The full title is "THE PRINCIPIA DISCORDIA or, How I Found the Goddess and What I Did To Her When I Found Her, THE MAGNUM OPIATE OF MALACLYPSE THE YOUNGER, Wherein Is Explained Absolutely Everything Worth Knowing About Absolutely Anything".
The Principia could just be a joke, or series of jokes, but has value beyond making the reader laugh. Among other things, it reminds people not to take themselves too seriously.
External links
Principia Discordia is available online at many locations including: