Brexit is both the cause of the Tory leadership contest - it was too much for Theresa May - and is the toxin that threatens to destroy the contest to replace her and her party.
The reason is that even if the new prime minister were to take the UK out of the EU - which can by no means be taken for granted - there is unlikely to be a Brexit dividend for him or her or the Conservative Party.
Because for most Tories or their potential supporters, Brexit is no more and no less than the duty that voters set the government in that 2016 referendum.
So far the defining characteristic of this government is its failure to fulfill that duty. If it ever were to actually do what it was instructed to do, gratitude from voters is less likely to be its reward than a mumbled “you took your time”.
As Sajid Javid the home secretary pointed out yesterday, Winston Churchill’s prize for winning the Second World War was to be sent to the backbenches: the British thanked him for his service but were more excited by Labour’s plans to build a land fit for heroes.
So the candidates face an impossible challenge: as an absolute minimum they have to inspire confidence they can deliver Brexit, because - as Jeremy Hunt says - the Tories will be annihilated if they flunk that.
But they cannot be confident of winning the next election unless they have a few ideas to fix what’s wrong with the UK - especially when most of the flaws (a housing crisis, work that doesn’t properly reward and stagnating incomes for millions, jobs being destroyed by robots, care for the elderly melting down, air that is poisoning us, a UK whose constituent countries are pulling apart, a political culture being poisoned by hate, to name just a few) have little or nothing to do with membership of the EU.
Here is the Tories’ tragedy: the appalling challenge of inspiring confidence that Brexit can be done is crowding out all other important thinking - just as it wrecked Theresa May’s hopes of building a non-Brexit legacy.
What have been the magnificent policies for a new age unveiled so far? Gove’s plan to replace VAT, one of the few relatively simple and effective taxes (all things are relative); Johnson’s suggested tax cut for English people on higher earnings funded in part by Scottish taxpayers; Hunt’s proposal to slash corporation tax, Raab’s to do the same to the basic rate of income tax.
There may be a case for any or all of these traditional Tory remedies. They do not represent bold new thinking for an economy and society undergoing radical transformation.
Most of the candidates are playing continuity politics in an era of profound discontinuity. Only one candidate - in style if not necessarily yet in substance - seems to intuitively grasp how much has changed.
Rory Stewart is reassuringly bonkers. There is evidence in the wider country he is being heard. But his MP colleagues and Tory members may be so much in their Brexit bunker that they will fail to notice.