Emile Mâle:
In the mind of the thirteenth century a curious idea grew up. The literature of the ancient world began to seem to the scholar as in some sort a dim revelation, in which as through a veil the Christian faith from time to time was seen. The Metamorphoses of Ovid in particular, were interpreted by the symbolic method applied to the Bible, and in them the same teaching was discovered. The view so constantly put forward, that classical mythology was merely a corrupt form of biblical tradition, was scarcely that held by the scholars of the thirteenth century. In their eyes the heathen fables were of the nature of a special revelation made by God to the Gentiles, in which, as in the Old Testament, was outlined the story of the Fall and the Redemption. Among the myriad forms in Ovid's crowded tapestry Christian eyes discerned the figures of Christ and the Virgin, which as he threw his shuttle the poet had unwittingly woven in.[Religious Art in France of the 13th Century by Emile Mâle, translated by Dora Nussey. Harper & Brothers Publishers, 1958]
Nothing of the kind is more curious than a manuscript of the Metamorphoses in the Bibliotheque de l'Arsenal. Among miniatures illustrating the stories of Medea, Æsculapius or Achilles, one unexpectedly finds pictures of the Crucifixion, the Annunciation, or the Descent into Limbo, and the rhymed commentary which accompanies each story from Ovid explains and justifies the presence of the Christian subject. We learn, for example, that Æsculapius, who suffered death because he had raised the dead, is a type of Christ, and that Jupiter, changed into a bull and carrying Europa on his back, also typifies Christ, the sacrificial ox who bore the burden of the sin of the world. Theseus who forsook Ariadne for Phaedra prefigures the choice which Christ made between the Church and the Synagogue. Thetis who gave her son Achilles arms with which to triumph over Hector, is no other than the Virgin Mary who gave a body to the Son of God, or as the theologians have it, gave Him the humanity with which He must be clothed in order to conquer the enemy.
These examples will give some idea of works of this nature, in which the whole of mythology becomes prophetic and, so to say, sibylline.