I discovered this review of a book entitled Medieval Bestiary and I reproduce it here as it is very interesting:
“Bestiary” is a translation of a medieval book about animals, originally written in Latin during the 13th century, somewhere in England. The main source for this bestiary was another bestiary, compiled during the 12th century, and also translated to English as “The Book of Beasts”. Thus, the text of the two books are very similar.
We are used to a modern, scientific view of nature and animals. The Middle Ages saw things differently. Animals weren’t seen as random products of blind, natural forces. They were created by God for the edification of the human race.
Indeed, Adam named all animals in the Garden of Eden, each name reflecting their true character. Animals were not just brute beasts. They carried a moral message, directed to sinful humanity. They also carried a hidden, mystical meaning, which somehow paralleled the message of the Bible itself! All the world was seen as an enchanted, magical place, with each thing a symbol for deeper, moral or spiritual, realities.