"The Zen Librarian said to a patron: 'If you bring back this book after its due date, you will be fined. If you do not bring back the book after its due date, you will be fined.' The patron was instantly enlightened." - "The Zen Librarian searched for nothing on AltaVista and received 27,987,384 hits". This and more on "Koans of the Zen Librarian" from "The laughing librarian".