Unionism has been shaken to the core by the Assembly election results.
It should not have been so shocked, because nationalism has barely advanced at all over the last decade.
In the Stormont election of almost exactly a decade ago, March 7 2007, the combined nationalist vote was 41.8% of votes cast on a 62.3% turnout of the Northern Ireland electorate.
In this election, the combined Sinn Fein-SDLP vote was 39.8% of the vote.
Even if People Before Profit is added to that total on the grounds that its support came overwhelmingly from nationalist areas (although it did not designate as nationalist) and could return to nationalism (as to some degree it did in West Belfast), the total potential nationalist vote seems to be 41.6%.
The turnout in this election was 64.8% in this election, which if anything makes it a slightly more accurate representation of the feeling in the country than 2007 was.
During that decade, the Catholic population and the number of voters who are Catholic has edged upwards, as it has done slowly but relentlessly over the decades.
Therefore, the results can in fact been seen as a sign that the Union is in healthy shape when it comes to Northern Ireland (Scotland is another matter).
So why has political unionism with a capital U been rocked to the core?
Three main reasons.
• First, Sinn Fein are on the brink of being the biggest party. The nationalist vote has barely moved in 10 years but Sinn Fein’s vote has edged up since 2007 by 1.7% (from 26.2% to 27.9%) and the DUP vote has edged down by 2.0% (from 30.1% to 28.1%). This means that two are a mere 1,170 votes apart.
• Second, the seat differential between nationalism and unionism is extraordinarily close now (40 seats to 39) and reflects the vote share in a way that it did not previously do. Formerly, unionists were notably ahead in terms of percentage vote share (6% ahead in 2007) but further ahead still in seat differential (11 seats ahead of nationalists in 2007). This is mainly to do with lower levels of vote transfer within unionism this time (more on that below).
• Third, unionism was lulled into a false sense of security in 2011 and 2016, as the nationalist vote fell and unionism pulled comfortably ahead. It seemed that nationalism was perhaps withering on the vine.
Arlene Foster has come in for relentless criticism since the results emerged last week. One thing does seem clear – that last year she allowed herself to be enticed into the notion that her party’s position was secure for five years, This was understandable given the scale of the victory but it led her often to cite her mandate, which ended up antagonising some Ulster Unionist MLAs, let alone anyone else.
But even if the DUP had been safe for five years, as anyone who is over the age of 35 will know only too well, five years goes by in a flash.
The only thing that matters to anyone who is interested in Northern Ireland’s place within the UK is the long term trend.
In terms of Orange and Green, that has changed little over the last decade.
But something very significant is happening nonetheless.
An ever growing centre ground is emerging that will permanently hold the balance of power at Stormont, and that will decide the shape of this Province.
The combined Alliance-Green-others vote on March 2 was around 100,000.
The combined unionist-nationalist vote was 701,000 (367,000 unionist, 334,000 nationalist).
At first sight this means that tribal parties seem to thrash the centre ground by a hopelessly large margin of seven to one.
But if you add the SDLP and Ulster Unionists to the centre ground, the figures get much closer. The total then is about 500,000 to firmly Orange-Green parties and 300,000 to the centre.
This suggests that Mike Nesbitt was ultimately on to something in his comment about transferring to the SDLP, even though his delivery and timing came as too much of a surprise.
There are reports across Northern Ireland of SDLP to transferring to UUP, UUP transferring to SDLP but also SDLP and UUP voters transferring to a range of candidates other than Sinn Fein and the DUP.
This in fact is to be expected.
Consider the Ulster Unionist Party, for example: it got 30% of the vote in the 1982 Assembly election.
If back then a small minority of those UUP voters, say 20% of them, transferred to Alliance before the DUP, then such UUP 1-Alliance 2 voters would have been 6% of the overall vote.
Now that the total Ulster Unionist vote is only 13% of the overall vote, you would expect those most liberal of the old Ulster Unionist voters to be the least likely to have departed for the DUP in recent years.
And thus it is logical that a higher percentage of current UUP voters are transferring to Alliance than UUP voters of 10 or 20 or more years ago.
Likewise that a higher percentage of remaining SDLP voters are transferring to parties other than a Sinn Fein that they always rejected and to which they have not been tempted to defect.
Such trends towards an enlarged centre greatly complicate the prospect of a single unionist party,logical though in many respects it is now that there is so little between the DUP and UUP.
The concept of NI21 was also a logical one even if the personalities were such that it did not work in practice.
Such a unionist party that is clearly pro-Union but also emphatically against tribal politics would probably emerge if ever there was a single unionist one.
Mr Nesbitt’s difficulty was that at times he pushed the UUP towards being such a party and at others towards unity.
• Ben Lowry (@Ben Lowry2) is News Letter deputy editor