There are so many criticisms to be made of the Northern Ireland peace process that it takes a crisis such as this to bring home just what, with all its imperfections, it has delivered.
Many have reservations about being governed by the former IRA leader Martin McGuinness, or formerly incendiary loyalists such as Peter Robinson. They grumble that the politicians are overpaid, that some ministers are weak.
They point out that divisions remain strong, with Belfast's working classes still almost entirely segregated: not a single one of the dozens of peacelines have been dismantled. There's a lot of self-imposed apartheid. There hasn't been a huge economic peace dividend; a lot of people are depressed that the housing price bubble has burst; almost everyone is insecure about their jobs.
Belfast was never an exuberant city and a lot of people have felt they have little or nothing to celebrate.
Then suddenly the gunfire started again and in an instant we realised what the peace process had achieved – not absolute peace, not perfect peace, but an absence of funerals.
In the bad old days – which lasted for decades – people who switched on the evening television news so often saw bulletins featuring grieving mourners carrying the latest coffins through the streets.
But that changed. With the peace process, no longer did heavily-armed troops patrol the streets training their self-loading rifles at potential sniper points. No longer did heads swivel at the sound of shots or of an explosion; no longer did people feel they had to make long diversions to avoid dangerous districts. Bodyguards for figures previously at risk were made redundant.
Police officers generally stopped checking under their cars for boobytraps designed to blow their legs off. Even the traditional rioting – we sardonically refer to the flying bricks and stones as Belfast confetti – became more of a rarity.
All this happened so gradually that for years we wondered whether the Troubles really were finished. But eventually much of the tension drained and people felt they could relax and drop their guard.
As a journalist based in Belfast since the 1970s, I reported on a great many of the 3,700 deaths. Ten years ago, five of us wrote a book called Lost Lives which described every one in unemotional but heartrending detail.
We wrote: "We very much hope the Troubles are now ending, that no more lives will be lost, and that this volume will stand as a monument to the sheer waste and horror of war."
The death toll did not disappear altogether, but it dwindled. Given the emergence of a political deal in which republicans and loyalists shared power practically everyone concluded that the Troubles were over.
When the news came through at the weekend that two soldiers had been shot, it seemed an anachronism, something from a past age. When it became clear that the republican dissidents were using murder to try to restart the war, people felt sick.
Yesterday Frances McCandless, who helps co-ordinate community activism, summed up the reaction across community groups: "It's not a measured response – it's visceral, absolutely gut-wrenching; people are personally shocked. It's an absolutely unanimous message of revulsion."
Even hardened journalists like myself reacted to the outburst of violence and the three new additions to the death toll with horror. The Troubles were supposed to be history, but now they were making the news again, like a recurring nightmare.
Even those relatively protected from the years of conflict are reflecting the sense of dismay. The sight of grim-faced police with machine-guns, and the palpable tension in the air, are terrifying for many youngsters.
According to my daughter Kerry, a Belfast journalist who has never had to cover the Troubles: "I'm stunned, devastated. It's shocking and cowardly that people are being murdered again by these deluded people. The idea of troops and roadblocks and people being scared to go out just fills me with a sense of dread."
Three funerals lie ahead and no one can be sure there will not be more. The republican dissidents hope to stage more attacks, and it is never too difficult to provoke paramilitary loyalists back to violence.
The dread of reawakening the sleeping giant of loyalism was voiced by Patsy Toman, a nationalist councillor in the Co Down hamlet of Loughinisland. In 1994 Protestant gunmen shot dead six Catholics in a pub there. He said: "I'm just hoping and begging and praying to myself that it doesn't start a tit-for-tat thing. The loyalist paramilitaries still have their weapons and one can feed off the other. It's almost something you don't want to think about."
A community worker on the Protestant Shankill Road – who stipulated, "Don't use my name, it could get me shot" – reported an ominous mood in the loyalist stronghold.
"There's nearly an acceptance here that there could be retaliation," he said. "Most people wouldn't want to see it, but there's just an expectation – it's part of the culture here."
Given that grim old pattern, no one can be sure that this present outburst will not develop into a cycle.
Yet there is a powerful and growing sense that a few gunmen are not going to trigger the destruction of the political settlement and the peace process. This is because this glimpse of the bad old days has produced not fatalism, not acrimony, but a new appreciation of the value of peace. In the old days security crises often led to political recrimination. Not this time: terror has lost its usual centrifugal effect. Yesterday, two men called the gunmen "murderers". One was Gordon Brown, the other was John O'Dowd of Sinn Fein: never before has there been such a consensus.
Mr McGuinness went further, labelling the dissidents "traitors of the island of Ireland", while he and Mr Robinson are standing side by side in defiance of the efforts to divide them.
The peace process is being severely put to the test: yet the signs are that, with such visible determination to protect and maintain it, it is going to survive. It does the heart good to conclude that the killers will not win, and that the peace will prevail.Reuse content