Scala/Art Resource

A semicircular mosaic in the Church of San Vitale in Ravenna, Italy, depicts two events in Abraham’s life when God intervenes. On the right, Abraham turns away from his son Isaac as he hears the call of the angel of the Lord. With upraised sword Abraham looks up at the divine hand reaching from heaven to stay the impending sacrifice of Isaac. A small ram stands to Abraham’s left, soon to replace Isaac upon the altar.

The remainder of the mosaic, to the left of Abraham and Isaac, represents events recounted in Genesis 18:1–12. The Lord and two angels, in the guise of three men, visited Abraham at his tent by an oak at Mamre, near Hebron. Abraham roused his wife Sarah to bake three cakes. He himself selected a calf from the herd and had it prepared. In the scene shown here, Abraham offers the calf on a platter to the three wayfarers, who are seated at the table set with three cakes. The men ask Abraham where Sarah is, and Abraham replies that she is in the tent. She is in fact listening at the entrance to the tent. She overhears the Lord say that he will return at the appointed time and that Sarah shall then give birth to a son. Sarah smiles—in happiness or disbelief—because she is a woman of 90 and childless.

The Church of San Vitale, built between 526 and 547 A.D., was the most important church in Ravenna when the town served as a stronghold of Byzantine rule under the Emperor Justinian.