A Canticle for Leibowitz is an excellent book that showcases one of any number of post-apocalyptic possibilities. It shows how future generations might mistake our own instruments, language, and methods of living. It also shows how future generations might look upon our way of life and how they might praise or scorn it. The book also goes into satirical detail about what could happen if the world were to go into another period of ignorant religion without reasoning and scientific inquiry - apocalypse or not.
There is a bit of a good note, however. It shows how our present society's mistakes can always be repeated and should be showcased to future generations as to what not to do. The whole book can be taken as both a satire and lesson for its readers.