Northern Irish nationalism is unmistakably on the move, making dramatic advances politically, socially, economically and numerically. Even a preliminary bout of number-crunching in the wake of this month's national and local elections shows that something big is happening.
Those numbers, and much else, are changing fast; and since Northern Ireland's history and politics are based on the numbers game, its very fabric is being transformed. The ratio of two-thirds Protestant to one-third Catholic which was the consistent backdrop to politics for so many decades has gone, to be replaced by a new mathematical and political model.
And not only are there more nationalists than ever before; they are more confident, younger, and better off than ever. They have, in John Hume and Gerry Adams, formidable political leaders with a flair for publicity and, abroad, a talent for winning friends and influencing people which is the envy of their Unionist opponents.
Unionists will find a great deal to worry about in last week's local election results, which show up both falling numbers and falling morale. They will worry in particular about Sinn Fein, whose popularity is soaring at a rate never before seen in Northern Ireland politics.
Catholics have increased from a third to at least 43 per cent of the population, and probably more. The political effect of this, masked for many years because much of the Catholic population was under voting age, is now impacting on politics.
In 1983 nationalists held two of the 17 Westminster seats; today five of the 18 MPs are nationalist. In the general election the nationalist share of the vote touched 40 per cent for the first time ever. In the 1985 local government elections Sinn Fein and the SDLP together won 189,000 votes; in last week's elections they polled 237,000.
The Unionists lost control of four councils, the western territories of Cookstown, Fermanagh, Strabane and, carrying a huge symbolic charge, Belfast itself. Before last week 16 of the 26 councils were controlled by Unionists, six by nationalists, while four had no overall majority. Now Unionists control only 13, nationalists have eight, and five have no clear majority. Citadels are crumbling.
The fall of Fermanagh, the western-most and one of the geographically largest councils, means none of the west is under Unionist control. Overall there is still a clear Protestant majority but increasingly it is concentrated in the east, particularly in the greater Belfast area.
The Ulster Unionists and Sinn Fein, with 13 councillors each, are the largest parties in the city, which now resembles a political doughnut, with an ever-more nationalist core surrounded by Protestant satellite towns. Both middle-class and working-class Protestants are resorting to a local version of white flight, moving out to leave the city to the Catholics. This phenomenon, mischievously described by a nationalist councillor as Orange flight, may well be accelerated by the fall of city hall.
This exodus is one of the ways in which Unionists are responding to the new demographic realities. Another section of the Protestant electorate simply switched off, and stayed at home on polling day. "There's apathy and confusion among the Unionist people," one defeated Belfast councillor complained. "They've nobody to blame but themselves, because they didn't come out to vote."
One key question is how the traditional Unionist parties will react to the shifts in population and hence in power. The septuagenarian Rev Ian Paisley, who has just had two bad elections in a row, is too old a dog to learn new tricks. His deputy, Peter Robinson, may some day do business, but not until his Ayatollah departs the scene. In the meantime Mr Paisley, having spent three decades in the last ditch, is not about to leave it now.
The focus of attention is therefore on David Trimble and his Ulster Unionists, who are still the largest party. If Mr Paisley will not do a deal - either with Sinn Fein or without it - then in logic the Ulster Unionists are the only remaining candidates. The party's performance has been mixed, with a poor forum election last year, then a good Westminster result, but the local government outcome was cheerless for them. The theory goes that Mr Trimble, now that he has reached an election-free zone, will have more room to manoeuvre.
It is not a particularly comfortable position for him, for the Paisleyite fundamentalists have not gone away. But on the other hand Tony Blair and Mo Mowlam - the woman who put the Mo into momentum - will be pushing hard for him to show new flexibility and early movement.
The changing demographics and other elements argue for a historic new deal, which means a historic new compromise, but Mr Trimble will be well aware that previous Unionist leaders who struck out in that direction quickly perished. One set of voices within Unionism argues - quietly, for the charge of heresy is still a potent accusation - that it is time to make a deal, on the grounds that the demographic and other factors mean Unionism's position weakens with each passing year.
A key defining moment will come, perhaps quite soon, if and when the IRA declares a second ceasefire. If they do, it will be because of a government assurance of speedy entry into round-table talks, and Mr Paisley has made it clear that if republicans walk through the front door he will storm out through the nearest exit. At that point the Ulster Unionists must decide whether to go with him, or stay and negotiate.
While a Paisley walk-out would exert a powerful pull, Mr Trimble could receive a fair amount of cloud cover, should he decide to stay, from the fringe loyalists. Several of their members are still slightly hung over from celebrating their conspicuous electoral success.
These groups, the Progressive Unionists and Ulster Democratic Party, are known as the public voice of the illegal loyalist paramilitary groups, but after winning a number of council seats they can now claim to have their own mandate. While their associates have guns and bombs, most of those who voted for them did so because the PUP and UDP project a willingness to compromise.
Their securing an appreciable foothold in electoral politics is a serious nuisance for the established Unionist parties, since it means the Protestant vote is fragmented. But the loyalists will probably stay in talks if Sinn Fein come in, and London and Dublin hope that would encourage Mr Trimble to stay, too.
Just as thousands of Protestants believe the loyalists when they say they want to be less paramilitary and more political, so do most nationalists accept that Sinn Fein wants a new peace process. As one seasoned observer put it: "The nationalist community has accepted that Sinn Fein and the IRA want to pack it in, move away from the violence and get some sort of overall settlement. The nationalist community believes them."
This may well be the principal explanation for the extraordinary rise in Sinn Fein's vote, which leapt from 12.4 per cent four years ago to 16.9 per cent last week. The fact is that nearly all of the fast-growing nationalist vote is going to Sinn Fein, while support for the SDLP remains static. In the Eighties Sinn Fein built a solid but limited electoral base of around 11 per cent of the vote, but since the early Nineties, when republicans adopted the language of peace and later staged a 17-month ceasefire, this has skyrocketed to almost 17 per cent.
There are other explanations too. If the allegations are correct and republicans have indeed been stealing votes, this clearly augmented their total, though hardly by more than a few thousand of their 107,000-vote total.
But whether or not Sinn Fein has been stealing SDLP votes, they have certainly been stealing the SDLP's clothes in terms of policies, concepts and language. Phrases such as peace, peace process, the need for the two governments to work together, and so on, all originated with the SDLP and have been appropriated by the republicans. "The Sinners have been copying Hume's eckers [homework]," complained an SDLP teacher.
Sinn Fein has also been reaping the rich harvest of new nationalist voters, in particular those who were jolted into voting for the first time by last year's Drumcree disturbances. The sense of nationalist indignation at that episode has scarcely dimmed since last July. They are also mobilising a younger and more dedicated - if only because more likely to be unemployed - constituency.
It is impossible to say which of these ingredients has contributed most to the new republican voting surge, though it is likely the peace aspect has provided the greatest boost. But the bad news for Unionists is that there are more nationalists than ever and they are more ambitious and energetic than ever.
This new assertiveness, coupled with the relative decline of the Protestant population, is the key to explaining why so many controversies arise over loyalist marches. In most cases the problems arise when loyalists attempt to continue to parade through districts which were Protestant but are now Catholic. First, the districts have changed their religion; second, their denizens no longer accept without demur what are viewed as triumphalist exercises.
The day when nationalists may have a majority is still far off. But the rise in the Catholic population, taken together with this new nationalist confidence and a lack of Unionist direction, means that the whole system is changing.
Nationalists in general, and the republican movement in particular, have clearly become empowered politically: the hope is that this will lead the IRA to conclude that a real and ready-made alternative to violence exists. The chances of a new ceasefire have been strengthened by the new sense that nationalism is on the move, and that a new political landscape is fast taking shape.