What are the motifs in The Discarded Image: An Introduction to Medieval and Renaissance Literature by C. S. Lewis?

Medieval Bookishness is a recurring idea in the story. While some of the beliefs of the Medievals may seem primitive or crude by modern standards, they should be carefully distinguished from the beliefs of other, "barbaric" societies. For most civilizations, beliefs are almost a spontaneous reaction to one's surroundings, a kind of rationalized instinct. The Medievals, however, were too scholarly for this approach; they had instead an obsession, perhaps excessive, with the authority of books.