For him that stealeth, or Borroweth and Returneth not this Book from its owner, let it change into a Serpent in his hands and rend him. Let him be struck with Palsy, and all his members blasted. Let him languish in Pain crying aloud for mercy, and let there be no Surcease to his Agony till he sink to Dissolution. Let Bookworms gnaw his Entrails in token of the Worm that dieth not, and when at last he goeth to his final Punishment let the flames of Hell consume him forever and aye.
Medieval Book Curse from the Monastery of San Pedro in Barcelona