A noble French man once said the only day you can do nothing about is yesterday. Or in the realm of sporting combat, the first half.
Kerry put a foul first period to one side in Tralee Wednesday night and outscored the Munster and All-Ireland champions Cork 0-12 to 0-3 after the break. Impressive stuff. If such is the cornerstone of future intent, the Kingdom may nurture a handful of these Under 20s into the adult grade.
All in its own time, of course.
The younger brother of Briain Ó Beaglaoich, Ruairi, was the scoring difference in the second period, causing the Cork full back line the sort of difficulties his Cork equivalent Blake Murphy had visited upon the home rearguard prior to the break. Ó Beaglaoich mined four points from play, almost all of his own making, to lead Kerry's revival and claim back the provincial title at the grade.
But the revival was hardly a one-man act.
Paul O'Shea - who we must now cease calling David Clifford's first cousin - has the same languid style of some special Kingdom talents before him, but the greatest impact in this final was his positioning and ball-winning ability in his own half.
Along with Darragh Lyne and Sean Horan, they managed to steady home nerves after a first period blotted with far too many unforced errors, ill-placed passes and head-in-hand misses in front of the posts.
Cork enjoyed an interval lead of 1-6 to 0-5, with St Vincent's Murphy responsible for 1-2.
As defending champions, one would have anticipated a level of authority from them after the break - until we remind ourselves the most of these players are college freshmen.
If there was one Kerry player whose sense of place and direction was accurate throughout the 70 minutes, it was wing-back Sean O'Brien from Beaufort - a rangy do-it-all who looks a prospect to keep an eye on.
But it wasn't all down to the players. Kudos too to new manager John Sugrue and the decisive changes made in the second period. First bringing on Eddie Horan (and repositioning his twin brother Sean behind midfield to stem the Blake Murphy and Mark Cronin threat), and following that with Sean Keane and Sean Quilter, who replaced the well-rated attacking pair of Paul Walsh and Killian Falvey.
Each made a notable contribution to the revival.
Cork? Keith Ricken, though he's seldom of a mind to, will be deeply frustrated at his side's inability to build on a promising first half. Mark Cronin kicked a couple of inspirational second-half points that his colleagues might have fed off, but it never happened. Eanna O'Hanlon. Cronin and Murphy battled on, but the likes of Aodhan Ó Luasa and Brian Hayes had quiet nights in the half forward line.
With O'Shea and Horan augmenting the midfield work of Kerry's O'Gara and Darragh Lyne, Cork never created the goal chance that could have reasserted their superiority. And they failed in the necessary duties of defence.
On 48 minutes Kerry's two best players on the night, the afore-mentioned O'Brien and Ó Beaglaoich combined on the left flank for the Gaeltacht lad to point and create a one-point buffer, 0-12 to 1-8.
From there, Kerry headed for home with O Beaglaoich at the wheel. Paul O'Shea sent him on his way for the killer goal, but the corner forward elected to punch the point and extend the lead to four in the 57th minute, the turnaround complete.