Under the name bestiary comes a medieval book that is a collection of short descriptions of different real or imaginary animals, birds and even rocks that is often accompanied by a moralising explanation. This reflected the belief that the world itself was literally the Word of God, and that therefore every living thing had its own special meaning. For example, the pelican, which was believed to tear open its breast to bring its young to life with its own blood, was a living representation of Christ. This symbolism was well known at the time - animals depicted in religious paintings were not just animals, they were symbolic of other meanings in the painting. Bestiary animals were also found in church sculpture, where the familiar images would remind the viewer of the story and its aligorical meaning.
One important part of most bestiaries was the illustrations. They added a lot to the descriptions, serving then as an educational tool for the illiterate.
The most well-known bestiary of that time is the Aberdeen Bestiary. There are many others; over 50 manuscripts survive today.