Chartres cathedral is a marvel but also a mystery. Nobody knows who designed it or what they were trying to express. Begun in 1200 and finished in 1226, it was the crowning example of the gothic style and marked, Philip Ball suggests in this lucid and resplendent book, a shift in the way the western world thought about God, the universe and man’s place in it. Romanesque churches with their vast walls and narrow windows had been dark and inward-looking, and signified, he argues, monastic seclusion. Chartres changed all that. Its walls were diaphanous membranes of glass set in cobwebs of stone. On the outside, flying buttresses propped them up to prevent them collapsing under the soaring vaults of the roof. It was “transparent logic”, a celebration of the light of reason, banishing the old gloom, and progressing from an age when God was feared to one where his works could be understood.

That, at any rate, is the theory.

more from the Times Online here.