The medieval stained glass window was composed of colored glass, and the pieces were joined together with lead. When sunlight penetrates the window during the day, a person inside the building sees intense colors, like precious stones. Since stained glass windows were normally placed very high in a church, a person could not distinguish the scene or the people who were represented, but he or she knew from the priests that they existed. The window was therefore a metaphor for religious faith, in which one believes without being able to see it. And the artist worked for the eyes of God, not for mankind.