The story of Turi Guiliano also affords Mr. Puzo the opportunity to explain the Mafia historically. He even gives us etymology. '' 'Mafia,' in Arabic, means a place of sanctuary,'' he writes, ''and the word took its place in the Sicilian language when the Saracens ruled the country in the 10th century. Throughout history, the people of Sicily were oppressed mercilessly by the Romans, the Papacy, the Normans, the French, the Germans and the Spanish. Their Governments enslaved the poor, working class, exploiting their labor, raping their women, murdering their leaders. Even the rich did not escape. The Spanish Inquisition of the Holy Catholic Church stripped them of their wealth for being heretics. And so the 'Mafia' sprang up as a secret society of avengers.''

At the same time, as if in response to those who thought he over-romanticized the Mafia in ''The Godfather,'' Mr. Puzo scourges ''the 'Friends of the Friends,' as they were called here in Sicily.'' For Turi Guiliano is not only waging war with the Carabinieri, or the Italian National Police, he is also fighting Don Croce Malo, the hugely fat Capo di Capi of the ''Friends of the Friends.''