I don't know what took me so long, but I've finally read A Canticle for Leibowitz, and it is one of the best, most engrossing, most moving books I've read in a long time. The book is divided into three parts, each a window into a post-apocalyptic society as humans struggle to regain what they have lost. Miller only gives us a few characters and a smattering of details about what happened, but it is a testament to his skill that he is able to evoke so much with so little.
Shortly after a nuclear war devastated the planet, the surviving humans have turned their rage not just on the leaders responsible, but on any literate person. Leibowitz is a former scientist who converts to Catholicism and founds an order of monks -- "bookleggers" -- dedicated to preserving any scrap of scientific learning they can. In the first section, 600 years later, the abbey is still keeping "Memorabilia" safe and hidden from the violent, willfully illiterate tribes around them. As the novel opens, a novice out on a Lenten fast stumbles upon a fallout shelter linked to Leibowitz, something that has major repercussions not just on their mission but on the canonization of their founder. This section has obvious parallels to the so-called Dark Ages, after the fall of Rome, when Catholic monasteries copied and recopied not just religious texts, but Greek, Roman, and Arabic works, in an effort to preserve their contents. It is from this tradition that our university and educational system sprang.
The next section is the weakest, but still worthy in its own right. 600 years later, humans are on the verge of another Renaissance, and a secular scholar from the city-state of Texarkana travels to the abbey to examine the Memorabilia. Many people have described this section as a battle between faith and science, but that's not what's going on at all. The monks, after all, have spent over 1200 years preserving what scientific knowledge they could, and it is a monk who is the one to rediscover electricity, much to the scholar's chagrin. Instead, the point is that faith cannot be divorced from scientific progress. Humans should not let their pride and curiosity outstrip their morality; just because you can do something doesn't mean you should.
The final section is the most moving. Another 600 years have passed and humans are once again on the brink of nuclear war, having learned nothing from their own history. All this has happened before, and all this will happen again. Eden, Rome, America, Texarkana; the nuclear fallout is another Fall of Man. And once again, a handful of monks are tasked with preserving whatever they can of faith, hope, and humanity. It is tragic and profound and beautiful. Go read it now.