There will be plenty of time to chart Barack Obama's attempt to navigate a course between the exigencies of the old politics and the promise of the new, between yesterday and tomorrow, youth and experience, black and white. For now, take a moment to consider the mind-bending improbability of what just happened.

A young, black first-term senator — a man whose father was from Kenya, whose mother was from Kansas and whose name sounds as if it might have come from the roster of Guantanamo detainees — has won a marathon of primaries and caucuses to become the presidential nominee of the Democratic Party. To reach this point, he had to do more than outduel the party's most powerful and resourceful political machine. He also had to defy, and ultimately defeat, 389 years of history.

It was in 1619 that the first Africans were brought in chains to these shores, landing in Jamestown, Va. Ever since — through the War of Independence, the abolitionist movement, the Civil War, Reconstruction, Jim Crow, the great migration to Northern cities and the civil rights struggle — race has been one of the great themes running through our nation's history.

I'm old enough to remember when Americans with skin the color of mine and Obama's had to fight — and die — for the right to participate as equals in the life of the nation we helped build. Watching Obama give his speech Tuesday night marking the end of the primary season and the beginning of the general election campaign, I thought back to a time when brave men and women, both black and white, put their lives on the line to ensure that African-Americans even had the right to vote, let alone run for office — a time when Democrats in my home state of South Carolina were Dixiecrats, and when the notion that the Democratic Party would someday nominate a black man for president was utterly unimaginable.

Tiresome, isn't it? All this recounting of unpleasant history, I mean. Wouldn't it be great if we could all just move on? Bear with me, though, because this is how we get to the point where, as Obama's young supporters like to chant, "race doesn't matter." No one will be happier than I will be when we reach that promised land, and we've come so far that at times we can see it, just over the next hill. But we aren't there yet.

Yet the amazing thing isn't that there were instances of overt, old-style racism during this campaign, it's that there were so few. The amazing thing is that so many Americans have been willing to accept — or, indeed, reject — Obama based on his qualifications and his ideas, not on his race. I'll never forget visiting Iowa last December and witnessing all-white crowds file into high-school gymnasiums to take the measure of a black man — and, ultimately, decide that he was someone who expressed their hopes and dreams.

When historians and political scientists write books about this extraordinary campaign season, surely they will seek to assess what impact Obama's race had on his prospects. But they will also devote volumes to exploring how he put together a fundraising apparatus that generated undreamed amounts of cash, and to how his organization drew so many new voters into the process, and to how his young supporters made use of social-networking Web sites such as Facebook and MySpace, and to how his delegate-counting team managed to consistently outthink and outhustle everyone else. It will be written that Obama's nomination victory owes as much to adroit management as it does to stirring inspiration.

Will Americans take the final step and elect Obama as president? Should they? Is this first-term senator up to the job?

We'll find out soon enough. At the moment, to tell the truth, I don't care. Whether Obama wins or loses, history has been made this year. Maybe there's more to come, maybe not; but already — after 389 long years — it's safe to say that this nation will never be the same.

Eugene Robinson is part of The Washington Post Writers Group. Reach him at eugenerobinson@washpost.com.