John Key's achievement on Saturday is historically remarkable. Only two post-war Prime Ministers, Sir Sidney Holland in 1951 and David Lange in 1987, have increased their party's share of the vote while in power. Mr Key matched their achievement at the 2011 election. This time he has increased National's share for a third time. That has not happened since 1925 when Sir Gordon Coates led the Reform Government to victory after the death of William Massey.
To find a precedent for the same leader increasing his party's seats at three successive elections we have to go all the way back to Richard Seddon in 1899.
That is the scale of the achievement. It is one that allows National to contemplate not just another three years in office but quite possibly a fourth term. That, however, depends on what happens now. The Prime Minister has made it clear he wants to continue with the partnerships he formed six years ago, though pending the count of special votes National might be able to govern alone.
With Act - whose failure to win party votes consigns it to remaining a National appendage - National is assured of enough seats to do what it likes. The first thing it might want to do with that power is to amend the Resource Management Act so that economic considerations can be given equal weight with the environment. The Maori Party and Peter Dunne were able to prevent this in the previous Parliament. Now National will not need their votes.
But if Mr Key maintains his previous character, he will not legislate in a subject as important as this without seeking broader support than he strictly needs.
Opposition parties are not always wrong, especially when they reflect a concern as deep as that of environmentalists on this issue. Likewise, he might take another look at issues that arose during the election campaign, such as internet surveillance by intelligence agencies and the whole question of child poverty.
A thorough, dispassionate review of subjects such as these, removed from the heat of an election, would set a good tone for the third term. Governments at this point of their tenure can too easily succumb to arrogance at the very time the public begins to tire of them and look for change. The Labour Party will be looking to capitalise on that possibility over the next three years.
But first Labour has some work to do. Even if its new rules did not require a review of its leadership the Labour caucus would need to do so. David Cunliffe campaigned as strongly as could be expected against a tide that was still running for National, but the country has not warmed to him and his tactical judgment at times in the campaign was not good.
Mr Cunliffe's mid-campaign decision to rule the Maori Party out of a post-election deal was cited by Te Ururoa Flavell yesterday as a factor in his probable response to an invitation from Mr Key.
Labour's diminished caucus will struggle to lead the opposition alongside Winston Peters and the Greens. Mr Peters spurned conciliatory comments from National yesterday, while the Greens counted themselves lucky to hold 10 per cent of the vote. Both could be more effective if they were prepared to work with Mr Key but for different reasons they have chosen another three years in the wilderness.
The Prime Minister has received a ringing endorsement from an electorate that did not take kindly to efforts to smear him. Economic and business confidence will be strengthened by the result.
If Mr Key can use these conditions to lead the economy to a higher plane of growth, his third electoral triumph will not be his last.