It is not a general introduction to medieval and Renaissance literature, as the subtitle might suggest, but rather a survey of its philosophical and intellectual background, a description of that synthesis of Christian and classical ideas which Lewis calls the "Medieval Model". He begins by examining some of the sources which contributed towards this model, most of which are now little known: from the classical period Cicero's Somnium Scipionis, Lucan, Statius, and Apuleius' De Deo Socratis; from late antiquity Chalcidius, Macrobius, Pseudo-Dionysius and Boethius. Lewis then describes the medieval universe, from the trans-Lunar heavens to the Earth, and its inhabitants — the "angels" in the heavens, the ambiguously located "longaevi" (of whom a faint echo survives in the modern "fairies"), the animals and man, with his different Souls, Spirits and Humours. The medieval conception of history and education is briefly touched on. The final chapter considers the influence of the Model, and the epilogue its epistemological status vis a vis the "modern Model".
The Discarded Image is erudite, eloquent and urbane. It is a very broad overview, with the simplification which that entails, but I came away from it feeling I had a better understanding of medieval literature.