AT 11pm tonight English nationalists and their friends here will finally get their way when Britain formally leaves the European Union.
Historic is an overused word but this is a historic moment.
Nothing will change overnight but the ultimate consequences are likely to be profound for all in these islands.
We are in uncharted waters and all that we can be certain of is that we will not hear the last of Brexit for a long time.
The imminent negotiations between the UK and the EU on a trade deal and the outworking of the Irish Protocol will see to that.
In 2016, a month after the Brexit referendum, I wrote in this space: "Sometimes in the tide of history an event takes place that has unintended consequences, a game-changer with ramifications that are cross-cutting and multi-layered: societal, economic, constitutional... Brexit has the hallmarks of such an event."
Nothing that has happened in the tumultuous years since suggest that my assessment was overblown.
We have seen inter alia demands for another independence referendum in Scotland that surely cannot be indefinitely resisted, public discourse about the prospects for Irish reunification that would have seemed unthinkable not long ago and the humiliation of the DUP by an untrustworthy British Tory prime minister.
No-one really knows what the madness of Brexit, imposed on us here against our consent, will lead to.
The future is deeply uncertain from several perspectives, including the constitutional and the economic, but it most certainly is not without hope, as our politicians led jointly by Arlene Foster and Michelle O'Neill in apparent resolve to make a go of it, get back to work at Stormont.
And hope was that Divine gift that sustained the late and great Seamus Mallon in the darkest of days, and inspired him to toil for a brighter future, as those of us in that remarkably eclectic congregation in Mullaghbrack were reminded by Archbishop Eamon Martin in his beautifully crafted homily at the patriot's funeral.
And reminded of also in the TV archive clips broadcast in the aftermath of his death.
I took a note of his words.
"If we have the courage and the desire for two communities to live together in a palatable way, if we want that, we can get it. It is going to be tough. It is going to require a lot of goodwill and hope. If we haven't got hope we have nothing," we heard Mr Mallon say on BBC Newsline.
It was as if he was pleading from the other side of eternity to all of us to don the helmet of hope and commit in good faith and in a spirit of generosity and goodwill to make the Good Friday Agreement truly work, however belatedly.
It's early days but the new power-sharing executive - composed of MLAs chastened by the message on the door steps last month - has made a promising start.
Whether it has been, for example, Diane Dodds at economy, Conor Murphy at finance, Robin Swann at health or Nichola Mallon at infrastructure, they have struck a mature tone and displayed a business-like approach.
The Executive's priority above everything else must be to set an example for the rest of us in building trust, working collectively for the common good, avoiding self-indulgent 'solo runs', concentrating on common goals such as tackling the crisis in the health service and in schools, and using their influence in mitigating - in so far as they can - the impact of a border in the Irish Sea.
The unionist and nationalist parties around that Executive table may have diametrically opposed constitutional aspirations but they should put those to one side and focus on what they have in common for the rest of this mandate.
They have quite enough to be getting on with without obsessing about the Union or a united Ireland. That would be a fitting ongoing memorial to Seamus Mallon.
