In terms of electoral success, Jacinda Ardern still has rivals in her party, but only in the ghosts of Michael Joseph Savage and Peter Fraser.
In the Greens' history books, there are no rivals to Marama Davidson's and James Shaw's triumph last night.
Yes, the Greens have previously won a higher percentage of the vote, reaching 11.1 and 10.7 per cent in 2011 and 2014 respectively.
But those numbers were secured against the backdrop of Labour's failed campaigns under Phil Goff and David Cunliffe. Last night's achievement occurred in an entirely different context.
Under MMP, no small party which has formally supported a government has managed to break the 5 per cent threshold at the next election.
Davidson and Shaw not only smashed that apparent rule, but the Greens' party vote has increased from 6.3 per cent in 2017 to 7.6 per cent, and could go a smidgen higher with overseas votes.
Shaw deserves a huge part of the credit for holding the party together in 2017 after the debacle following Metiria Turei's welfare speech and for the multi-party agreement on the Zero Carbon Act. His abject self-criticism after the Green School scandal underlined his reputation for integrity and that his party adamantly opposes private education.
But any party that has even a second member becomes a coalition of some sort. Very inexactly, Labour is a coalition of South Auckland office cleaners, middle-class teachers and Grey Lynn pseudo-intellectuals, and National one of conservative provincialists and more liberal urban business owners. Whenever these coalitions are out of balance, Labour and National face catastrophe.
The Green coalition similarly spans a spectrum from Audi e-tron drivers in Remuera to actual communists in Aro Valley.
That is, it contains people who genuinely believe carbon trading is just more neoliberal subjugation, that the New Zealand state should be overthrown and that the prisons should be emptied.
Davidson leads this part of the Green alliance but is sufficiently respectful of Shaw and his faction that the coalition has held together. Even Shaw's welcome public denunciation of the antisemitic and terrorist-aligned boycott, divestment and sanctions movement against Israel was reluctantly tolerated.
(There are lessons in all this for parties which didn't do so well on Saturday, but these can be saved for another column.)
With this weekend's triumph, the Greens must decide how formally to tie themselves to the Ardern juggernaut. Ardern and her innermost circle of Grant Robertson, Chris Hipkins and Megan Woods will of course have the major say, but the three main options are a coalition agreement, a confidence and supply arrangement or to sit on the crossbenches and deal with issues as they arise.
To the extent the polls ever justified thinking about it, Act had broadly decided to go for the third option had they and National had the numbers. That is, Judith Collins would have been told she could be prime minister and appoint a cabinet, but there would be no advance guarantees on anything else, including even the Budget. The larger party would need to negotiate everything and anything it wanted to do. The smaller one could also preen that it had rejected all the baubles, perks and salaries of office.
This is undoubtedly the best strategy for small parties to maximise their own power, albeit to the point of irresponsibility. But it only works if the small party is actually needed by the larger one.
In this case, Labour has a clear working majority all on its own. Ardern may choose to work with the Greens for her own benefit but she need not listen to them – or even speak to them – on anything at all. In practical terms, the Greens – and also the Māori Party – have no more leverage over Labour than National or Act. Outside the Government, they are no more than a taxpayer-funded pressure group with the use of Parliament's platform. That may be enough for the radical side of the Green coalition but its other supporters want outcomes.
For wiser heads, the Greens have no real choice but to opt for a more formal agreement with Labour, assuming Ardern offers one. To have any real power at all, they need to be ministers who operationally control departments and budgets, and attend Cabinet committee meetings as equals with their Labour rivals.
The radicals will rightly point out this also involves existential political risk. When push comes to shove, the Greens will still have no real power over Labour, but their ministers will be bound by Cabinet collective responsibility, obliged to publicly support decisions they don't agree with. Green ministers will be in danger of doing little more than applying a Green stamp to Labour's agenda, to the extent it turns out to have one.
There are no good options here. But if the Greens get the decision wrong, in last night's triumph may well lie the seeds of a disaster in 2023.
Matthew Hooton is an Auckland-based PR consultant, whose clients have included the National and Act parties. These views are his own.