The voting on Friday was so peaceful that the young Garda standing outside the polling station in Crumlin, Dublin, had nothing to do. When a small gang of little boys gathered around him, he seemed glad of the company. They asked to see his handcuffs and he took them out. Soon, he had two delighted youngsters cuffed together. As an old lady passed on the way in to vote, he asked her "Will I release them, Ma'am?" "Ah do," she replied, "they're innocent."
As an image of what was happening on Friday, this vignette could hardly have been more eloquent. The vote was really an exercise in slipping off the handcuffs and releasing the next generation from the categories in which their predecessors have been confined. It provided, not a clear map of the future, but the freedom to move into the present-day reality of what it means to be Irish.
One of the cliches about the Irish is that we live in the past. Like all cliches, it is partly true, especially of traditional unionism. But it is just as true that the defining affliction of Irish nationalists has been a tendency to live in the future. It is no accident that the IRA's slogan - Tiocfaidh a ar la - is in the future tense. The present has been judged by how near or far it is to the glorious day when Ireland will become a single, pure, uncomplicated political entity. Real living people have been treated as expendable stepping stones towards the great day that is to come.
Even for non-violent nationalism, "Ireland" has been something that did not really exist in the here-and-now. "When I talk about my Ireland," Charles Haughey told us a decade ago, "I am talking about something that is not yet a complete reality. It is a dream that has not yet been fulfilled." Unionists, of course, have had their own version of the dream future. At its starkest, in the religious vision of many born-again Protestants, it is the Day of Judgment, when the Lord will return to earth, separating the saved from the damned. In a milder, more secular version, it is a final defeat of age-old enemies, the routing of Catholic resistance, and the restoration, once and for all, of a Protestant domain.
Those dreams of the future have too often made a nightmare of the present. On Friday, the people of the island decided to wake up.
The Belfast Agreement was constructed in order to defuse these dangerous visions of the future. It asked every sort of Irish person to embrace the complex, ambiguous present-day reality of the island. It proposed the radical notion that we could live quite happily without knowing where, in the long run, we were going. It asked us to replace fixed visions of the future with the pleasures of contingency, to accept the truth of ordinary human experience in which everything is in some sense temporary.
At its heart is a profound shift in the Irish sense of belonging. Both unionism and nationalism have always seen themselves as claims over territory. Their rhetoric has been full of land and landscape. The historian Oliver McDonagh astutely noted in his book States of Mind that "In one sense, the Irish problem has persisted because of the power of geographical images over men's minds."
The Belfast Agreement seeks to replace geography with demographics, to make people rather than territory the touchstone of political identity. And it recognises that people don't have the fixed, primeval stability that land does. They are a complex, contrary, infinitely variable amalgam of hopes and fears, aspirations and desperations. They move and shift and change their minds. They die, and others take their place.
By placing people at the core of political identity, the agreement replaces the words "will" and "must" with the words "may" and "might". Northern Ireland is now a place that is arguably unique - a place that nobody claims and nobody owns, a place that is free to become whatever its people can agree that they want it to be. At the same time, the Republic of Ireland has placed its own future in doubt, defining itself as a place that may or may not exist a century from now.
The JOY of the agreement is that uncertainty has become a source of liberation rather than one of fear. We don't know whether and in what form Northern Ireland will continue to exist. We don't know how much effect the rapid and profound series of changes that is under way in the Republic will alter the attitudes of unionists.
We don't know how much the absence of violence will itself alter the sectarian landscape. We don't know how far the reshaping of Britain implicit in the establishment of Scottish and Welsh parliaments will go, or how it will interact with other changes in the allegiance of Northern Protestants.
And what the agreement essentially says about these unknowns is "So what?" It reminds us that there is no future in trying to predetermine the outcome of change. It suggests that it is far more important to know what will not happen than to know what will. And it guarantees that what will not happen is coercion, bullying, stampeding, the negation or obliteration of anyone's basic rights.
The Ireland inaugurated on Friday is perhaps the most self-conscious example of Benedict Anderson's definition of a nation as an "imagined community". It recognises that what people are is what they think they are. By endorsing the agreement, the people of both parts of Ireland wrote into the basic laws of two states the radical idea that a nation exists in the rich, changing perspective of the mind. The calm dignity with which that mind was stated on Friday suggests that the mind is not, after all, such a bad place to live.