The crisis that has overtaken the Mitchell review of the agreement is not a technical hitch but a problem of principle. The review was itself the last chance to save the peace process, and this is the last chance to save the review. Mr Trimble is a somewhat unlikely figure to be confronted with a choice between light and darkness, order and chaos, in the closing weeks of the 20th century. He is a leader of stiff integrity who prefers detail to vision, tactics to strategy. He is, in short, like his own people.
The failure of the agreement would not necessarily plunge the province into an immediate resumption of armed conflict. But where there is no longer any map for the future - no progress to look forward to but only an endless and bitter stalemate full of despair and recrimination - the forces of hatred and violence will quickly move in and take charge once more. But it would not be fair to Mr Trimble to minimise the difficulty of his position. He has rightly said in the past that a false peace is no peace. Based on deceit it would be morally offensive, and it would not endure. Those with whom he has to conclude this peace now have been the sworn enemies of all he believes in. According to his lights, they were not just groups with whom he had an honest difference, nor even people who have been foolish, misguided, misled. They were treacherous schemers, liars and murderers, tainted not just with crime but with evil.
Are they still? What is most remarkable this weekend is the way the evidence is piling up that David Trimble has finally changed his mind. He has reached the point of thinking that Sinn Fein, even the IRA itself, are people he can do business with - and who genuinely want to do business with him. Furthermore, it appears that a good majority of his Unionist fellow assemblymen are prepared to agree with him. More than most politicians, those in Northern Ireland like to use their mouths more than their ears. Senator Mitchell seems to have achieved the miracle of getting the Ulster Unionist leadership actually to listen to Sinn Fein. What they heard told them that the republican ideology of armed struggle really was spent at last. Sinn Fein/IRA is no longer committed to "bombing a million Protestants into a united Ireland"; it no longer holds a gun in one hand and a ballot box in the other. It wants to come in out of the cold, and it wants Unionist help to do so. It wants, in short, to enter into power-sharing - a step which would surely lock it into a renunciation of violence more completely than the totem of decommissioning could.
To seize the moment, Mr Trimble has to ask the Ulster Unionist party to act out of character. It has long practice in saying No on behalf of its sectional interests, none in saying Yes on behalf of the whole people of Northern Ireland. Probably his deputy John Taylor is right to say that there is nothing tangible on the table that has not been there before, even if that "nothing new" is for the first time contained in a statement direct from the IRA. It would be much easier for Mr Trimble if he could refute Mr Taylor with a few hundredweight of decommissioned Semtex. What he has to offer instead is the beginning of trust, which sceptics, cynics and false patriots will be eager to tear down. Trust is less dramatic but, in the long term, far more relevant to Northern Ireland's future.
Decommissioning had always been insisted upon by the Unionist side precisely as an alternative to trust, even as a public declaration that there was no possibility of trust. To that extent, decommissioning was backward- looking, based on the assumption that nothing had really changed. It assumed that the only reason the IRA would stop wanting to murder people was because they no longer had the means to do so. It was, of course, an illogical theory: a disarmed IRA could rearm virtually overnight, if it chose to do so.
Although it was incapable of precise definition, the Unionists insisted on making decommissioning the one non-negotiable element of the process. Some prominent Unionists may even have pretended to back the agreement knowing that the decommissioning issue gave them the means to frustrate progress whenever a settlement seemed to be getting too close. The suspicion of that has proved an effective way of undermining trust in Unionist good faith on the Nationalist and Republican side. Mr Trimble has heard these fears, really heard them, for the first time. And he has made the necessary response. He may not emerge victorious in the final battles ahead; but he has already earned his Peace medal twice over. Now he has to do so yet one more time. No reasonable person could want him to fail.