I called 1972 the 'Telling Year' because it was the year that should have dispelled all illusions about Northern Ireland. What was telling about it? It was not just the worst year of the Troubles, but it encapsulates all the elements of that whole grisly period and even of the ultimate resolution.
We learnt everything we needed to know about our communities that year; that they were capable of producing and excusing extreme barbarism. We learnt also that there was a limit on the potential for violence and chaos.
It is almost impossible to recover a sense of what Belfast was like that year. The city was a different shape; there were large housing areas in which all homes were small and tightly packed together without gardens.
Many of our main roads were narrower. The Westlink hadn't been built. Republicans were campaigning against the plan because they said it would divide Catholic from Protestant.
Many people professed themselves entirely bewildered by the eruption of violence. One theory that had some currency was that the Russians were stoking it up for the sake of creating a Cuba off the coast of mainland Europe.
That same denial of reality applied to the coverage of many of the killings, in particular to the determined refusal of many to believe that loyalists were killing innocent Catholics.
Catholics were similarly denying anti-Protestant sectarian killings and killings by the Army were overlooked and absolved by the state and much of the media. One big lesson of the year was that an army cannot be trusted to behave, but those who needed to learn it didn't want to.
The Rev Martin Smyth, later to be Grand Master of the Orange Order, claimed that the trouble would stop immediately "if the Bishop of Rome put his house in order".
Bernadette McAliskey gave an interview in the September issue of Playboy in which she argued that an independent and socialist Ireland would sustain itself from its mineral wealth.
This was the year in which the British government and the IRA first entered negotiations. They devised a trade-off of prison reform for a ceasefire.
The secretary of state William Whitelaw agreed to phase out internment and give political prisoners 'special category status'.
These concessions were communicated to Gerry Adams and Daithi O Conail at a meeting with the diplomat Philip Woodfield in Donegal. On behalf of the IRA, Adams and O Conail sought to negotiate the right to bear arms and patrol their own areas during the coming ceasefire.
There is no record that the government assented to that, but the IRA assumed the right anyway and the meeting planned with Whitelaw went ahead - even though the overall level of killing actually increased during the two weeks before the ceasefire broke down as loyalists and the Official IRA - themselves nominally on ceasefire - increased sectarian attacks. The Provos opened fire on people who tried to evade, or didn't see their roadblocks.
The important concern for the government was that the IRA was not shooting at soldiers. It was a telling year for unionism, too. With the Unionist Party's loss of authority, new contenders for the leadership of northern Protestants emerged.
A former Minister of Home Affairs, William Craig, drilled his Ulster Vanguard volunteers and swore that they would "shoot to kill". He claimed his organisation was compiling a list of targets and would act if the government did not take off the kid gloves.
The Rev Ian Paisley formed the Democratic Unionist Party and initially campaigned against Vanguard's tilt towards Ulster independence by demanding full integration of Northern Ireland into the UK. It was in 1972 that the basic idea by which the Troubles were ended was devised.
This was that nationalists would be given a share of executive power. And the talks reached this idea without the major nationalist party, the SDLP, taking part. They were still boycotting talks in protest against internment.
Another element of the solution raised its head, too, with Daithi O Conail of Sinn Fein seeking partnership with the SDLP to press for a solution. What hadn't occurred to him then was that his own party still had only negligible clout and that a pan-nationalist approach could only produce an SDLP roadmap for peace unless Sinn Fein started fighting elections and taking seats.
The Telling Year of 1972 showed Northern Ireland at its worst, showed the paramilitaries and the Army at their worst. But, after a year in which all were at the peak of their killing, the violence declined and though thousands more would die and decades would pass before a solution, the level of carnage of that year would never be attained again.
That raises two questions for historians: why did the trouble go on for so long after the outlines of a solution had become clear? And why, with such passion for mayhem and destruction, did no side ever push Northern Ireland over the edge?
What was tearing this place apart seems obvious; what held it together is still a mystery.