The real mystery is that for so many centuries the four societies of Prague - Czechs, Germans, Jews and Italians - lived and worked together, or at least side by side: the Czech baker and candlestick-maker, the German civil servant, the Jewish merchant, and the Italian craftsman of the building trades, as well as their wives, sons and daughters.
There were many decades of tolerance, peace and prosperity but then there were the years of mass murder and expulsions. Three thousand Jews were killed in 1389, the Austrian Empress Maria Theresa expelled all Jews from the ancient town, and between 1940 and 1944, the years of the Shoah, the transports rolled to the camps.
At the height of the Hussite revolution (1420), the Catholics of whatever language had to leave, and after the Battle on the White Mountain, 200 years later, it was the Protestants who had to convert or leave; after the the Second World War, almost all Germans were expelled.
In the Democratic Republic of the 1920s and 1930s, citizens of all creeds and languages were protected by the constitution and the laws. When you felt Czech you read the patriotic newspapers, went to see the new play at the National Theatre, frequented the Cafi "Salvia', and on Sunday went with your kids to the Vysehrad where the great men and women of the Czech nation were buried.
If you were German or a German-speaking member of the Jewish community, you had your own set of newspapers, attended the German Opera House, had your coffee at the "Louvre', and took your kids on Sunday to the "Baumgarten" (stromovka, in Czech).
If you felt not particularly bound to either nation and spoke both languages it was all the better because you could talk to all the girls and take them to the movies, preferably those on fashionable Wenceslav Square
Now the city has changed and yet it has not; the bridges, palaces and chestnut trees are all there but the vulnerable interchange of idioms and the lively rituals of the different societies have gone, as irretrievably as those of ancient Alexandria or modern Sarajevo. That colourful magic of the many societies living in one place for centuries will not be easily restored, and the cosmopolitan din of the tourists does not, I think, entirely compensate for the loss.
I was first terribly mad at the purveyors of magical commodities, and later I was sad to learn that even my Czech friends for many decades cut off from public habits of sober analysis, were prone to accept a mythical image of their city - not because they were mystics (the writer Bohumil Hrabal reminds us that the favourite Czech Sunday meal consists of pork, cabbage, and dumplings) but because the Communists had favoured an official cult of the "real" and "realism": and to hold up magic traditions was a clear move to oppose the views prescribed by government.
Peter Demetz is the author of 'Prague in Black and Gold' (Penguin, pounds 9.99)