"I'M not boring you, am I?"
Dessie Ryan is in an equipment room in the clubhouse of Ballinderry Shamrocks, describing the moment when the very first sweeper system was devised for a game between Queen's University – of whom he was manager – and the reigning Sigerson champions St Mary's.
This is the football coaching equivalent of the Dead Sea Scrolls, given how reticent Ryan is normally to granting interviews. Yet it shows how humble he is when he asks, "I'm not boring you?"
Today, he will be in the management team of Ballinderry Shamrocks when they face St Vincent's in Newry, a place in the All-Ireland final at stake. The Shamrocks know how lucky they are to have such a guru involved.
But first, back to the story.
Ryan was part of a Queen's management of 1990 with Sean O'Neill and the late Paddy O'Hara when they met the Ranch early in the season, losing by 18 points. By the time the Sigerson came around, Jarlath Burns and Fergal McCann were busting down barricades in midfield as the Ranch engine room.
Ryan did a simple thing. He stationed Colm Hanratty at centre-forward and instructed him to stay in the midfield.
"They were looking to beat this Queen's team by 18 points again," recalls Ryan.
"I said to Collie Hanratty, 'You stay in the centre.' He was centre-forward but I wanted him to stay. That day, Jim McKeever and Peter Finn were the two men in charge and we thought if we gave them a problem, they wouldn't be able to fix it within the hour.
"We ended up beating them," he finishes, but in case you thought he was being boastful, adds; "Course, weather was a big factor too."
The rest really is in Ulster history, a book waiting to be written. Some of the more persuasive Armagh players on the Queen's team introduced it at a county level and from such scratch ingredients the blanket defence became both accepted practice and possibly the major coaching innovation of the last two generations.
The endgame – Donegal's formation against Dublin in the 2011 All-Ireland semi-final – horrified Ryan.
"It was alright for a while, psychologically they had Dublin but they backed down. Murphy, the best forward in the country staying around midfield in the second half? Who was going to score? Ah, it bothers me yet."
As another strand to the story, that was the first time a psychologist – Dr John Kremer – had a role to play with a Gaelic football team, at least in Ulster.
An extraordinary yarn, but it's only a minor detail in an incredible life.
For example, on Monday night a 'True North' documentary (BBC NI, 10.30pm) will focus on Ryan's life-long friend Patsy Forbes and his athletics career.
The documentary was initially intended to focus on both men before Ryan injured his Achilles prior to the World Championships in Turin last year.
Forbes is in the middle of a streak of form, winning two medals in Turin, the Irish Championship and a couple of distances in the English Championship.
Ryan won the British Championships a couple of years ago at 100, 200 and 400 metres. He ran his 100 metres in 14.06 seconds. He is 74 but glows with a tan and vitality.
The two men train religiously on Mondays, Wednesdays and Fridays but if you go into Magherafelt Centre on a Saturday morning, you will spot them out on the track doing 'extras'.
When he was a younger man, he played football for Kinturk, outside Cookstown in Tyrone.
He played for the county minors and graduated straight away to seniors, playing on the first Tyrone team to win the McKenna Cup in 1957.
On February 5, 1958 he left to go to New York. After a few years sampling life in the bars and on construction, he landed a job with the Fire Department, one of only five Irish-born men in their ranks. You had to be a citizen of five years, and the age limit was 27. He got one go at the intake and made it.
"Luck", he says. Not likely.
He played for New York in a couple of National League finals, becoming the first man from Northern Ireland to represent them and his selection for the 1966 final against Longford was blocked by a figure in New York GAA. It led to resignations of some administrators.
Along the way, he was deeply involved in two of Ballinderry's three-in-a-row of Derry Championships in the early '80s. Altogether, he has been with them for nine Championship seasons and they have won the Derry Championship each time.
Yet he agonised over making a commitment to them.
"I had purchased a pub in Ballyronan and I remember Adrian McGuckin had come up," he recalls.
"I wasn't sure about it even though I was living in Ballinderry because we live on the borderlines of Ballinderry and Moortown and we were as near to Ballinderry and we went to Ballinderry church, would have played with Ballinderry minors, maybe not just legally at times! As things happened in bygone days ... "
His role on the training field is discreet yet telling. He chips in with the odd interjection, or brings players away to show them the virtue of taking a shot for goal fast, rather than allowing the space to be swallowed up by the goalkeeper.
Or he might show how to jockey a forward, using his momentum to keep you in his immediate vicinity.
Some say he leans on American sports for this level of detail. He shrugs it off and says it's mainly things he hated been done upon him when he was a player.
In Ballinderry, he found his ideal home, where skills are practiced and valued.
When they take the field today, there will be a host of some of the most gifted footballers to emerge from Derry in their lifetimes.
All of them bearing the stamp of Dessie Ryan.