Stained Glass Roundel with an Angel Holding a Scroll (1425–1450) - Public Domain Catholic Painting

The term pot-metal refers to glass that received its color in the melting pot when various metallic oxides were added. It was then possible to paint the surface of the glass in order to outline, decorate, and define details such as eyes and hair--as may be observed on this stained glass panel.

Angels: According to Catholic teachings, angels are spiritual beings intermediate between God and humans^[1]. Three angels are named in the Bible: Sts. Michael, Raphael, and Gabriel, who are known as archangels^[2]. Catholics believe that guardian angels exist to protect and guide them^[3]. The Catholic Church also teaches that angels are sent by God to carry out his will and act as messengers of divine revelation^[1].

Evidence of stained glass dates back to the Ancient Roman Empire, when craftsman began using colored glass to produce decorative wares^[1]. The oldest complete stained glass windows were those of Augsburg Cathedral in Germany, constructed in the late 11th century^[2]. In early Christian churches of the 4th and 5th centuries, there are many remaining windows^[3], and many histories of stained glass begin with Pliny's tale of the accidental discovery of glass by Phoenician sailors^[4]. Stained-glass windows have been admired for their utility and beauty since ancient Rome, when pieces of colored glass were assembled into patterned window designs^[5].