From a former Mother Jones editor who lives in Chicago and is writing a book about South Africa.

So, here was one of the striking things about being in Grant Park, in the midst of hundreds of thousands of people, as it was announced that Barack Obama will be the new president -- the current of disbelief that one experienced even as it happened.

From the black woman behind me who wept and cheered and wept again to the older white man in front of me who’d voted for Republicans all his life until this election, each announcement of a state won by Obama was followed by a brief hush before the cheers.

It reminded me of so many conversations I had with South Africans last year. At the beginning of many interviews about the dynamics of post-transition politics in South Africa, the tables would turn and the person I’d arranged to question would cross-examine me about whether it was even marginally conceivable that this highly unlikely candidate could prevail.

I thought he could, but only because I’d seen, close-up, how his Quixote-like run for the U.S. Senate had unfolded in 2004 from audacious upstart to oddball triumph.

The persistence of the doubt, though, fed for me on disappointments that stretched back 40 years, to my activism as a teenager in another presidential campaign I’d made calls for, gone door-to-door with, and volunteered in -- the race of Robert F. Kennedy, Jr. in 1968. He was shot to death the night after I’d seen him address a crowd that looked as diverse and as hungry for change as the crowd that gathered in Chicago last night.

Perhaps this turning point in U.S. history, among other things, marks an end to the sort of apocalyptic thinking that understandably rolled out from the end of the 1960s (Medgar Evers, JFK, Malcolm X, Martin Luther King, Jr., and RFK -- all assassinated). It could only have been led by a post-Baby Boomer, and I think it has profound implications for post-post-modern politics.

In 1988, during his primary run for president, Jesse Jackson told me, “Maybe it’s my job to bang on the door so one day someone else can walk through it.”

Maybe now we actually get a chance to take up the real-deal gritty details of genuine social change because the easy, cynical excuses -- that, for example, my effort doesn’t matter, OF COURSE a mixed-race man can't be elected to the presidency, or the rug will be pulled out from under us at the last minute anyway (as it was in 2000), so why make the effort? -- have been stripped away. It’s potentially liberating, but of course the rest depends on us.

In itself, this seems a profound step -- the end of apocalyptic thinking -- that probably has utility both in this old, creaky, hidebound democracy here and in the newer, more dynamic and currently-troubled democracy there.

On Tuesday night, I was surrounded by people who’d worked their hearts out for a victory that, at the moment of its announcement, still seemed nearly impossible to believe. To his credit, president-elect Obama didn’t take long after exulting in the victory to spell out how much there is, now, to be done.