That’s the official flag of Oca (Goose), one of the 17 contrade of Siena, which date to the Middle Ages. It turns out that St. Catherine of Siena was born in the 14th century within the boundaries of Oca. Her body is in Rome, but her head is preserved in the Dominican church here, and can be seen inside a reliquary. She is not only one of the Catholic patron saints of Italy and Europe, but also, naturally, the patron saint of Oca.

The story goes that when she was named by the Pope in 1970 as one of the “Doctors of the Church” — a very rare honor — Siena celebrated by declaring an extra Palio. As fortune would have it, Oca drew the best horse of the lot that year, and paid handsomely to hire the best jockey. St. Catherine’s triumph would be Oca’s triumph.

But Oca did not win.

Shocked and appalled, the priest who served as Oca’s chaplain is said to have gone into the church of San Domenico, where the saint’s head is exhibited, turned out all the lights around her, and spat, “You whore! If you cannot give a victory to your people, you deserve to sleep in the dark!”

They take their contrade very, very seriously in Siena. Here, there’s a saying: “Va bene, presto c’e la terra in piazza.” It means, “Everything’s fine, soon the dirt will be in the piazza.” That is, no matter how bad your life is going, before long, they will put dirt in the massive public square at the heart of the city, so the horses can run the Palio. The idea is that the Palio is a communal rite of exaltation and absolution, the day on which all is well.

At lunch today, my traveling companion Sordello, a New Orleanian, said the contrade are like tribes of Mardi Gras Indians. If you saw the HBO series Treme, you’ll remember how the Big Chief lost nearly everything in Katrina, but as long as he had his tribe, and Carnival, all was well.

That.