The Brexit negotiation process has vindicated pessimists at every turn. Not in well over a year has any meeting between British and EU leaders concluded with both sides as much as hinting at grounds for optimism on the prospects of a negotiated withdrawal for the UK.
With recriminations growing, relationships deteriorating and the October 31st departure date coming ever closer, the chances of averting a catastrophic no-deal exit had, by this week, never looked more remote.
It was striking, then – and encouraging – to hear Leo Varadkar and Boris Johnson emerge from their meeting in Liverpool on Thursday and announce they could see "a pathway towards a possible deal".
That was enough for Michel Barnier, the EU's chief Brexit negotiator, to seek the approval of the EU27 for a new round of negotiations with London, which began straight away.
There is a long way to go before a deal can be done. But there is one last opportunity
The current optimism must be tempered by the fact that the two sides are almost out of time – a deal must be in place by next Thursday, when EU leaders gather for a summit in Brussels – and that, even if a political compromise can be struck, a great deal of technical work must also be carried out.
Several roadblocks could yet impede progress. Dublin and London may see a pathway, but the EU27 will be on guard against any shift that could threaten the integrity of the single market.
And then there is Westminster, where Theresa May’s deal – and, as a result, her premiership – foundered. As an ally of Brexiteer ultras and a newly installed Conservative leader, Johnson is in a stronger position than May was to sell a compromise to his party.
He will make the reasonable case that the Tories would be badly exposed to the threat from the Brexit Party in the upcoming British election if it went to the polls without having delivered on his "do or die" pledge to meet the October 31st deadline. But, if hardline Brexiteers baulk at any attempt to face down the Democratic Unionist Party (DUP), Johnson could conceivably need support from Labour MPs in leave constituencies to get any deal over the line.
Those challenges notwithstanding, both sides – the EU27 and the UK – have strong incentives to reach a deal. The language and tone will be critical. Dublin will feel vindicated if, as expected, it succeeds in pulling Johnson back towards the logic of the backstop he previously repudiated.
But Dublin and Brussels must avoid any triumphalism. The DUP may attract little sympathy, having backed itself so clumsily into its current self-defeating position over the past three years, but it's in the interests of Northern Ireland – and the various relationships formalised under the 1998 Belfast Agreement – that Arlene Foster's party be allowed to extricate itself from the current crisis without being humiliated.
There is a long way to go before a deal can be done. But there is one last opportunity. It must be taken.