"A Canticle for Leibowitz" is a science fiction novel by Walter M. Miller Jr. set in a post-apocalyptic future where civilization has collapsed after a nuclear war. The story follows the monks of the Albertian Order of Leibowitz, who preserve the remnants of human knowledge and culture, particularly the works of the 20th-century scientist Isaac Leibowitz. The narrative spans centuries, exploring themes of faith, knowledge, and the cyclical nature of history. As society rebuilds, the monks face challenges from both external forces and internal conflicts, highlighting the tension between science and religion in a world struggling to learn from its past mistakes.