The philosophy of antiquity regarded light as a divine power, an idea that continued to live in medieval theology and found its highest artistic expression in stained glass paintings. Sunbeams whose light is refracted in the windows of the cathedrals make the heavenly sphere permeate the earthly scene. Thus the other world becomes manifest on earth in a mystical way.

Gothic churches are more than just a place of worship: they are the earthly likeness of the celestial city of Jerusalem, described in the Bible as the perfection of creation. The stained glass windows symbolise the refulgent city walls that are made from precious gemstones.