In the Middle Ages, books were so valuable that monks would often inscribe curses against people who would steal or damage them. Not a bad idea, really. Here’s a great example:
This book belongs to S. Maximin at his monastery of Micy, which abbat Peter caused to be written, and with his own labour corrected and punctuated, and on Holy Thursday dedicated to God and S. Maximin on the altar of S. Stephen, with this imprecation that he who should take it away from thence by what device soever, with the intention of not restoring it, should incur damnation with the traitor Judas, with Annas, Caiaphas, and Pilate. Amen.
Or this one:
May whoever destroys this title, or by gift or sale or loan or exchange or theft or by any other device knowingly alienates this book from the aforesaid Christ Church, incur in this life the malediction of Jesus Christ and of the most glorious Virgin His Mother, and of Blessed Thomas, Martyr. Should however it please Christ, who is patron of Christ Church, may his soul be saved in the Day of Judgment.
In 1212, it was decreed that curses inscribed in books were not valid, and monks were forbidden from the practice, since “to lend is enumerated among the principal works of mercy”.
Text Hexes [Futility Closet]