James Lawton: Players and manager conjure up brilliant performance that will live through the ages
While Italy's Antonio Conte projected a fantasy, Martin O'Neill nursed his embattled dream that Ireland could make it through to the most serious action.
The dream came about - as it did for his predecessor Jack Charlton in Giants Stadium in 1994 - and this morning there is a wonderful dawning reminder that sometimes a superb reality is just a heartbeat away.
Conte, who stood between Ireland and the high-profile collision with France in the round of 16, had another, fancier idea.
It was that his rallying of the Italian football culture was so strong and embedded that he could make eight changes and still carry the aura of invincibility.
He argued his case well, - as did such senior lieutenants as Daniele De Rossi - but it just didn't hold up against the response of O'Neill's men to the call for 90 minutes of the greatest commitment of their football lives.
Sometimes it seemed that the best Irish intentions in the world would perish under the weight of superior touch and instinct and this fate came nightmarishly close when Italian substitute Lorenzo Insigne carved through the Irish cover and shot against a post.
The man from Napoli, who many believe should be a starter but has yet to win over the single-minded Conte, struck in the 74th minute and it was easy to imagine that the Italian second string had weathered the best of the Irish spirit.
Withering confirmation of this appeared to have arrived when Wes Hoolahan, a late entrant to the drama, missed a chance in a fashion that threatened to plague him for the rest of his life.
He had only to beat goalkeeper Salvatore Sioigu, an often frazzled replacement for the relentless Gianluigi Buffon, in the dwindling minutes. But he shot tamely, the danger evaporated, and Hoolahan wore the countenance of a man checking into a prolonged stay in purgatory. It was banished soon enough.
Hoolahan's cross from the right was so sumptuous it overwhelmed even Leonard Bonucci, arguably the most accomplished defender in the world game.
The man from Juventus could only watch the arc of Hoolahan's cross as Robbie Brady headed the ball home with unanswerable conviction.
This was the climax of the dream that O'Neill had cultivated so doggedly against tides of criticism - and a thousand pieces of advice on how best to cultivate his relatively slender talent base.
It was the pay-off for the belief that if you work hard enough, believe in yourselves sufficiently, you might just achieve everything you place in your sights.
It happened against the world champions Germany - and now it has happened against a football organisation which was at pains to point out that it produce a squad of inter-changeable individuals all equipped to compete at the highest level.
Last night the least of Ireland's achievements was to strip down that lordly conviction.
Their performance was less than perfect. Indeed, there were times when it touched upon the ragged, sufficiently often indeed to fuel Conte's theory that he could indeed face Spain with the momentum of the coach with an implacably winning touch.
But if Ireland's rhythm sometimes misfired, if Italy at times cuffed away many of their attacks with the unreal calm of sleepwalkers, there were also those moments when the passion to succeed rose quite inexorably. Jeff Hendrick lashed a left-footed drive which flashed inches wide of the Italian and had that succeeded there would surely have been an explosion of newly installed confidence.
Instead, Ireland prosecuted their cause with undaunted ambition.
Shane Long sneered in the face of Italy's perceived superiority and there was also the possibility that something extraordinary, which perhaps had more to do with the spirit than the deepest reaches of pure talent, would come to haunt Conte's comfortable belief in his own resources.
And so it happened. O'Neill was vindicated not as one of the great football tacticians - a claim he does not tend to make - but as a man-manager who persuades players about the rewards that can come when you give everything you have.
He learned that at the knee of the great football pugilist Brian Clough and at Euro 2016 he has surely made a lasting imprint of the football that has been such a daunting challenge for all those who followed in the footsteps of Big Jack.
Four years ago in Poland, the Ireland of the old warrior Giovanni Trapattoni dwindled before our eyes.
On the touchline Old Trap wore the expression of a man who had carried him team to the very limits of his powers of persuasion. "What can I do now?" the veteran's face seemed to be saying.
Last night in Lille, the demeanour of O'Neill was quite different. It was filled with the belief that, somehow, the job could be done.
That it was, and ultimately so gloriously, spoke of a rare and vital quality.