‘Send out your light and your truth; they will lead me’, the psalmist prays (Psalm 43:3 own translation). In stone, glass, and gold, this mosaic seems also to achieve a ‘sending out’, disclosing the distinctive beauty of each of God’s creatures.

Ancient Christian legend maintained that the cross erected on Golgotha stood in the very same spot on earth where God had once planted the tree of life. The Apse Mosaic develops the full theological potential of that legend.

On either side of the cross the acanthus plant, watered by the streams of Paradise, extends its tendrils. ‘We liken the church of Christ to this vine’, begins the Latin inscription at the bottom of the apse. Fifty spiralling vines fill the entire space, even dwarfing the cross. The number fifty recalls the church receiving the Spirit on Pentecost, fifty days after Passover and the Resurrection, and further the Jubilee, the fiftieth year, a year of liberation for the oppressed that Jesus proclaimed (Luke 4:18–19). Each of the tendrils bursts into flower or fruit at its tip; this is the ever-bearing tree of Paradise (Revelation 22:2). Growing around the cross, it reveals Golgotha as the site where God’s creative and redemptive work culminates.

In a visual summary of the created order, the full spectrum of the medieval Christian world is shown nestled among the vines, with all of its members pursuing characteristic activities. Here are countless birds and winged cherubs, princes and nobles, eminent theologians with book and pen in hand, tonsured monks in the kitchen, a woman feeding chickens, women and men tending sheep and goats, a family in conversation, youths gesturing into space. The effect of variety is enhanced by the mosaicists’ technique—a medieval innovation—of working on a rough mortar surface, so the slightly uneven plane of tesserae catches light at different angles.

‘Send out your light and your truth…’ Perhaps the artists who produced this work of almost unrivalled luminosity found in that prayer a reflection of their own vocation.

References

Poeschke, Joachim. 2010. Italian Mosaics, 300–1300, trans. by Russell Stockman (New York: Abbeville Press Publishers)

Sundell, Michael G. 2007. Mosaics in the Eternal City (Tempe: Arizona Center for Medieval and Renaissance Studies)