From looking glass to perfect mirror image - Dublin-Donegal rivalry has transformed them and their sport
It is seven years since Dublin and Donegal entered the looking glass and it is fair to say that not many, even including a cohort of dyed-in-the-wool Dubs, appreciated the vista of a Gaelic Football world turned upon its head.
Context and timing was all.
Dublin were, at that time, renowned as much for the ever-increasing gap between All-Ireland titles as they were for their increasing ability to find different ways of subsiding at the penultimate hurdle, as they had done four times since 1995.
Summer entertainers but September failures. They had to find a way to win, any way. Donegal had their own fierce motivation, too. They had only ever won one All-Ireland and they were also confronted with a desperate resolve to change their history.
On a remarkable day where the crowd's catcalls echoed a Greek chorus of disapproval, though, it seemed like we were witnessing an historic moment of a quite different hue. This was footballing Armageddon and it seemed like nothing would ever be the same again.
But sport is not like that. As difficult as it may have seemed to grasp at the time, this was part of the game's evolution.
What ultimately emerged, from the short-term springboard provided by Dublin's escape from history in the subsequent 2011 final against Kerry, has been arguably the greatest collective to have ever graced the game.
The journey has not been without its own pitfalls. When Jim Gavin succeeded Pat Gilroy, his personal philosophy conflicted so violently with that of Jim McGuinness's Donegal that it seemed obvious to all the twain could never meet.
Yet defeat to Donegal in 2014 - the evolution of their short revolution - exposed even Gavin to the realisation that there are times when events must trump conviction.
They have never lost a championship game since. As they continue to evolve, others have followed.
Notwithstanding their 2014 peak, we never did got to witness the complete culmination of the McGuinness philosophy due to the premature divorce from Rory Gallagher.
For the latter's suitability as a potential visionary was haplessly manifest, notably two years later, again by Dublin, in their third championship meeting in five seasons.
Now under Declan Bonner's tutelage, this will be the counties' fourth engagement since 2011 and, even in a decade when the competition between Dublin-Mayo has transcended the sport, theirs is a rivalry which can justifiably claim its own significance.
"They have been good for each other and good for the game of Gaelic football," argues former Dublin All-Ireland winner Jack Sheedy.
"If you look at the 'Super 8s' you could make a really strong argument that all of the teams are set up to play football in a more traditional sense.
"That's what the public want to see, teams trying to set up to score more than the opposition, not merely going out with the purpose of damage limitation. For one thing, it isn't good to watch and as we have seen it is no guarantee of success either."
However, just as Donegal had to adapt from the extremities that undid them in 2011, which they managed to do so with a flourish three years later, so too were Dublin forced to modify their own conviction to all-out attack.
If you press him, Gavin will concede that, as devastating as defeat in 2014 might have been, the wound was salted still further because Donegal didn't win the final, Kerry did, by themselves abandoning their traditional game.
And so Gavin's great leap of faith would be to gamble himself on tweaking his approach to avoid a repeat ignominy.
The Dublin manager's admission of his own vulnerabilities would only be judged by how he and team could successfully repair theirs.
"Dublin had to change," agrees Sheedy. "They were exposed that day but learned from it. "It could have been easy to go back to what they knew but they didn't. They did it in the knowledge that perhaps it is not going to happen in the first few months or even possibly the first year.
"But it did and they are still playing the same style of football, more or less, with just one or two tweaks. Some personnel changes have helped that evolution.
"It was a delicate balance between trying not to be beaten and creating that transition from a defensive mode into attack. It takes time to blend but they achieved it quite well. They know they have been successful so it is about perfecting it."
From then on, Dublin would hold their centre-back and, even if their speedy wing-backs got forward, another player would drop; up front, they subtly advanced their style, from the basketball screen to the touchline-hugging full-forwards.
All the while, possession remained key. And they hardened their cynical edge to become the complete package, against whom only the indefatigable Mayo could come close to conquering.
Just as Donegal emerged from the debris of 2011 semi-final defeat to triumph in 2012, so too would Dublin reverse their fortunes within a year of their penultimate slip in 2014.
Declan Bonner had been more than an interested observer in 2012, helming his minors to a stunning success of their own against the Dubs and remarking on the senior side's "juvenile" defending, comments that have never been forgotten within the Gavin camp.
Now in his second spell as senior manager, he becomes the third Donegal man in five years to confront Dublin in the championship.
He will do so with a squad of players hewn not only in his own image but that of the team he wishes to conquer. "Donegal have progressed under Declan," says Sheedy. "They are committed more to attacking style and are looking to play with their heads up.
"They've been probably as good as any team this year and we're talking about Kerry who have played well, but Donegal have been brilliant this year.
"I can't imagine they will change too much This will ask serious questions about where Dublin are and, not to mention, where Donegal are in terms of development. Their style now isn't a million miles away from Dublin's."
And so an intriguing rivalry engages once more, renewed by history. No longer witnessed through the looking glass but in a mirror image that reflects the best of themselves and their sport.