Peter gazes knowingly across the millennia in this fifth-century mosaic from the Church of Saint Paul Outside the Walls in Rome. In the Gospels, Peter appears as flawed disciple; he hesitates, doubts and even denies ever knowing Jesus. Yet, Jesus chooses him as his successor with the simple command, “Feed my sheep” (John 21:17). In the accompanying article, Pheme Perkins traces how Peter became Jesus’ earthly successor.