“I promise, I promise. I’ll return it as soon as I’m finished.”
How many times have you heard that just before you reluctantly loaned a friend a book? You just know that you will never see that book again.
Well, here is the answer. It’s an ancient mediaeval curse you can paste into the front of your books.

The trouble is — it is a fake.
On the website: www.timeshighereducation.com Colin Higgins has this to say in part about the curse.
“It is an amusing hoax dating from 1909. Edmund Pearson, joker, librarian and true-crime writer, claimed it was part of a rediscovered Old Librarian’s Almanack originally published in 1773.”
That’s not to say that there aren’t mediaeval book curses, and quite powerful ones at that, just that this beauty is not authentic.
Here is one from the year 1172 to guard a bible, followed by the original latin.
If anyone take away this book, let him die the death; let him be fried in a pan; let the falling sickness and fever seize him; let him be broken on the wheel, and hanged. Amen.