Medieval scribes spent years upon years painstakingly copying books by hand. The thought of such work being stolen was a nightmare to them, as you can imagine. And we've seen the freedom that those scribes had, as they added personal notes and wacky art to their manuscripts. So is it any wonder that they'd also include a warning to anyone tempted to make off with their work? Quite a few of those manuscripts still exist, with warnings in the form of curses written into them, sometimes in poetic form.
2. "A WORSE END"
A 15th-century French curse featured by Marc Drogin in his book Anathema! Medieval Scribes and the History of Book Curses has a familiar "House That Jack Built"-type structure:
“Whoever steals this book
Will hang on a gallows in Paris,
And, if he isn’t hung, he’ll drown,
And, if he doesn’t drown, he’ll roast,
And, if he doesn’t roast, a worse end will befall him.”
After the printing press was developed, such curses hung on because books were still expensive (and maybe because of tradition, too). Read some of the best (or worst) curses for book thieves at Mental Floss.