The Eagle identifies the six souls that form the eye and brow of the great bird: David is the pupil — the singer who moved the Ark, who suffered for his sin, whose repentance created the Psalms. The brow: Trajan, Hezekiah, Constantine, William II of Sicily, and Ripheus the Trojan. David and William are perhaps expected. Trajan is surprising. Ripheus is extraordinary — he is a character from Virgil's Aeneid, barely mentioned, praised by Virgil as the most just of all the Trojans, who died in the fall of Troy. He is entirely fictional in the historical sense; he never existed. Yet here he is in Heaven.
The Eagle, reading Dante's amazement, explains. Trajan, the pagan emperor, was restored to life by Pope Gregory the Great's prayers — brought back briefly so that he could hear the Gospel and convert before a second death. Whether this is literal or symbolic, it represents the conviction that grace can operate outside normal channels when God wills it. As for Ripheus: his natural moral sensitivity was so acute that, centuries before the Incarnation, he received through a kind of anticipatory grace — faith in the Christ to come — the three virtues of Hope, Faith, and Charity, administered to him by the divine goodness he already loved. He was baptized in spirit before baptism existed. The lesson: "The predestination of God, how far removed its root is from those faces that see not the whole of the First Cause!" Human theology cannot map where grace goes. Both souls sit in the Eagle's eye, which is the eye of justice — because in them, justice and mercy coincide perfectly.