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.
Bestiaries were popular in the
12th century and were mainly
compilations of earlier texts especially
the Physiologus.
Very important part of all bestiaries were illustrations. They added
a lot to the descriptions, serving then as an educational tool.
The most important of bestiaries of that time is
Aberdeen Bestiary.
T.H. White's translation of a medieval bestiary can be found on-line at
http://libtext.library.wisc.edu/Bestiary/