It’s all very well to say that C S Lewis and the medievals valued tradition–indeed, that they hung their hopes for understanding the Truth of things on their ability to understand and act on the wisdom passed down to them. But what was the nature of that tradition? Yes, Christian, of course. But also, as we will see, Pagan.
Tradition included Pagan as well as Christian wisdom
In Discarded Image, Lewis shows us that medievals implicitly trusted historical texts as the repositories of God’s truth. He also shows that they saw truth not just in Scripture and explicitly Christian tradition, but also in the words of the Pagan philosophers and the works of Greco-Roman culture. This was true from Clement of Alexandria and Justin Martyr through Boethius, Thomas Aquinas, and Dante. Though the pagan philosophers had not known Christ in his incarnate form, they too, along with all people, had been given access to the logos – the wisdom of the second person of the Trinity.
In other words, medieval poets, jurists, moral teachers, romance writers, and theologians—all creating compendia of knowledge for their readers—were often gleefully syncretistic. Not that they didn’t care whether the deepest truth of things was to be understood in Christian, Platonic, Stoic, or Pagan terms. Christianity always provided the framework, the “norming norm,” for truth. But within that framework one might fit all the best thought of the pagans, as Christian thinkers had been doing ever since Paul spoke to the Greeks at Mars Hill about their “Unknown God,” using the words of their own poets (“In him we live and move and have our being.”)
What else would we expect from the early spread of “the Way” to the Gentiles? Who else were the Gentiles in the Roman Empire but those educated in the spiritual metaphysics of Plato, the robust moralism of the Stoics, and the epic adventures of Homer? That was the air they breathed, the water in which they swam. Naturally, they sought to understand the best in their own culture by Christian lights.
Certainly aspects of pagan teaching did not mesh with the Gospel, and these were quietly dropped. Few Christians, for example, attempted to salvage the materialism and hedonism of the Epicureans. But the philosophical quest for Truth, Goodness, and Beauty, along with the classical virtues of Prudence, Justice, Temperance, and Courage were found good. Yes, they needed to be seen in the light of the theological virtues of Faith, Hope, and Love, but that was no reason to deny their own practical wisdom. From this principled and careful “Christianization of Hellenism” came modern science. As such devout men as Roger Bacon, Albertus Magnus, and Thomas Aquinas processed the Aristotle’s natural philosophy through the Bible, they laid the foundation for science as we know it. (Modern American evangelical critics of this Greek cast to early and medieval Christian thought would do well to consider the many ways in which their own faith has become “Americanized.”)
I say all this to point out this other area of Lewis’s intuitive medievalism—A devout and public Christian, Lewis always felt more affinity for a thoroughgoing pagan pursuing virtue by Pagan lights than for a godless modern, and he returned again and again throughout his writing life to the wisdom of the ancients (as did Boethius—thus, he is Boethian in this). In a letter to Dom Bede Griffiths, Lewis showed that he had indeed absorbed this medieval esteem for the past, including the Pagan past: “[I]t is only since I have become a Christian that I have learned really to value the elements of truth in Paganism and Idealism. I wished to value  them in the old days; now I really do. Don’t suppose that I ever thought myself that certain elements of pantheism were incompatible with Christianity or with Catholicism.”
That the Narnia Chronicles may, if we believe Michael Ward, hang on an elaborate secret scaffolding of pagan planetary mythology, or that the Abolition of Man and Mere Christianity ransack Aristotelian virtue ethics and natural law theory for their ethical understanding, or that his favorite of his own novels, Till We Have Faces, was a reworked Pagan myth—Lewis saw none of this as contradicting his Christianity. Like medievals from Boethius to the Beowulf author to Dante, Lewis was a happy syncretist, at least in the typical medieval sense of “plundering the Egyptians” for usable material while maintaining a firm Christian intellectual framework (in Lewis’s words: “For one reference to Wade or Weland we meet fifty to Hector, Aeneas, Alexander, or Ceasar. For one probable relic of Celtic religion . . . a score of references to Mars and Venus and Diana”)
Lewis tells us how thoroughgoing this medieval Christian appreciation for the Catholic sources was – especially from the scholastic period onward: “From the twelfth to the seventeenth century Europe seems to have taken an unfailing delight in classical mythology. If the numbers and the gusto of pictures and poems were to be the criterion of belief, we should judge that those ages were pagan, which we know to be untrue.” Lewis had certainly been prepared by his time with Kirkpatrick to be an intuitive medievalist on this score of syncretic use of classical material.
 R. L. Wilken’s phrase—formulated against arch-liberal 19th-century historian Adolf Harnack’s accusation that the early church had engaged in a woeful “Hellenization of Christianity” that had obscured the beating heart of the faith: Jesus’ message of love.
 Lewis, letter to Dom Bede Griffiths: Rostrevor, Co. Down [4 April 1934] –Letters II, 133ff.
 Lewis, Discarded Image, 8.
 Lewis, “Is Theology Poetry?” in Weight of Glory, 76.