Clearly, there is now no question of whether or not Jeremy Corbyn has a mandate to lead the Labour Party.
Twice in the past year, party members have been given a choice -- twice, they have given Mr Corbyn their overwhelming support. Voices both inside and outside the party have set out the likely electoral consequences, and their views have been rejected. Labour's rank and file has shifted decisively to the left, and Mr Corbyn is their clear choice.
This is the business of the 600,000-plus members of Labour's internal electorate. What concerns the rest of us is the impact of their decision. Does it make a Labour government more or less likely? And what will it mean for other parties?
Mr Corbyn's supporters reject the opinion polls and critical consensus that he cannot win, pointing to packed-out rallies and two huge leadership election victories.
They believe he is building a new mass movement, energising a community who stayed at home in past elections, because they didn't feel anyone represented them. If these supporters can be turned into Labour voters, they argue, anything is possible.
Some argue the 2020 election is unwinnable whoever leads Labour. They see a 10-year project, to fundamentally shift the party to the left, so that once voters have tired of the Conservatives, this more revolutionary Labour party is the only viable alternative.
The question is whether these new voters can replace the ones Mr Corbyn and his supporters are undoubtedly scaring away. One-in-three voters who backed Labour in 2015 prefer Theresa May in Downing Street to Labour's leader.
The key to winning back power is taking seats off other parties. For Labour, that means seats across Scotland, where the SNP remains dominant, and in central and southern England. There's little evidence Mr Corbyn's style of politics is winning many new supporters here. New votes in seats you already hold are, to put it bluntly, useless at a general election.
And this doesn't resolve the Labour Party's problem at Westminster, where the overwhelming majority of MPs have publicly opposed Mr Corbyn's leadership, campaigned for a rival candidate, and now find after a miserable summer that nothing has changed.
A formal split still seems unlikely. Mr Corbyn's opponents in the Commons are not about to surrender the Labour Party to him. They feel it has been stolen from them, just like those on Labour's left did during the Blair years.
So what about reconciliation? Could those who so loudly walked out of the Shadow Cabinet slink back in? A few might, and Mr Corbyn has repeatedly offered a warm welcome. But the harsh words of the past few months can't be unsaid, and many may feel it hypocritical to submit to a leadership they decried as disastrous just a few months ago.
There is bad blood on both sides. The party members are baying for blood, not least because they accuse the MPs of gerrymandering, excluding people from the leadership election because they were Corbyn supporters, and setting a higher financial bar to voting in the hope of squeezing out his poorer fans.
Some form of accommodation between Labour's warring sides is essential, not just for the party. A Conservative government with a tiny majority is embarking on Brexit negotiations with the opposition obsessively naval-gazing. Labour needs to stop that, and concentrate on holding ministers to account on this most vital business.
Perhaps acting a bit more like a government in waiting might, just might, begin to turn things around.