“If you look at the C.V.’s of current Czech politicians, you see that most of them are in their 50s,” he said. This means they matured in what he called “early normalization,” roughly from 1969 to the mid-1970s, when the Soviet-led invasion that crushed the brief Prague Spring reforms of 1968 gave way to a dull and autocratic regime dependent on Moscow. “One of the darkest periods” of national history, Mr. Havel said.

In his view, those years have marked many current politicians, leaving them prone to conspiratorial thinking and acts of petty deceit. Compounding that, he said, is “some kind of existential crisis” caused by a global pursuit of materialism and by the specific Czech legacy of 40 years of Communist government.

Indeed, the contrast between the atmosphere in Prague today and during the magical autumn of 1989 and the Velvet Revolution could scarcely be greater. Today, the city is a freer, far wealthier place than 20 years ago, with private property restored and millions of tourists proving an economic if not aesthetic boon to one of Europe’s most beautiful capitals.

But as an exhibit at the Old Town Hall reveals, the spirit of 1989 was humane in a way rarely felt since. In grainy black-and-white photographs, the show traces the arc between the first demonstrations against Communism here in 1988, through the mass exodus of East Germans via the West German Embassy in Prague in August 1989, to the fall of the Berlin Wall and then the Velvet Revolution itself.

As Vaclav Maly, then a dissident with Mr. Havel and now auxiliary bishop of Prague, notes in the introduction to the show, “It is good to realize that once there were times when we were not afraid to show feelings, and did not take considerateness and kindness to be a sign of weakness.”

Asked for his favorite memory of the Velvet Revolution, Mr. Havel said it was the mass gathering on Letna Plain above Prague in late November 1989, when 750,000 people gathered in freezing temperatures. “It was so cold, there were too many speakers, but I looked out and felt that something was definitely changing, that it was a turning point,” he said.