A Canticle for Leibowitz by Walter Miller (1960)
After the fall of the Roman Empire, Western civlisation contracted to such an extent that its only outposts were monasteries like Iona on the outer edges of the known world. There the monks preserved what little was left of Classical learning against the day then the shattered world healed itself until ready to use that knowledge once again. A Canticle for Leibowitz tells the same story, though in Walter Miller's novel history repeats itself after a nuclear war and the civil unrest hurls the human race into a new dark age. Originally published in The Magazine of Fantasy and Science Fiction as a trilogy of novellas, Canticle follows the adventures of the brothers of the Albertian Order of St Leibowtiz; a monastery somewhere in what was once New Mexico dedicated to preserving what books could be salvaged from the holocaust and founded by Isaac Leibowitz, a 20th century Jewish electrical engineer who converted to Catholicism after the war and was hanged as a "booklegger" by a Luddite mob bent on destroying all knowledge.
Reflecting its magazine origins, the novel is split into three parts. The first follows a young novice who with the help of a mysterious old man discovers the ruins of an ancient fallout shelter containing relics of St Leibowitz, which turn out to be a shopping list and a blueprint of an electronics schematic. The second involves a visit to the monastery by a scholar wishing to study their book collection, which places the Order in the middle of a war between rival empires. And the third sees the world rising out of barbarism to a new civilisation capable of interstellar travel, yet doomed to repeat the cycle of the previous society in destroying itself by nuclear fire
A Canticle For Leibowitz is one of those books that are genuine science fiction classics, but don't sit very well with sci-fi fans. It is very much science fiction, but it doesn't deal with the usual spaceships and ray guns, nor does it gallop about in a romantic post-apocalyptic world. Science fiction compliments itself as being a genre of ideas, but those ideas tend to be very secular and even materialistic. A novel that revolves around ideas that are not only Christian, but Catholic and which treats Christian ideas with respect rather than as an adolescent punching bag is a rarity only seen at that time in the works of C S Lewis and James Blish. It's a novel where the question is posed throughout as to how one can reconcile God and Caesar and where an abbot faces a world where people believe that the only evil is pain and that society is the only thing that determines whether an act is wrong or not and he reacts with justifiable horror at such moral husks.
This is not, however, a dry polemic or apologia. This is a story of wry humour and of imperfect men struggling with faith in a very imperfect, even brutal, world. Many chapters are flat-out funny while others have a poignancy such as a story where one of the main characters is Lazarus, raised from the dead by Christ 3500 years ago and commanded to wait for His return. Many modern readers may be put off entirely by the subject matter or that lack of melodrama, but if that causes them to pass over Canticle, then the loss is theirs.