The Tunisian revolt could inspire its neighbours, writes Gwynne Dyer.
The analogy might be with the chain of non-violent revolutions that drove the sclerotic Communist regimes of Eastern Europe from power in 1989. Or then again, it might not.
Many people in the Arab world hope the revolt in Tunisia will become a genuine democratic revolution that inspires people in other Arab countries to do the same thing.
Other people, notably most of the existing regimes in the Arab world and their foreign allies, hope fervently it will not. But the situation is fraught with possibilities.
It's not yet clear whether the street demonstrations that drove the Tunisian dictator, Zine al-Abidine Ben Ali, into exile after 23 years in power will lead to a genuine democracy. The Prime Minister he left behind, Mohammed Ghannouchi, is promising free elections soon, but it's still the old regime, minus its leader, that is making the promises. They may not be trustworthy.
This was a spontaneous uprising, an outburst of exasperation with the corruption and incompetence of the Ben Ali regime. The rebels have no plan for what happens next, and several hundred thousand people with guns and good communications facilities have a lot to lose if the old regime just vanishes.
It is estimated, for example, that one in 40 adult Tunisians works for the secret police.
On the other hand, miracles do happen. The East German Communist regime in 1989, after 44 years in power, controlled not only the army but also a well-armed Communist militia several hundred thousand strong. Yet when the Berlin Wall came down, they just decided not to start killing their own people. No matter how loyal they were to Communist ideals, they understood their time was up.
Many of those who served Ben Ali's dictatorship will not want to start killing their own people on a large scale either.
And no ideology underpinned the Tunisian regime. Those who gave it their loyalty did so only out of self-interest, and their perception of where their interests lie could change quite fast.
So the question arises: if the Tunisian revolt turns into a real democratic revolution, could its example spread?
The neighbours think so. Muammar Gaddafi, Libya's ruler for the past 41 years, was almost comical in his public dismay at Ben Ali's fall. "You [Tunisians] have suffered a great loss," he said in a speech broadcast on Libyan state television. "There is none better than Zine [Ben Ali] to govern Tunisia."
Or more precisely, none better to keep Gaddafi safe from his own people.
Tunisia's neighbour to the west, Algeria, is even more vulnerable to popular revolt than Libya. The President, Abdelaziz Bouteflika, has been in office since 1999, but he was put there by the army, whose senior generals have really run the country since the mid-1960s.
Algerians have begun demonstrating publicly against the high price of food, and the regime's response has already turned violent.
The social and economic conditions that made Tunisia such a tinderbox prevail in many other Arab countries - widespread poverty, huge unemployment (30 per cent of the under-30s in Tunisia, and higher among those with a post-secondary education). And popular anger at the authoritarianism and corruption of the regimes.
The strict censorship of news that has always been standard practice for the more repressive Arab regimes has been subverted by new media, from al-Jazeera to the internet. Everybody who wants change has seen how easy it was to make it happen.
Egypt, Syria, Morocco - in fact, almost all the Arab countries except the oil-rich Gulf states - are potentially vulnerable to a Tunisian-style revolt.
Some of the regimes are much more capable of using massive force than Ben Ali's ramshackle dictatorship.
So the big question is: what would the successor regimes look like?
In Tunisia, if all goes well, it could be a secular democracy, but in many other places a strict Islamic regime would be a much more likely outcome.
The old leftist and secular liberal parties, beaten and bribed into submission, have lost credibility in most Arab countries. Only the Islamic parties have not been co-opted.
There are as many flavours of Islamic politics as there are of icecream. Some are retrograde and hostile to all opinions other than their own; others are as open and reasonable as the "Christian Democratic" parties of Europe.
The most important thing that non-Arabs can do, especially in the West, is not to panic. Knee-jerk assumptions that such regimes would be implacably hostile to non-Muslims would operate as self-fulfilling prophecies, but it ain't necessarily so.
Gwynne Dyer is an independent journalist based in London.