Light in European culture has always been seen as sublime in religious and metaphysical terms. The biblical story of Genesis even starts with the creation of light. At the same time light has always been understood as the precondition of knowledge, not least in the era of the Enlightenment, being the central metaphor for spiritual illumination through reason. And thus illuminated stained glass windows have been regarded since the early Middle Ages as a suitable medium for expressing these perceptions in material and artistic form, capable of combining architectural requirements with spiritual content in cathedrals, churches, synagogues,