed, we must follow no other course.”

Obama—who spent his student years obsessed with the civil-rights movement and then became a disciple of Saul Alinsky—talks differently. In his second inaugural, he said, “Through blood drawn by lash and blood drawn by sword, we learned that no union founded on the principles of liberty and equality could survive half-slave and half-free.” Then he name checked “Seneca Falls, and Selma, and Stonewall,” places where powerful and privileged Americans ridiculed, arrested, beat, and killed other Americans for demanding equal rights.

The part of Barack Obama that knows how change really happens in America has long been quietly at war with the part that wanted to stay on good terms with Republicans, and with powerful elites in the business and financial worlds. In the most consequential decision of his first term, when he decided to pass healthcare reform via reconciliation, Obama chose identity No. 1 over identity No. 2. Now, in what may prove the most consequential decision of his second term, he has done the same. He has decided once again to trigger the hatred of defenders of the status quo because, I suspect, he knows American history well enough to know that real moral progress doesn’t happen any other way.

Would another Democrat have done the same thing? Perhaps. But at moments like this, it’s worth remembering what a strange political creature Obama is. Many politicians grow up hero-worshipping other politicians. Democrats come of age idealizing Franklin Roosevelt or John F. Kennedy. Republicans grow up idealizing Ronald Reagan. Not Obama. In his youth, he wasn’t an aspiring politician. He was an aspiring activist. And it wasn’t politicians who inspired him.

On the second page of The Audacity of Hope, Obama writes that he entered politics to lay claim to “a tradition that stretched from the days of the country’s founding to the glory of the civil rights movement.” On the book’s second-to-last page, he talks about running late at night up the steps of the Lincoln Memorial and “imagining the crowd stilled by Dr. King’s mighty cadence.”

The King that inspired Obama was not the sanitized, Disneyfied figure whom everyone now claims. In his youthful passion for the civil-rights movement, Obama discovered the real King—the man whom the FBI tried to blackmail, the man who risked his relationship with the Johnson administration to condemn Vietnam, the man who spent his final days alongside striking garbage workers. It was that King, and that civil-rights movement, which gripped Obama as a young man, and which he tried to recreate in his own age.

Yes, Obama is a pragmatist. Yes, he is professorial. Yes, he wants to be liked by his ideological opponents and by the powers that be. But he also knows that were he in his twenties today—a young man of color with a foreign parent and a foreign-sounding name—he might be among those activists challenging the vicious injustice of America’s immigration system. When Obama talked about “the courage of students who, except for the circumstances of their birth, are as American as Malia or Sasha; students who bravely come out as undocumented in hopes they could make a difference in a country they love,” he wasn’t only comparing them to his daughters. He was comparing them to himself.

For progressives, this was always the real promise of Barack Obama. It was the promise that a black man with a Muslim name who had worked in Chicago’s ghettos—a man who had tasted what it means to a stranger in America—would bring that memory with him when he entered the White House. It’s a promise he fulfilled on Thursday night.