A post-apocalyptic novel, A Canticle for Leibowitz is much different from most works in the genre. It is an expansive work which spans a period of centuries, while giving us brief snapshots of what life would be like after humans almost annihilated themselves somewhere in the late 20th Century.
For some reason which is not specified in the book but is quite easy to guess, humanity is almost wiped out in an event what has been called “The Flame Deluge”, a clear indication of a cataclysmic nuclear event. This is followed by the destruction of all written knowledge and the onset of the dark ages.
Through all this, the lamp of knowledge is kept barely alight by an order of monks in an abbey in the middle of nowhere. They revere Leibowitz, an engineer who managed to save some technical documents from the deluge. Now, its the mission of these monks to accumulate and preserve whatever knowledge could be salvaged, in the hopes that someday, humanity will again be able to understand the forgotten knowledge.
Its a story of this noble pursuit which plays itself out through the ages, from a feudal society to a spacefaring one. There are strong biblical references throughout the book, which don’t seem out of place. The Church has been portrayed as the preserver of knowledge, which is admittedly a far cry from the Catholic Church in the medieval ages.
While the tenor of the book is one of hope, the end chooses to attribute greater significance to the destructive tendencies of our race. After millennia, humanity again makes the same mistakes and pushes the planet to the brink of destruction, having learnt nothing from (or indeed, forgotten) the last time it happened. The story ends with a handful of survivors setting off into deep space, to keep humanity alive, albeit in a faraway and strange planet.