On September 11, 2001, I was about to hold an early afternoon editorial conference in the Belfast Telegraph. Someone suggested we turn on the television in the editor's office as something incredible appeared to be happening in New York.
This day would rank in our lives in the same way as the murder of President John F Kennedy did for millions around the world 38 years earlier.
The question of where were you when Kennedy was shot would become, for a new generation, where were you when the twin towers collapsed.
And, just as with Kennedy, the special editions of newspapers began to roll off the presses everywhere, including in Belfast that September afternoon.
What we didn't realise then, but know now, is that September 11 altered the Western world's perception of terrorism most notably where it mattered most for Northern Ireland - in the Irish-American heartlands across the Atlantic.
As a result, we live in a very different atmosphere today. How times have changed in only one decade.
For example, take this past weekend and Sinn Fein holding its first ard fheis in Northern Ireland at the Waterfront Hall.
I remember attending the civic dinner to mark the Waterfront's opening. Because most guests wanted nothing to do with Sinn Fein, its councillors were diplomatically seated in a corner with editors like myself.
How times have changed. Now we have a Presbyterian minister addressing the ard fheis. The Lord Mayor of Belfast is also a member of Sinn Fein. He was a teenage boy on 9/11 and not even born to experience the worst of the Troubles.
How times have changed. I thought that, too, as I looked out over a rain-swept Belfast one Friday evening this month. The word normality sprung to mind - and not only because of the weather.
From my vantage-point, I could see three sets of floodlights beaming through the dusk. To my left, in the west of the city, the lights of Casement Park, more centrally, those at Windsor Park, and over on the right, Ravenhill.
Belfast was out on the town and at play, a far cry from the days when hardly an entertainer, or sportsperson, would dare to come to Northern Ireland and the city was a cultural desert.
The following day I stood with tens of thousands enjoying the Portrush Air Show and, in the evening, attended the Clandeboye festival, where the packed audience gave a standing ovation to the inimitable Barry Douglas and his Camerata Ireland musicians.
How times have changed, indeed. But would it really have been like it is today if 9/11 had not happened?
The attack on New York proved to be a catalyst for those who wanted to reject violence, as so many did in Northern Ireland. The events of 9/11 made terrorism the dirtiest word on Earth and no more so than here where it had destroyed so many lives, businesses, jobs and property.
As the world looked back yesterday at that cataclysmic event, we who had experienced terrorism for so long had more reason than most to remember not just the victims of the twin towers, but those who died through violence much closer to home.
For every victim in New York, this small province had one also. For every family that mourns to this day across the Atlantic, there is another here doing the same; feeling no less pain, suffering no less loss.
Had September 11 not happened, I wonder would we be as far advanced in the peace process. Might the political parties have procrastinated for years over the decommissioning of IRA weapons, or any number of other obstacles to a lasting peace?
In reality, the terrorist game was up the moment those planes crashed into the towers. Toleration of terror lay buried in the rubble of New York.
The heat in the kitchen had become too great. Only the old republican diehards - the so-called 'dissidents' - have closed their ears and eyes and stayed put.
The smart guys in the Irish republican movement, such as Gerry Adams and Martin McGuinness, swiftly understood the message of 9/11.
Osama bin Laden had given them an unassailably persuasive argument to use against any hardliners. The notion that bombing and killing in Ireland is an honourable cause worth a dollar in a charity bucket in some Manhattan pub belongs to yesterday.
Out of the terrible evil we all witnessed on 9/11, some good has come in this small corner of the Western world.