28 and 6

Street to the Synagogue  in Siena

We wended our way through back streets today to make it to our classroom. The Campo is blocked off as they are preparing the dirt race track for the palio.  The trial races (there are three to select the 10 horses that will run on Saturday) are tomorrow morning and you can feel the excitement building.

The detour took us through the area where the synagogue is and has been for several hundred years. As in most of Europe, the Jewish population in Siena contributed immensely to the civic and physical construction of the city...and also suffered greatly. In 1348, just after Dante's time, the plague took a heavy toll on Siena's population and the Jews were blamed for this and exiled to the outskirts of the city.

A plaque on the outside of the synagogue described the events in 1799-on this very day (June 28th). After the French revolution, Napoleon lifted many restrictions on the Jews. A revolutionary anti-semetic group called Viva Maria protested and stormed through many towns in Italy wreaking havoc on Jewish neighborhoods and people. 19 Jews in Siena were killed in the horrible uprising and a fast every year on this date commemorates the suffering. Rebecca Weiner has an excellent blog with a virtual tour of Jewish landmarks in the city and a brief history here Siena's Jewish History

Frankly, I think I would not have registered the date on the plaque had we not just had an excellent lecture by  mathematician Gary Towsley. His lecture touched on some of Dante's mathematical knowledge and its use in the poem. This is the first time I have understood anything of those intricate drawings of intersected circles in many translations of the Commedia and it was so exciting. I won't begin to explain the Aristotelian notion of Earth and its relationship to the planets and stars surrounding it, but I do want to include some information about perfect numbers.

But before I get to that, let me say a word about one of the Cantos we studied today, Canto 3. Canto 3 of Inferno introduces for the first time the idea of the punishments in hell matching the sin. Contrapasso is the Italian word for it-I can think of several people for whom I really wish I had some contrapasso!

 The other is the idea of only getting as much as you are ready for. As readers we are also subject to this latter idea-we are only shown or told as much as we are ready to understand by Dante the poet as we travel with him

I have had people say this to me several times before as I was reading the Commedia  but today was the first time I felt it physically. Proof of this is that I actually understood the explanation of how the classics used math-and how mathematicians in Dante's day used it to describe the physical world. (Though it still baffles me that they spent such time and energy trying to work out how to mathematically describe the movements of the planets based on a stationary and central Earth).

In Dante's day, mathematicians described several numbers that were perfect-that is those for whom the sum of the number's proper  factors (those not including itself) was equal to the number itself. The first is 6 (1+2 +3), the second 28 (1+2+4+7+8), the next 496 then 8,128 and so on They are a big deal both because there are not a whole lot of them (I think there are now 47 known), and because they embody perfection-the parts and the whole are equal.

Dante's poem has six perfect numbers in it (Cantos 6 and 28 in each of the three books), and these Cantos themselves have important things to say about perfection or the extreme lack thereof. Check them out for yourselves

My perfection has been this day-6 and 28! Learning so many new things, feeling history through the soles of my feet, running alone at sunrise on top of Medici Fortress, and again with four of my fascinating fellow Seminarians at sunset, and now sitting down to a glass of Chianti and two more Cantos to read.