2023 Reprint of an undated U.S. Edition. Full facsimile of the original edition and not reproduced with Optical Recognition Software. The Principia Discordia is the first published Discordian religious text. It was written by Greg Hill (Malaclypse the Younger) with Kerry Wendell Thornley (Lord Omar Khayyam Ravenhurst) and others. The first edition was printed allegedly using Jim Garrison's Xerox printer in 1963. The second edition was published under the title Principia Discordia or How The West Was Lost in a limited edition of five copies in 1965. The phrase Principia Discordia, reminiscent of Isaac Newton's 1687 Principia Mathematica, is presumably intended to mean Discordant Principles, or Principles of Discordance.

The Principia describes the Discordian Society and its Goddess Eris, as well as the basics of the POEE denomination of Discordianism. It features typewritten and handwritten text intermixed with clip art, stamps, and seals appropriated from other sources. While the Principia is full of literal contradictions and unusual humor, it contains several passages which propose that there is serious intent behind the work, for example a message scrawled on page 00075: "If you think the PRINCIPIA is just a ha-ha, then go read it again."

Notable symbols in the book include the Apple of Discord, the pentagon, and the "Sacred Chao", which resembles the Taijitu of Taoism, but the two principles depicted are "Hodge" and "Podge" rather than yin and yang, and they are represented by the apple and the pentagon, and not by dots. Saints identified include Emperor Norton, Yossarian, Don Quixote, and Bokonon. The Principia also introduces the mysterious word "fnord", later popularized in The Illuminatus!