Not only is the old conflict alive and well, it's the very engine of politics
The lesson that Sinn Fein will have seen affirmed by this election is that the party thrives when a unionist leader is angry.
Deadlock between the big ideologies of unionism and nationalism is a vote-generator for both sides, so there is little for either to gain by moving beyond the constitutional quarrel.
Sinn Fein insists that it wants equality, respect and integrity for everybody; that it is not a sectional party, but a champion of real democracy.
That's a good line, but republicans know now that they have every incentive to go on presenting unionism as the only problem, an anti-democratic, ethnic monolith that is genetically incapable of according equality to others.
The same lesson was illustrated in the past by the experience of a great stand-off with Ulster Unionist leader David Trimble, when he was the top unionist and the issue between them was IRA decommissioning.
Ostensibly, that appears to be an issue that Sinn Fein lost after years of being worn down by Trimble's insistence.
In fact, in the only sense that any party ever wins, by expanding its electorate, that crisis produced a huge victory for Sinn Fein in the overtaking of the SDLP. It was Trimble who lost out by trying to be the compromiser.
So, the old factionalism still works better than anything else with the nationalist electorate, as with the unionist electorate, too.
After 10 years of unbroken devolution, this old principle is now affirmed beyond doubt. If Sinn Fein is to continue growing then its past experience tells it that it will do so by positioning unionism as an arrogant and unyielding oppressor; as an enemy, not an ally or partner. And, luckily for it, unionism seems eager, at times, to oblige.
This is the most depressing prospect for our politics here: the old conflict is alive and well. Worse, it is the very engine of the whole political machine.
And it heaps such rewards on parties that play by the old sectarian rules that they would be reckless to think of putting it behind them. Unionists who have fallen because they tried to be reconcilers go back to Faulkner and Trimble. Mike Nesbitt last night joined their ranks. But the same logic is true within nationalism. The SDLP is a victim, too.
So, also, is Martin McGuinness, who, though he was much honoured by Sinn Fein speakers in the media yesterday, is viewed within republican circles as having been too nice to the DUP and too compliant; a bit of a walkover.
When the party reframed its political mission away from conciliation towards putting manners on the DUP, support that was draining away surged again.
While the current structures stay in place future leaders of nationalism will know that the best way to revive their fortunes and call people back to them is to lock horns with unionism - not to sidle up to it.
McGuinness had tried to avoid this crisis, but the cynical political judgment will be that that was a bad call.
The decision to confront Arlene Foster delivered more to Sinn Fein than any effort to cut her more slack would have done, not that she ever conceded that she needed, or wanted, any.
The problem at the heart of this is a political structure based on the St Andrews Agreement that incentivises sectarianism. So, the future is inter-communal contention, hopefully contained at the level of inter-party acrimony, with both sides of the quarrel content that they are at least pleasing their voters.
This puts all thought of reconciliation and a shared future behind us, though parties will continue to pretend that that is what they want.
Yet the geography in Stormont has changed in ways that undermine the St Andrews plan to give power to parties rather than communities.
We are approaching the day when the nationalist community will have more MLAs than the unionist, yet the biggest party will be the DUP.
By the St Andrews formula, that entitles the DUP to the First Minister's seat, but in the original Agreement of 1998, it would have ruled that a nationalist would have it.
The case now for total equality between the First Ministers will be irrefutable and there will be no case for retaining the title of Deputy First Minister.
The decline of nationalism, detected after last year's election, has been reversed by the Sinn Fein call to stand up to the DUP, and Sinn Fein is now proportionally stronger than ever in the Assembly. That gives it more clout in the coming talks.
And while Gerry Adams says that he only insists on past agreements being delivered on, his tone and humour suggest a desire to humiliate the DUP and prolong the crisis.
Brexit plays into this for nationalists, too. Part of the reason they are angry with the DUP is that party's support for taking the UK out of the European Union. Nationalists feel that as a betrayal.
Having accepted that there could not be a united Ireland without unionist consent, they feel that the courtesy was not reciprocated when it came to the prospect of constitutional change that nationalists didn't want.
Sinn Fein, the SDLP and the Alliance Party have already been meeting with European governments to urge a special status for Northern Ireland. That is the big battle to come - much bigger than the quarrel over an Irish Language Act.
And Brexit will now be presented as an imperial imposition on the Irish, endorsed by the British puppets the unionists.
And on those terms, judging by this election, Sinn Fein will make an impressive case and win a lot of support for it.