Lots to ponder in this architectural-historical-geometrical-theological consideration of the great cathedral of Chartres. There are many mysteries to be considered and often no clear answers, but there is an interesting case to be made for the influence of Islam on Gothic architecture. The author sometimes lost me with his geometrical square root calculations, but made a fascinating point about the rectangular crossing of the cathedral representing the self-denial of God (backed up by theological quotes), which gave the saying "deny yourself, take up your cross and follow me" a whole new meaning for me.