As Samuel Goldwyn famously said, a verbal contract isn't worth the paper it's written on.
Ulster Unionists concede there was no written guarantee from the republican movement during the Mitchell review to begin decommissioning by the end of this month, but they felt they had an understanding that the weapons would be going into the grinder soon.
That's not the way you do business with the IRA, as any experienced official in the British or Irish governments could have told them. True, republicans have a way of intimating that if certain concessions were granted to them, gestures from their side could become a live possibility. But their words need to be parsed with care lest the wrong interpretation be drawn.
This appears to be part of the tragedy which is now unfolding in Northern Ireland. Genuine and sincere unionists got the wrong end of the stick in negotiations and made an excessively liberal interpretation of what was on offer from the republican side. They were not helped by a widespread view that, since decommissioning was the right thing to do, the IRA would have to do it soon.
There was also an excessively cynical view of Sinn Fein's participation in the new Executive: there is no convincing evidence that republicans would do just about anything to keep the perks and trappings of office. Maybe, in time, fat will start to accumulate on their principles and Sinn Fein members become as venal and self-serving as some of their historical predecessors, but that is not the position at present.
Another aspect of the tragedy is that both unionists and republicans are enjoying their ministerial posts: not the plush offices and accoutrements but the opportunity to put their policies into practice, to make a difference to the daily lives of ordinary people. The Executive has worked well, broadly speaking, which will make it all the sadder if the powers granted under devolution now have to be withdrawn.
Unionists take satisfaction from having demolished a number of myths in the past eight weeks. The taunt that, to quote a former unionist leader on Catholics, they wouldn't have one about the place, can no longer be made with any conviction.
All external appearances suggest that the mainstream unionist leadership has entered the power-sharing arrangement willingly and in some cases with gusto. The myth that they would try to undermine the North-South bodies from the first day has also been scotched, as nobody has been more enthusiastic or high-profile in this respect than the Minister of Enterprise, Sir Reg Empey.
But for all their outwardly healthy appearance in the past two months, there has been a cancer eating away at the new institutions, decommissioning. Senior unionists were reportedly told by high-level security figures some time back that the decommissioning demand had no value in the fight against terrorism.
There was also plenty of evidence, if anyone cared to study it, that it would be difficult if not impossible to wrest the weapons from the hands of those who have fought perhaps the most bitter and sustained campaign of guerrilla violence the western world has ever seen. Now it seems the carnival may be over: the merry-go-round is slowing-down, the music has stopped and the lights are going dim on a unique political experiment. The Ulster Unionist Party leader has tabled a motion to discuss the various de Chastelain reports in the Assembly on Tuesday afternoon, the Patten report will be the subject of a special meeting of the party executive the following Monday and, overshadowing everything, there is the UUC gathering planned for February 12th.
We told you so, the dissidents in both the unionist and republican camps can claim. Adams and McGuinness thought they could take the helm of republicanism after 200 years of violence and steer the vessel towards peaceful democratic politics.
Trimble thought he could lead the mass of his party into coalition with nationalists and republicans, and in the process shore up the link with Britain and bring violence to an end. But he failed to hear key elements of his party insistently stating that, in the words of the old John Lennon song, "Nothing's going to change my world".
Despite the gloomy outlook prevailing in Belfast this weekend, all may not yet be lost. Doubtless there is frantic activity going on at political, diplomatic and governmental level. London and Dublin have been criticised from time to time for a "crisis management" approach to the peace process, but there can be no disputing that there is now a crisis and it needs to be managed.
Gen de Chastelain's report is due on Monday afternoon, and no doubt he is benefiting from the collective wisdom of the two governments in its preparation. After all the spin and hype of the past three months, it now appears he will not be able to report the destruction of IRA weapons.
Apart from that, it would be surprising if he did not employ the most constructive language available to describe the situation. It is known, for example, that the general accepts the bona fides of Adams and McGuinness as peacemakers doing their best in a difficult situation, but he will presumably have to accept that the two Sinn Fein leaders are unable to resolve the weapons issue at this stage. Be patient, give us two years in office, let our support base and the community as a whole see the experiment working, and then we will deal with the guns: that is the plea from republicans. But it appears to be falling on deaf ears in the unionist camp.
It is now axiomatic with many unionists that republicans are making all the gains while unionists receive nothing. The modification of Articles 2 and 3, the acceptance of a unionist veto on the constitutional issue, the moves towards a peaceful and democratic dispensation and the general lack of violence don't seem to have registered with some unionists who seemingly would prefer the certainties of being under siege to the doubts and complications of doing normal business with an old enemy.
The British government's decision to accept the main recommendations in the Patten report has caused major upset to unionists and is contributing to the present uncertainty. In a famous dig at Sinn Fein, Seamus Mallon described the Good Friday negotiations as "Sunningdale for slow learners", but there are many unionists who are having difficulty coming to terms with the changes required if they are to live in peace and harmony with their neighbours.
Even moderate unionists, who may see the logic behind the changes, are finding it hard to accept them on an emotional level. Whatever the detail of the implementation of the Patten report, the dropping of the RUC name and virtually-certain depoliticisation of the force's insignia have come as a shock, even though they were implicit in the deal negotiated on Good Friday.
This week David Trimble will do what he has to do, and that may include offering his resignation. A nationalist and republican backlash is likely against a perceived unionist "coup" to overthrow the new institutions. Brian Cowen will have a baptism of fire in his new job as Minister for Foreign Affairs. Perhaps he can come up with something, because at this stage everyone is running out of ideas.