IT was, I think, a Turkish prime minister who said: "Never cheat when you are dealing with terrorists. They don't understand it." He was talking about negotiating a successful outcome to an emergency such as the hijacking of an aircraft, but his words have an urgent relevance to the scenes of last night in London, and to how our leaders act in the critical days ahead.
There was always a danger, as the weeks became months and the months stretched into a second year, that we would come to take the miracle of pence for granted.
I feel as guilty on this score as any of the politicians charged with turning the ceasefire into a lasting settlement. Whenever I talked to men and women in the Sinn Fein leadership - those who struggled to bring the violence to an end in August 1994 - it was clear that they were coming under increasing pressure, that the patience of many of their grassroots activists was running out, and also that they were determined, at all costs, to avoid a split.
It was shamefully easy to lose sight of that central fact, to become obsessed instead with the byzantine manoeuvres of the political situation: the importance of the latest quarrel between Dublin and London; how the unionists might be persuaded to move; whether Sinn Fein would be persuaded to sign up to the principle of consent in the peace and reconciliation forum's report; why John Major had decided to endorse elections; how the Clinton administration would react to the many and varied claims on its attention by politicians from both parts of Ireland. And so on.
What those terrible familiar scenes on Canary Wharf last night have made clear is how we have failed to create, in many of those who believed change could be achieved only by the bomb and bullet, any real confidence in the political process.
Gerry Adams warned, to the point of boring many people, that if the peace was not seen to yield results, the process could collapse. A5t that there were the happy crowds shopping in Belfast, President Clinton switching on the "Christmas tree lights, Van Morrison promising Days Like This. A return to violence seemed unthinkable. It was, easier, instead, to dismiss the Sinn Fein leader as crying wolf.
Last night BBC Northern Ireland mounted a special programme which featured the reactions of many politicians and pundits. It also sent a reporter to talk to "ordinary" men and women on the streets of west Belfast.
Most people were, quite simply shellshocked - and frightened of what lies ahead. What I will remember is the young man who said: "It's brilliant. We never got a bloody thing from the Brits." He pointed to the green ribbon off Saoirse, the organisation for republican prisoners, which was pinned to his lapel, and (assuming that we would all know what he was talking about) said: "What has the peace process done for them?"
Many of those in what Gerry Adams describes as the republican family feel that they have been cheated, on the release of prisoners and many other issues. Over and over again they have said that the IRA delivered what was demanded of it - an end to the violence - that it was promised it would be brought into the political process and that instead, the British government found new obstacles and excuses for reneging.
It is still much too early to say what triggered the IRA decision; whether the British government's cavalier treatment of Senator George Mitchell's report and John Major's speech in the House of Commons combined to provide a bitter last straw.
For many nationalist politicians it looked like yet another example of British perfidy. But politicians, even when they are angry and shout abuse at each other, understand that other politicians duck and weave and renege on their promises. Terrorists don't; though they often learn as they become accustomed to the political process.
None of this is meant to condone or excuse the Canary Wharf bomb. At the very least it was an appalling attack on innocent people, and a major setback for the peace process. At worst, it could be the beginning of a tragedy for another generation.
Thousands of words will be written about the causes and political fallout from the IRA's announcement. But just now the most important thing is to try to keep this sad day in proportion.
When I heard the news last night, what flashed through my mind were images from other parts of the world where political leaders have struggled against terrible odds to bring peace - South Africa, the Middle East.
What men such as Yitzhak Rabin, F.W. de Klerk and Nelson Mandela have had in common has been an absolute determination not to be deflected from the path of dialogue and reconciliation by violence. We have to pray for our politicians to summon the same courage.