Stars in their Eyes

There were three really interesting things that I could have gone to see last night - the Walking Festival talks at the Swan, a folk singer at the Globe, and a talk about medieval astronomy at Cusop Church.
I chose the medieval astronomy, because I went to the talk that the speaker, Martin Griffiths, did last year, and thought it was absolutely fascinating.
This time the church wasn't quite so full, but the weather had been pretty awful, which may have dissuaded people from going out.
The talk centred around the state of knowledge in the medieval period in Europe, where a lot of the knowledge of the Classical World had been lost - or rather, it had moved East, to the Islamic world, Vedic India and China, where they encouraged the love of knowledge for its own sake. In the Medieval Christian West, theology was the Queen of Sciences and anything else wasn't seen as important.
The situation was complicated, though, because on the one hand the Church was limiting knowledge to what was acceptable, and what fitted with the Bible (even if it was contradicted by actual experience), and on the other hand the Church had saved knowledge from the Classical world such as Plato and Aristotle (who was a "rubbish scientist", but whose works were copied for 1500 years).
Astronomy was important to the Church because of the difficulties of calculating the correct date for Easter every year, so that was studied - with the proviso that the Earth was, naturally, in the centre, with the planets, Moon and sun going round it.
Astrology was also important, and to cast an individual's horoscope you need to know the positions of the planets. Astrology also had a correspondence between an astrological sign and each part of the body. Chest problems which we would now call lung cancer were common in the smoky atmospheres of medieval housing, with all those open fires, and the chest was ruled by Cancer the Crab - which is where the name for the disease came from.
Another difficulty for medieval scholars was trying to do maths with Roman numerals. At this point Martin Griffiths looked around the church to find some numbers to point at with his laser pointer - Arabic numerals, except they're not really Arabic either. They originally came from Vedic India. When they had numerals which were easy to use, and one of the Popes had re-invented the abacus, they were able to do all sorts of maths problems which had been incredibly difficult before.
And then an Arab invented algebra, which made even more complex maths possible.
At around the same time, someone went down to Cordova in Islamic Spain and translated 87 books into Latin - which caused a great expansion in universities across Europe, as scholars came to grips with this flood of new knowledge. At the time, one of the biggest libraries in Europe, near Rouen, had a grand total of 39 books. Cordova had a library of half a million books.
Later in the talk, Martin Griffiths said something quite staggering while talking about Leonardo da Vinci - when Leonardo was born, it is estimated that there were only 7,500 books in the whole of Europe. During his lifetime, the printing press was invented (or rather, pinched from the Chinese, along with paper which made printing much cheaper) and when Leonardo died there were 30 million books in Europe. The Church wasn't going to be able to keep control of that outpouring of knowledge.
Back to cosmology, and Dante's Divine Comedy, which has 9 circles of Hell, Purgatory and Heaven. This was based on the Aristotelian system, and is also where the phrase "on cloud nine" comes from - the highest circle of Heaven!
So it was a fascinating evening, with a lot of questions at the end. Even better, I won a prize in the raffle (some Roses chocolates) and got a lift home!