Forced at the point of a gun to give up every visual snapshot but one from the early hours of yesterday, the keeper, I think, would be Jesse Jackson. The Reverend stood there in a Chicago park, oddly anonymous among that biblical host, struck dumb by the wonderment, his eyes blankly unfocused as the tears streamed forth. The angry black man, whose struggles helped pave the path to the White House for the serene black man he waited to greet as his President-elect, was angry no more.
Hurriedly, I tried to explain to the 11-year-old rubbing his sleepy eyes between us in bed why his mother and I were moved to tears of our own by the sight of Jackson, by reference to the things I imagined flashing through his mind – the original sin of slavery, as enshrined in the Constitution; Jim Crow and Rosa Parks, Selma and Montgomery, the Kings Martin Luther and Rodney. Humanity's perspective on itself doesn't change every day, and when it does the compelling instinct is to share it with our young, ensuring the memory is branded on their minds indelibly.
Almost four decades ago, my father woke me before dawn to watch those jerky pictures of Neil Armstrong walking on the Moon. I remember the texture of that moment (the chill, all the fiddling with the old black and white's aerial) as clearly as a grainy vision that not long before had seemed no less outlandish a fantasy than the election of a black president seemed two years ago.
Our son will never forget what he saw and heard yesterday, and if he cannot yet fully comprehend the magnitude, or if his transparent joy was vicarious on his parents' behalf, well, there are worse reasons for a day off school.
For all its enormity, however, the aura of epochal inevitability that already enshrouds this election wants careful handling. We always retroactively impose a coherent narrative structure on moments of global immensity, as if their grandeur eviscerates all credible alternative outcomes; as if to dwell on the role played by chance is to diminish their magnificence.
But there was nothing inevitable about this one at all. Had just one of the myriad "what ifs?" been answered differently, Obama would not be heading for Pennsylvania Avenue.
What if he'd become a US senator two years earlier than he did? He might have voted, reluctantly, to sanction the invasion of Iraq, and denied himself the thrusters that powered his insurgent candidacy. What if Hillary had campaigned seriously in Iowa, or had a post-Super Tuesday Plan B to prevent his delegate-gathering clear run through February? The glory would probably have been hers yesterday. What if Obama had played safe, and not given his majestic speech on race in Philadelphia in March? Another angry black minister, Jeremiah Wright, would have ended his prospects.
Had John McCain avoided celebrating the strong fundamentals of the economy when he did, left Sarah Palin to her moose, or campaigned as the McCain of 2000 – the funny, endearing self-deprecator of last weekend's Saturday Night Live; the noble spirit who gave such a gracious valedictory in Phoenix – six Obama voters in a hundred might have switched sides and handed the old man the White House. So there feels something properly miraculous about the sequence of long shots and half-chances that coalesced to produce this result.
No sooner was that result in, though, than Obama revealed how he means to govern in a wonderfully sombre, untriumphalist speech of acceptance. Barely breaking into a smile until he greeted Michelle and his girls at the end, through tone and words he told us that he will be a teacher-president, seeking to educate rather than browbeat about the phalanx of challenges that face America and the wider world.
He will be at once a pragmatic centrist and a velvet revolutionary, steering Congress towards bipartisan agreement while striving to alter the language, tenor and reality of national and international politics beyond recognition. And he will remain the community organiser he was on Chicago's South Side and as a candidate, harnessing the raw power of informed idealism to guide America towards an era less riven by material greed, blinkered vision, cultural warfare and racial mistrust.
Change has come to America, as he said it would, and if the change his victory represents is purely symbolic, that symbolism is the sine qua non of more concrete change. The 15-year-old Arab who on 20 January sees the skinny black guy with the funny Muslim name give his inauguration speech on Al-Jazeera will be less pliable to those peddling him poison about the Great Satan. For that amorphous mass of deranged spite we call al-Qa'ida, yesterday surely marked the end of the beginning, while for those here and elsewhere who cleave still to Enoch Powell's pernicious ravings, the phantasmal tide of the blood-soaked Tiber surely ebbed a little too.
At last America has reminded us why we fell for her schmaltzy idealism long ago, and why for all the malevolent lunacy of recent years she remains the world's best and only hope, by doing what remains unimaginable in any other predominantly white major democracy.
Even if the popular vote margin would have been tripled for a white candidate of such rhetorical and campaigning genius, more than half of voters realised Dr King's dream, and judged a man not by the colour of his skin but by the content of his character.
That bit was difficult enough, but the rest is more so. The road Obama is taking is long and winding, with landmines almost every step of the way, and soon enough his more fervent adorers will accuse him of betrayal when they realise that the instant creation of earthly paradise is beyond even his powers. There are no guarantees that he will find the solutions to the economic, diplomatic, military, educative, social and climatic problems that form the most hideous welcoming committee ever to greet an incoming president. But Jesse Jackson, although doubtless prone to flaring up from time to time, will never be so angry again.
The faces of every hue surrounding Jackson in Chicago were enraptured where he was stunned, beatific where he was bamboozled. If I judged it right, the look in their eyes spoke not merely of transcendent relief and joy, but of people inspired and elevated by the yearning to be better than themselves.
If nurturing that ambition is the core of Obama's mission, as I believe – in the finest and least dogmatic sense of it, this is as profoundly Christian a political leader as we have seen – it's understatement ad absurdum to say he'll have his work cut out. Be it the Moon landing, the release of Nelson Mandela, the dismantling of the Berlin Wall or Obama's election as 44th president of the United States, moments when unbridled hope unites the planet and infuse us with a sense of shared identity are flimsy and tragically brief.
But we know them when we meet them, they taste indescribably delicious, and we never forget their savour for as long as we live.