Whatever anyone's feelings about the Ulster Covenant - the centenary of its signing will be commemorated by a huge demonstration in Belfast tomorrow - there is no doubting its seminal importance in the history of the island of Ireland.
Led by the charismatic Edward Carson, around 500,000 people pledged an oath against the imposition of Home Rule and thereby created an indelible mark on the history of British-Irish relationships.
It was the clearest possible demonstration of the strength of feeling among unionist people of what being British meant to them. Some might argue that defying the will of Parliament was a strange way to show allegiance, but the Covenant, and the subsequent enlistment of 100,000 men in the Ulster Volunteer Force, showed that union with Britain was a deeply ingrained instinct.
To mobilise so many people on the one day at a time of poor communications and even worse transportation was an astonishing feat. And the sheer scale of the turnout forced the Government to admit it could not ignore the will of the unionist people. The intervention of the First World War creating a new battlefield, in which the cream of Ulster and Irish men perished, perhaps prevented the opposition to Home Rule taking a more sinister turn.
While Carson opposed the partition of Ireland, which was an unintended consequence to his opposition to Home Rule, he is still lauded by unionists as the creator of Northern Ireland. For them the anniversary of the signing of the Covenant is a hugely emotive occasion and hopefully all those taking part in tomorrow's demonstration will approach it with the solemnity which accompanied that long-ago declaration. For those who oppose what the Covenant stood for, they should stand aside and allow its supporters to have their day.
Perhaps Carson would find some solace in the new political arrangements in Northern Ireland where various cultures and traditions are largely tolerated and respected. We have still some way to go before we have a truly shared society but certainly the outlook is a lot less apocalyptic than it appeared a century ago.