Or maybe it is the Sicilian quiet of the place, strung along a mountainside, ringed by stony peaks. Or perhaps the occasional military vehicle that rumbles through its few streets, automatic rifles pointing out in all directions.
A son of this little town recently broke a sacred oath. When he was a young man they pricked his finger and drew his blood. They set fire to a picture of the Virgin Mary and told him to clasp his hands and repeat the words after them: 'May my flesh burn like this holy paper if I should betray.'
Now Baldassare di Maggio, 39, the son of a shepherd, has betrayed. Arrested on a minor charge in the north, Baldassare called in the head of the carabinieri and, demanding a large sum of money, told him what the authorities have wanted to know for nearly 24 years: how to capture Salvatore Riina, capo di tutti capi, boss of all the bosses, Godfather of all Mafia Godfathers, the 'wild animal', a man charged with scores of murders.
Listen, he told them, there is this area on the edge of Palermo where he hides; there is this road, the Avenue of the Sicilian Region; there is this traffic bottleneck: there, in the morning, you can get him. He had been Riina's driver and he knew. On 15 January, that is exactly what the carabinieri did.
Di Maggio is relatively safe in a northern jail. But his home town is gripped by fear. His immediate family are said to have fled. Others, perhaps old ones or more distant relatives, have stayed, terrified of the revenge that, for centuries in Sicily, has followed betrayal as night follows day.
The age-old silence of Sicily has fallen on the place. 'I'm not from here,' people mutter, if they answer you at all. 'Some know them, some don't,' grunts a man delivering heating oil at the house next to their home. 'People mind their own business here,' his mate warns, shaking slightly. Even the chief of the carabinieri, an arrogant Neapolitan, will say nothing, except that he is 'not Sicilian, nor would I ever want to be'.
Where the di Maggios live is obvious enough: since Riina's arrest last Friday five soldiers from the Aosta regiment on anti-Mafia duty in western Sicily, wearing shrapnel-proof jackets, guard the access to their home, an unfinished concrete construction overlooking the main street. Others patrol the dirt tracks that pass for side streets, and search cars for weapons. Then periodically they all pile into their vehicles and drive off, leaving the building totally unprotected.
Revenge, if and when it strikes, could come from Corleone, half an hour to the south-east along the winding mountain roads. Corleone is the Mafia stronghold. Its bosses of the past half-century were all born there: Dr Michele Navarra, cultured chief of the old rural Mafia; Luciano Liggio, the savage killer who shot 76 bullets into him, and took the Mafia into urban construction rackets; and the even more savage Riina, who turned it into today's drugs- and arms-running multinational.
Riina's Corleonesi clan is the toughest of all, and it dominates the Mafia. Riina's two lieutenants, Bernardo Provenzano and Leonardo Bagarella, both in hiding, are from Corleone, too. On one of these gentlemen, Riina's mantle may now have fallen.
In an old, yellow corner house among the steep cobbled streets of Corleone, Antonietta, Riina's wife (who is also Leonardo Bagarella's sister) has taken refuge with her relatives since her husband's arrest. She and her four teenage children are rarely seen. 'Go away]' a woman's voice screeches through the intercom to the stranger who rings the bell.
Some predict that, with Riina out of the way, war will break out among the clans and the pax mafiosa, which has reigned in Corleone since the last internecine murder 15 years ago, will give way again to slaughter. 'It could happen,' says Captain Francesco Iacono, courteous, sophisticated and clearly ambitious commander of the carabinieri in the town. 'We are waiting to see what happens. It depends whether Riina has lost power or whether he will remain the head of the Mafia from prison. Usually when a boss is ready to go or realises he may be arrested, he designates a successor. We don't know if he has picked a successor.' He, and other Mafia-watchers, say it is highly significant that he was arrested quietly, rather than gunned down by a rival clan.
Meanwhile, the town is a haven of peace and tranquillity - the Mafia keeps order in its own house. 'There is virtually no petty crime, no drugs and no big-time crime here either,' Captain Iacono says. 'It gives us time to concentrate on finding the latitanti (the wanted men).'
They got four last week, but the coup went unnoticed because of Riina's arrest. Local newspaper accounts of the event and a cable of congratulations from on high are displayed in the hall. But the real prizes would be Provenzano (though some believe he is dead) and Bagarella. There is none of the tension in Corleone that grips San Giuseppe. There are plenty of Mafia suspects. There are still the old people who will say, 'Riina, never heard of him,' or 'I'm not from here.' But the place has changed a lot since scenes of the film The Godfather were shot here. Donkeys and stray goats have given way to cars and parking problems. Television, education and travel have done their work.
Calogero, Giuseppe and Pietro, hanging out in the main square with other lads in their twenties, say they are different from their parents. 'Our parents are backward,' says Giuseppe. 'People here are sick of the Mafia,' says Calogero. They don't like it when they travel, and people start with horror when they say they come from Corleone.
They took part in a torchlight procession recently to protest against the Mafia. When news of Riina's arrest reached the town, children cheered and applauded in the schools, people waved and gave the thumbs-up sign to the carabinieri patrols as they passed.
The Corleonesi are not afraid of trouble. 'I think Toto Riina had himself arrested,' says Luigi, the barber in the old town square. Contorted Sicilian thinking? Maybe, but that is the way the Mafia thinks, too.
Father Ennio Pintacuda, a Jesuit sociologist and Mafia expert in Palermo, also believes Riina let himself be caught. Father Ennio, who comes from Prizzi, near Corleone, is a moving force - with Leoluca Orlando, former mayor of Palermo (also born in Corleone) - in La Rete, the rapidly growing anti-Mafia and political reform movement. In prison one is still alive, he says, and relatively safe from assassination.
Riina's arrest, he believes, marks the closing of an era for the Mafia. The political protection and complicity that enabled it to build up its colossal world-wide drugs and arms trade and money- recycling empire from Sicily is dissolving as Italy's post-war political system collapses. These activities will doubtless continue, but the Mafia is now moving into Eastern Europe and the former Soviet Union, where societies are virtually defenceless against it and colossal fortunes are to be made.
'The Mafia never stands still to be photographed,' the parliamentary anti-Mafia commission once said. The blurred picture which has developed from the evidence of pentiti, or supergrasses, of the Mafia's leaders, structure and methods is already outdated, Father Ennio believes. 'There will be a new style of business, of management, much more international, less tightly centralised here in Sicily.' Who will head it is not certain. The mafiosi of the future may still be commanded by a Sicilian; but he might as easily be Turkish, Polish or Russian.