Enlightening programme about sacred music here (Gothic Revolution) . Here is the synopsis: "Four-part documentary series in which actor and former chorister Simon Russell Beale explores the flowering of Western sacred music. He begins his journey at Notre Dame in Paris, where an enigmatic medieval music manuscript provides the key to the early development of polyphony - music of 'many voices'. Featuring music performed by members of the award-winning choir The Sixteen, conducted by Harry Christophers".

I found that part about Pythagoras and the mathematical connection with music amazing. They explain the idea of purity in between the fourth and fifth notes. All thanks to the extraordinary BBC4 and: Open University.