As Irish-Americans like everyone to know, they love having something to celebrate - one reason why, when New York's sons of Erin marched up Fifth Avenue to mark St Patrick's Day, it was just possible to wander through the crowd and believe that the merrymakers were aware that this year, for the first time in a long time, there was something truly worth toasting.

It wasn't the lapel pins urging strangers to "Kiss Me, I'm Oirish" that brought a hopeful smile. And certainly not the spirit of a tribal get-together that manifests itself, year after year, in the plastic ectoplasm of souvenir dealers' hearts and shamrocks.

Not the green beer, either, nor even the red-haired toddlers, all freckles and snub noses, done up as leprechauns - although as the upcoming generation of Irish-Americans, those kids perhaps stand to gain the most from the watershed change of heart that the past few months have witnessed.

Finally, after at least a century and a half of revering half-truths and starry-eyed lies about brave rebels and perfidious Albion, Irish-Americans may just be prepared to acknowledge that the murderous realities of the land their forefathers fled demand a little more insight than can be gleaned from romantic tunes about the men behind the wire.

And more importantly, to admitting the role Americans have played in making sure Belfast's body count continued to grow.

Actually, the most encouraging indication of a break with the past was to be found not in New York, but in an empty chair in Senator Teddy Kennedy's office in Boston, a few hundred kilometres to the north. That was where, up until this year, visiting Sinn Fein leader Gerry Adams could count on holding court as an honoured guest.

But not this week. This time Senator Ted slammed the door in Adams' face, told him to take a hike and not to return until the IRA, of which Sinn Fein is the political arm, honoured its 1998 promise to lay down the guns.

It is almost unthinkable that it could have happened, that the Democrat elder who represents the largest and most assertive Irish-American constituency in the country, should side with bitter enemy George W. Bush, who cancelled Adams' customary invitation to the White House.

But happen it did, and the consequences of both men's decisions could help to liberate Northern Ireland from its addiction to violence - and Irish-Americans from the curse and corruption of their own sympathetic myths, for it has long been a basic truth that Irish Catholics fire the bullets Americans pay for.

The classic example: at the turn of the last century, the world's first practical submarine was designed and built in New York by a former Christian Brother from Galway, John Phillip Holland, who wanted it shipped across the Atlantic and unleashed against the Royal Navy.