You can just picture it – the bleak, dreary midwinter day when Theresa May tables her deal to the House of Commons.
It contains provisions for a more distant economic and political relationship than she might have liked in an attempt to win over her eurosceptic flank – and most controversially of all, giving Northern Ireland a special status, sharing a customs zone with both the EU and the UK , effectively drawing a customs border down the Irish Sea.
She loses the DUP in the process but hopes to gain dozens of her own MPs who would approve that the dreaded backstop had been ditched and that Great Britain could conduct her own trade deals, unsullied.
But it goes down to a stinging defeat. Boris Johnson, among others, decry it as the PM acquiescing to "an EU attempt to carve up our country".
Naturally, this isn't quite what happened. Theresa May's deal was different to Boris Johnson's, the one essentially described above.
But the truth is, had Theresa May produced Boris Johnson's deal, word for word, that scenario would have played out, it would still have been soundly rejected in parliament.
It would almost certainly have been rejected by Mr. Johnson himself and many in the arch-eurosceptic European Research Group (ERG).
We know this because when such provisions in Northern Ireland were mooted at the time, they lambasted them. It would have been rejected too by the DUP, who, perhaps to reject their credit today – they are consistent, if nothing else.
So what has changed? Part of this is simply time, the passage of which is a commodity of underrated importance in politics.
Many MPs are weary – weary of an entire year of parliamentary attrition, the torrent of abuse from constituents, the existential angst that has come to suffuse British politics, a suffusion to which the House of Commons and its members are ill-accustomed.
Some now scream for closure, where once they were willing to defer in the hope of getting more. The same phenomenon has taken place through many political crises.
What seems sacrilege in one moment, becomes wisdom if not the gospel after just a little time.
With the Irish crisis, a problem which divided British politics in the late 19th and early 20th centuries (and one which has returned to haunt it now), the idea of partition of Ireland would have been completely unacceptable to many in 1910.
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By 1922, Westminster just wanted the problem to go away and be acceded to the once unthinkable.
With Brexit the phenomenon is the same, but the pace of modern politics being as it is, the process place in quadruple time.
But this is about something deeper: the Tory hardliners are coming onboard because their side has finally won.
The fight against Mrs. May's deal was as much about her as about its contents.
Her opponents voted against it repeatedly because they wished to remove her and wagered that that was the best way.
That is why as soon as Mrs. May said she would go, in exchange for votes for her proposals, many key players, including Boris Johnson and Jacob Rees-Mogg almost instantly converted to voting for what she offered, despite only days previously describing it as "vassalage".
Her failure was their success and they knew it.
The climax of Mrs. May's premiership was thus just another battle in the endless Conservative party civil war – a war which though caught and centered in the boggy marshlands of Brexit, extends far beyond it: a battle about what British conservatism is and what it should be .
But there is now a clear victory in that battle.
The Brexiteers and, to be frank, the right of the Conservative Party, have secured control at last. They have the leader they want. A leader they like – not one they have merely tolerated.
Many of them have ascended to positions of influence, power and prestige.
It doesn't get any better for them, they have nothing to gain from continued failure. And moreover, nor do the ground troops.
There is no longer any Brexiteer king over the water, some Leave in tooth and claw figure who might secure a harder Brexit for those most fervently attached to it. Boris Johnson is for them, the best they are going to get.
Their victory is so complete, that there is even total asymmetry of warfare: the remaining Tory moderates, those like Theresa May who were expelled from power, or like Nicholas Soames who were expelled from the party, traiped into the lobbies with those who vanquished them , showing a loyalty to Mr. Johnson which he and his best supporters never reciprocated.
But it isn't just a tale of skulduggery. It is true that Mr. Johnson has changed the basis of political calculations for many Brexiteers.
I have thought much in the last 24 hours of something an ardent Leaver said to me in one of the tortured interims between Mrs. May's meaningful votes.
They told me: "Frankly, I'll only believe this is the best we can get when one of our own has been out there and had a go."
That has now happened.
Alongside this, the Conservative eurosceptics' complete victory in the long Tory civil war, this explains why, suddenly, a deal which is not so different to what came before, is so viable when the other is so limp.
Only Nixon could go to China, perhaps only Boris Johnson could go to Brussels.
Watch a special edition of Kay Burley @ Breakfast from 8am on Sky News, with continuing coverage from Westminster throughout the day.