Traditio Clavium (the Giving of the Keys)
Christ giving the Keys of the Kingdom of Heaven to S. Peter is in Matt. 16: 13–20, the actual words of the donation being in v. 19. Jesus asked the disciples ‘“Who do people say that the Son of Man is?” And they said “Some say John the Baptist, but others Elijah, and still others Jeremiah or one of the prophets.” He said to them, “But who do you say that I am?” Simon Peter answered, “You are the Messiah, the Son of the living God.” And Jesus answered him, “Blessed are you, Simon son of Jonah! For flesh and blood has not revealed this to you, but my Father in heaven. And I tell you, you are Peter, and on this rock I will build my church, and the gates of Hades will not prevail against it. I will give you the keys of the kingdom of heaven, and whatever you bind on earth will be bound in heaven, and whatever you loose on earth will be loosed in heaven.” And he sternly ordered the disciples not to tell anyone that he was the Messiah.’
The curious answer that some believed Him to be John the Baptist, whom Herod had already killed, is because of a belief in the reincarnation of prophets. It also explains the references to Elijah and Jeremiah, particularly since Elijah, who had been taken up to heaven alive, was expected to return to earth as a presage of the restoration of Israel and its deliverance from its foes. Jeremiah, who is believed to have been stoned to death by Jews enraged by his repeated calls to repentance, predicted the fall and destruction of Jerusalem and wept over the city he loved, but knew was doomed. He is seen now as an OT prefiguration of Christ, and the Roman conquest of Palestine would have predisposed thoughtful Jews of that time to equate Jesus, as a new and very powerful prophet, with one of the great prophets of antiquity. The subject appears in Early Christian art mainly in sarcophagi, and in the mosaic semi-domes of some of the early churches in Rome. The sarcophagus of Junius Bassus (359: St Peter's Mus.) is one of the earliest, and shows Christ, seated over Coelus, a personification of the Heavens, giving a scroll both to S. Peter and S. Paul. The sarcophagus of Probus (395: Grotto of St Peter's) shows Christ holding a jewelled cross, and with a scroll in His hand, standing between SS Peter and Paul. The dome of the Arian Baptistery, Ravenna, c.500, has a mosaic of the Throne of God with S. Peter one side holding keys, and S. Paul the other side, holding a scroll. A miniature in the Golden Evangeliary of Henry II (1002–14: Munich) shows Christ handing an object, presumably keys, to S. Peter with the other disciples standing behind him. In a miniature in the Sermons of S. Anselm of Canterbury (1130: Verdun) Christ, with sheep at His feet, hands two large keys to S. Peter. A relief by Donatello (1428–30: London, V & A) shows Christ giving the keys to S. Peter at His Ascension. The Sistine Chapel has—or had—two important representations of the donation: the Perugino in the fresco series of 1481 has Christ giving the keys to S. Peter kneeling before Him, and the Raphael tapestry of 1515/16, now in the museum, but made for the Chapel, combines the scene on the seashore of ‘Feed my Sheep’ with S. Peter kneeling before Him holding the keys in his hand. These two images, in the Chapel which was the place where conclaves for the papal elections were held, were powerful visual assertions of the Petrine Primacy, and reminders of Christ's words, ‘… and upon this rock I will build my Church’.