Italia '90 was the best thing that ever happened in the history of Ireland.
That's not a debating point, it's just the truth, and the only thing up for discussion today is whether it would have happened without Big Jack.
No, is the answer to that one.
Again, we don't need to be annoying ourselves here with mere speculation - indeed, one of the many things that Jack brought to the party, was this sense that to be indulging in hypotheticals was for the birds.
Would David O'Leary have been better than Mick McCarthy? That would be a very interesting question for The Moral Maze on BBC Radio 4, meanwhile, the gaffer was trying to win football matches - or draw them anyway, which was sometimes the same thing.
He was great for us, was Jack, he brought a kind of clarity to our dreaming, a kind of certainty to our meanderings. And he even brought a bit of luck that we had been lacking for generations.
Yes, he spoke his mind - when I interviewed him just after he'd got the job, he told me he was disappointed that I wasn't a woman, because the interview had been arranged by a woman in Hot Press, so why wasn't I a woman?
He had me there.
He got over it though, and rattled off a fine stream of Charlton consciousness in which Bulgaria was Romania, and Paul McGrath was John - he was wrong but he was strong.
He was right though, when he called for the land to be taken off those farmers who were habitually dumping their slurry into some of our great lakes - he made no trivial factual errors there, it was an issue which spoke to the deepest part of Jack the angler and countryman.
Jack was great for us, but we were great for him, too - not only had we some unpolluted fishing grounds, and a few decent footballers, we respected him rightly as an actual World Cup winner, one of the Boys of '66, whereas England hadn't even replied to his application to be their manager.
And when he went looking through the English leagues for our "great-grandmother" players, he ended up with a team we could all identify with - the British pundits had their banter about "drinking a pint of Guinness and finding yourself playing for Eire!", but Jack's team was absolutely Irish in the most meaningful sense - for what is more Irish than the sons or grandsons of emigrants finding their way back home?
That was just the players - the supporters found their way to Stuttgart and to Hanover and to Gelsenkirchen, they found their way to Cagliari and to Genoa and to Rome.
And none of us gave a damn that Jack was English, no more than we minded that Lester Piggott rode for Vincent O'Brien, or the myriad other examples of Irish people being successful with a bit of help from across the water.
We loved him.