A Canticle for Leibowitz by Walter M. Miller, Jr.
In this post-nuclear-war future (centuries from now), education is something despised. Along with wiping out the government officials (all of whom were blamed for the war), the mobs killed as many intelligent people as they could (who were blamed for giving the government officials the power to wage such destructive war). In the aftermath, a small community of monks strives to preserve learning. One monk is on a Lenten retreat in the wilderness and discovers a fallout shelter with an incredible amount of information in it, some of it seemingly written by the hand of the scientist Leibowitz, one of the intelligent people martyred for being smart. The community is the Albertian Order of Leibowitz, named after that man. The rediscovery of his writings is a bit like the rediscovery of Aristotle in the Middle Ages.
The intellectual revival does not happen for a long time afterward. Once civilization is built up enough, a scholar named Thon Taddeo comes to the monastery to determine the authenticity of the documents. Taddeo is secular and a bit above the religious ideas of the monks but he comes to an uneasy understanding as he discovers the monks' practical applications that dovetail nicely with his theoretical research. The intellectual renaissance ensues, bringing a new age where nuclear weapons are again available to government officials. Can mankind avoid a historical rerun?
The book is an odd blend of authentic Catholicism (including a generous amount of Latin), historical echoes (besides the Aristotle-like bit, there's a sort of Protestant Revolt), and pessimistic predictions. For a while the book seems unfocused and rambling. The ending sort of pulls things together though its blend of optimism and pessimism falls too far on the pessimism side for me to find it enjoyable. A lot of interesting ideas pop up along the way, but not enough to get a whole-hearted endorsement from me.