Some monks apparently added lighthearted touches to the marginalia of their manuscripts by doodling murderous beasts, penis monsters, and assorted bizarre and vulgar images.

The Decretum Gratiani, also known as the Concordia discordantium canonum or Concordantia discordantium canonum, is a collection of Canon law compiled and written in the 12th century as a legal textbook by the jurist known as Gratian.