In the early Christian period, mosaics became the prestige medium for the decoration of church walls. Mosaicists adapted motifs from the world of Roman art, including floor mosaics, to create narrative and “iconic” scenes to educate and remind viewers of important biblical episodes, or to serve as devotional aides. Compositions starring key figures in the heavenly hierarchy, especially Christ and the Virgin Mary, developed differently across the Mediterranean: in the west, schemes featuring Christ as savior or teacher were prominent, while in the east images of His miraculous appearances (“theophanies”) were more common. Inscriptions encouraged praise of sacred figures and donors, while written descriptions (ekphraseis) emphasize the wonder that mosaics were intended to evoke in viewers. Close study of mosaic materials and production reveals the existence of long-distance trade networks that transported glass between east and west, as well as the possibility of both local and itinerant workshops.