So before plunging back into the grey media river of ifs and buts and the reverses and disappointments to come, it is worth standing back and simply enjoying the event. All political systems need days like these. I heard the news with a shudder of excitement in a Highland Hotel. People were asking each other about the news and smiling. In churches around the country this weekend people will be celebrating and praying - "Let's hope". And in pubs, cafes and millions of kitchens there will be a murmuring of "Well, you never know", and "Hmm. Could be."
This uncommon mood which steals out at some election results, or whether Mandela is released, or at the first IRA ceasefire or a Camp David handshake, cannot be defined or measured. But it is the vital spirit of democracy: if there isn't some hope of making the world better through representative politics, then the system itself begins to rot away.
You could tell the politicians themselves felt some of this - felt, in Tony Blair's phrase "The hand of history". The fact that it was the pursed familiar faces of Ulster hardman who were expressing hope and openness made the breakthrough particularly poignant. To hear Sinn Fein's Mitchell McLaughlin herald "A beautiful day" or David Irvine of the PUP pinching himself and trilling, "I never thought in my life time I would see it", was superbly surreal but undeniably moving too.
The over night political melodrama of this final phase of negotiation was evidently essential to the deal. Without the ticking clock set off by senator George Mitchell's deadline- yet another Northern Ireland time bomb, but one that could only be defused by about a thousand fingers working simultaneously - there wouldn't have been the agreement. I suspect that in those final exhausted hours a few closed minds were prized open, or at least open enough.
It was a heavy, dark, tobacco and coffee-stained seam of mental shrugging, phase-rubbing and deal cutting which will be mined for posh memoirs and pub anecdotes for years ahead - the moment when Clinton reached John Hume in the refreshment pen; the moment so-and-so burst into tears; the bad joke that broke the worst atmosphere ... But this drama, was, only the culmination of a much longer process, composed of ten thousand minute acts of moral courage on the part of a bewilderingly diverse number of people, many of them anonymous and some of them very unpleasant indeed.
One well known man who should be particularly remembered this morning is John Major who seized an IRA offer and began this initiative, to much ridicule at Westminster. He didn't have a big majority, he was leading a unionist party. In many years, his position could hardly have been weaker. Major and Paddy Mayhew would not, I think, have been able to bring things to this point had the Tories, by some magic, won the last election. By the end of that administration the pressure on it was showing and the Northern Ireland peace process needed the fresh authority and energy of Tony Blair's victory to bring it alive again. It needed the big Westminster majority and the knowledge that the new British administration wasn't going away but would be in power for years to come. But without Major and his doggedness and in the mid-1990s, there would have been nothing for New Labour to pick up.
Like John Major, Tony Blair has been heavily involved in his first few days in office. His arrival at Hillsborough this week wasn't a PR stunt by a grandstanding leader flying in to take the credit. These talks nearly failed and this was a final fling by a man who may have inherited them but who has become imbedded in the detail and almost obsessive about it.
The other mainstream politician who emerges with huge credit is of course Mo Mowlam. It was Blair's gamble that her startlingly direct and unconventional style would help rather than smash up the talks. She has put up with some poisonous attacks in the past few months and taken some heart-stopping risk, notably in meeting terrorist prisoners at the Maze. But she has proved herself a genuinely gritty, major-league politician whose plain speaking isn't quirky or merely affected but a different way of doing deadly serious politics. After this week she surely joins the top division in Cabinet and is certainly now the most important female politician in the country.
Bertie Ahern and David Andrews have done exceptionally well, keeping the faith; but they will inevitably be standing in the shadow of John Hume, a good man vindicated, and Gerry Adams, a less good man who is visibly changing. We may not like Adams but then we are not required to like any of these characters; and what we can say is that the Sinn Fein leader, fully aware of the historic fate of Republicans who compromised too early has nevertheless compromised at last. He has remained impressively, if eerily, calm under constant provocation. And there's no doubt a bit more of that to come.
It is however David Trimble who is the most intriguing of the compromisers. Hopes and fears for real peace are embodied in this man, an enormously complicated and combustible mixture of orange, tribal chieftain and modern European social democrat. The distance between Ian Paisley and him is the distance between despair and hope, between a bigot who could never deal and a modern politician who can - and in a way, between the 17th Century and our own. Trimble has shown exceptional courage too in handling a divided party, boiling with would-be replacements. Some of this behaviour in the last few days made one despair but in the end he did the right thing, and as the likely leader of a future Northern Ireland assembly he will be tested and challenged constantly in the years ahead.
The referendum and the elections offer plenty of scope now for the wreckers. There will be splinterings and denunciations and no doubt killings to come as the cave dwellers come out for a final bloody dance of protest. But here is where the rest of the country, politicians, journalists and voters, can also play a part. We must not fall into the easy reaction of questioning the whole process every time a bomb explodes or an inoffensive drinker is murdered in a back street bar.
It would be childish to expect a clean or uncomplicated move from low intensity war to genuine peace. Now, none of us can afford to be cynics and none of us can afford to be children. There will be trouble ahead. But there will be less trouble then there would have been before these past extraordinary days. As of this weekend, all of us in the UK are living in a slightly different country than the one we had grown used to. A better one? Well, obviously.