Photo by Cameraphoto/Art Resource, N.Y.

ON THE COVER: From the Creation to the Curse of Cain, scenes from Genesis enliven this 13th-century mosaic dome in the Church of San Marco in Venice. The outer circle is devoted to the Fall of Adam and Eve; throughout the inner two, winged figures in white robes represent the days of creation. One winged figure attends as God separates the red orb of light from a grey globe of darkness on the first day of creation (inner tier, above center), and, on the final day, six figures watch as God enthroned blesses the seventh day, also a white-robed figure (second tier, lower left).

Modeled on illuminations from a fifth-century C.E. Greek manuscript of Genesis, the San Marco mosaics illustrate how early Christians used symbolic figures to represent the days of the week. In “7 vs. 8: The Battle Over the Holy Day at Dura-Europos,” Stephen Goranson examines how Jews and Christians used biblical illustrations—including personifications of the days of the week—as weapons in a battle over the appropriate day of worship.