There's an old joke about a plane coming into Aldergrove, with the captain telling the passengers: "We are arriving in Belfast. Now put your clock back 50 years."
Let's make that 100 - as the Orange Order prepares to celebrate tomorrow the moment of sectarian revolt against Westminster a century ago, which signalled the onset of a decade of violence.
Demonstrating the fragility of the power-sharing ethos of the new era, Peter Robinson and Mike Nesbitt sought this week to influence the impartial body democratically empowered by Parliament to arbitrate on parades.
Separately, Martin McGuinness visited the Parades Commission in the cause of the Catholic residents of Carrick Hill, abutting the route of tomorrow's march.
Mr McGuinness said the right thing about the rule of law, which his party endorsed in 2007.
There is nothing to celebrate about a movement which defied the rule of law in 1912. It only encourages those - be they marching orders, or 'dissident' republicans - who would do the same today.
The Ulster Solemn League and Covenant wilfully misrepresented the Home Rule Bill introduced at Westminster that year as a "conspiracy", to justify resort to "all means which may be found necessary" to defeat it.
Whatever its merits, or demerits, a secret "conspiracy" Home Rule certainly was not: it had been openly and endlessly debated since the mid-1880s. Yes, there were risks to freedom of conscience in a Home Rule Ireland, as evidenced by the abuse of children and single parents in institutions under Church control in the Irish state.
Yes, there were risks to export markets for Belfast industry, were protectionist policies to be introduced, as from the 1930s to 1950s they (unsuccessfully) were.
And it would have been much better if the progressive, contemporary idea of "Home Rule all round" had been agreed. This would not have set Ireland apart and would have granted devolution to Scotland and Wales early in, rather than at the end of, the last century.
But nothing could justify sounding the drumbeat towards carnage which progressed through the launch, at the beginning of 1913, of the Ulster Volunteer Force, followed by the Irish Volunteers, the Easter Rising, the War of Independence, the civil war and the sectarian cauldron which was the establishment of the Northern Ireland state.
That state was immediately to override the rule of law through Special Powers legislation, allowing internment. It sought to incorporate paramilitary-style Protestant manifestations through the Ulster Special Constabulary.
Paramilitarism thus remained an undercurrent. Lest we forget, it was the latter-day UVF which was to set in motion an even more vicious cycle of violence in the 1960s, with the Malvern Street murders in Belfast and the detonation of devices at public installations - blamed on an IRA discredited by the 1950s border campaign - to undermine the mildly reforming Stormont premier, Terence O'Neill.
One beneficiary of that instability was Ian Paisley, whose associates were linked to the Ulster Protestant Volunteers (UPV). Paisley's long-time deputy will be seeking to place himself centre-stage tomorrow.
Don't forget his conviction for unlawful assembly for leading a demonstration, which attacked two gardai, as well as a Garda station in the Co Monaghan village of Clontibret in 1986.
Or that he presided alongside Paisley, wearing a red beret, at the launch in the Ulster Hall a few months later of Ulster Resistance, members of which engaged in gun-running from South Africa in partnership with the UVF and UDA.
Northern Ireland's troubled past will only become history when its leaders, regardless of their former lives, continue to strive towards that which is universally recognised as a normal society.