The thirsty deer of Psalm 42 stands at the foot of the cross in the Apse Mosaic, the crown jewel of the twelfth-century church of San Clemente in Rome. In fact, three deer constitute the foundation of the glowing composition, which offers a condensed visual account of all salvation history and the work of the three Persons of the Trinity.

At the bottom, two deer slake their thirst from the four rivers that flow from Eden (Genesis 2:10). Just above, one deer, encircled by a red serpent, drinks from a great body of water. Is this the primeval deep (Genesis 1)? Or the river of the water of life (Revelation 22:1)? The image may recall an ancient belief that deer eat venomous snakes, neutralizing their poison with copious quantities of water. Psalm 42 figured prominently in baptismal liturgies, and medieval viewers would have recognized in the scene allusions to the soul’s thirst for God’s grace and deliverance from deadly sin through the sacrament.

Above the lone deer spreads an acanthus plant. Greeks associated its thorny, aromatic leaves with victory over suffering, and Christians with resurrection; in John’s Gospel (19:2), the soldiers plait a crown of akanthos for Jesus. Here the cross rises from the plant and stretches nearly the height of the apse, to where a divine hand reaches down to crown him with a victory wreath. The cross is surrounded by thorns and studded with twelve doves, symbolizing the apostles in their innocence (Matthew 10:16).

The gold background that fills the apse represents the divine glory that fills the world through the discrete actions of the Triune God: the original creation (Eden), Jesus’s victory on the cross, and the renewal of creation through the Spirit of the crucified and risen Christ.

References

Oakeshott, Walter. 1967. The Mosaics of Rome: From the Third to the Fourteenth Centuries (London: Thames & Hudson)