The most significant thing about the Irish Times opinion poll last week, which showed Fine Gael has opened an 11-point lead over Fianna Fail, is that such a dramatic shift in public sentiment could occur at all.
t indicates that, contrary to the popular view, national mood can and probably will shift decisively one way or the other come the next election.
And Leo Varadkar is now best poised to take advantage.
After the resignation of Frances Fitzgerald, I said that I did not expect to see any movement in public opinion in relation to that controversy.
In other words, if the events in relation to Brexit had not occurred last week it is likely that the poll, taken at the height of those events, would not have registered any meaningful movement in party political support.
That is not to say that the public has not taken note of the latest developments in the Maurice McCabe affair, and the outcome of the related brinkmanship between Leo Varadkar and Micheal Martin which threatened an election.
What the Frances Fitzgerald controversy did tell us, however, was that the public is finely attuned to Brexit and its potential implications for Ireland.
Hence the backlash against Fine Gael and Fianna Fail the weekend before last to the effect that an election was not required and for them to get on with it, with last week's critical Brexit event looming.
Varadkar's handling of the Frances Fitzgerald issue left a lot to be desired, but the young Taoiseach has also kept a close eye on Brexit, and his handling of that has been, shall we say, determined.
First and foremost, his approach has been one of protecting national economic interests against Brexit in a hard form as advocated until last week by the UK government and, it follows, the Democratic Unionists in Northern Ireland.
This brought him into sharp conflict with Theresa May's government, in particular, and, it follows, with the DUP. Undoubtedly that conflict let loose a certain nationalist fervour among the electorate here: bash the Brits.
But that fervour was no more threatening, I would suggest, than will be the case when England is participating in the World Cup in Russia next year and Ireland en masse can be expected to cheer for its opponents.
The fervour also somewhat accounts for such a dramatic rise in Fine Gael's opinion poll support over Fianna Fail.
More than that, however, Fine Gael's support rise is underpinned by Varadkar's successful defence, so far, of the country's economic interests. So right now he has the initiative, and with considerable momentum to boot.
In many ways, the young Taoiseach's job is done, in relation to Brexit, although, the Government must remain vigilant. Nothing is agreed until everything is agreed.
Ireland was used by the European Union, though, to flush out the UK position somewhat, which has been exposed to be as threadbare as most experts have always felt it to be.
Several years of negotiations now lie ahead to put in place what is shaping up to be the most complicated free trade agreement negotiated worldwide, but at this point Brexit looks likely to be soft.
For the first year of those negotiations, Ireland will be represented by Leo Varadkar as Taoiseach and Simon Coveney as Minister for Foreign Affairs. This will present Varadkar with a gilt-edged opportunity to play the role of international statesman, a position into which he is growing quite comfortably.
In some quarters, there was a tendency to dismiss the significance of the opinion poll last week. Those who sought to downplay it noted that it was taken at the height of the dramatic events last week and, therefore, measured a transient mood.
However, possession is nine-tenths of the law and Varadkar possesses the Office of An Taoiseach.
Between now and towards the end of 'confidence and supply', he can be expected to bolster his image as a suitable Taoiseach willing to stand up to those who threaten the national interest.
And as can be read into the opinion poll, there is significant political capital to be mined in that space.
That is not to say that there are not potential downsides ahead for Varadkar.
If it is appropriate to liken the nationalist fervour last week to England in the World Cup, then what lies ahead is more akin to a British & Irish Lions tour. Ireland and the UK's interests will be more closely aligned going forward than they were looking back.
The joint report of the UK and EU negotiators last Friday was fudge, by necessity. But I still can not see Brexit going any way now, other than towards a soft landing.
Increasingly, it looks as though the UK will continue to be moved to a position where, eventually, it will be asked: "What was the point of Brexit?"
The possibility remains that politics in the UK will upend a soft outcome, but that is to assume that hard Brexiteers will take ownership of the Conservative Party, an assumption that should not be taken as read.
It is more likely that, ultimately, there will be a Conservative split, such is the Tory tendency to commit kamikaze politics in recent times.
Beyond that again, Ireland will be exposed in Europe to be without a natural ally, as the UK was our closest friend.
So Varadkar and Coveney, or whoever should be in power, will find Ireland's influence in the EU to be diminished in the medium term or at least until new alliances are forged and developed. More than any other factor, this will eventually become the greatest threat to the national interest.
As to the DUP: Arlene Foster was last week correct when she stated that her party was not shown a copy of the wording agreed between the UK and EU until late on Monday morning. However, I believe the DUP was, generally, kept in the loop by Mrs May's government. That said, her government did suffer the loss of a minister recently, to be replaced by her chief whip and the appointment of a new whip. Undoubtedly, something was lost in translation, but I believe the DUP was more motivated on Monday by the reaction of David Trimble, former leader of the rival Ulster Unionists and now a Conservative peer, to an inaccurate leak of the agreement to RTE than by any other single factor. Lord Trimble's reaction that he was left "shocked" and "scratching his head" caused the DUP to retrench to shore up its base.
The agreement, as published last Friday, was essentially Monday's agreement for slow learners, with an extra dollop of fudge on top.
But as Fianna Fail leader Micheal Martin told the Dail last Tuesday, the fears and concerns of unionism need to be addressed. From the outset of Brexit, he said, he had been at pains to separate that issue from the question of a united Ireland.
Sinn Fein has sought to conflate the two. But Martin said that Brexit was about the economic well-being of all the communities on this island - the bread and butter of daily lives - and not, as Sinn Fein has advocated, an opportunity to pursue a united Ireland through Border polls or otherwise.
Varadkar has acknowledged this, but perhaps not as strongly as might be expected.
In the Dail and at his press conference last Friday, he has also given the impression of a man intent on continuing to stoke nationalist fervour for political advantage, as represented in the opinion poll.
He would be well advised, however, not to confuse outdated nationalism with a sense of new pride, or even patriotism that he has, unwittingly or otherwise, seemed to tap into. In other words, Varadkar should now set aside the green jersey for the red of the British & Irish Lions.
