There is a 1420 book that was found to have cat piss on one of its pages. The author of the manuscript even wrote on the page “Cursed be the pesty cat that urinated over this book during the night in Deventer… and beware well not to leave open books at night where cats can come.”

This medieval manuscript curses the cat who peed on it

What happens when a cat sneaks over and pees all over the precious manuscript that you’ve spent months of your life inscribing? If you’re this 15th century monk, you leave a note cursing the cat and move on with your writing.

The blog medievalfragments explains that this manuscript was inscribed by a Deventer scribe around 1420. Cats were common around medieval libraries because they hunted the vermin that saw the pages as a tasty treat. Unfortunately, where there are cats, there is also cat urine, as one scribe learned the hard way. He responded in a rather amusing fashion, drawing hands pointing toward the stain and writing:

Hic non defectus est, sed cattus minxit desuper nocte quadam. Confundatur pessimus cattus qui minxit super … Continue Reading

Source: https://io9.gizmodo.com/this-medieval-manuscript-curses-the-cat-who-peed-on-it-1502884468