A bestiary is a collection of short descriptions about all sorts of birds, beasts and animals, both real and imaginary. Often bestiary is too narrow a description, and the medieval term "natural history" is more apt as stones, minerals, herbs and trees might also be studied, especially in later periods. The bestiary became a popular form in England in the 12th Century. One example of the late medieval version of a bestiary is John Maplet's A Greene Forest.
Two schools of medieval bestiary are known, each descended from early Greek authors. The first type is very factual, transmitting myths only through ignorance. Best known are the works of Pliny the Elder, but a plethora of translations and works based on extended or condensed versions of this existed.
The other kind of bestiary is not concerned with accurate descriptions of the animals, but with using the animals to explain or portray a message. Early medieval bestiaries use the animals to give a moralising explanation of the animals traits and how that reflects upon Christianity. From the 13th century onwards, "bestiaries of love" used the stories of the animals as a vehicle for the male to woo a lady. It tells fine messages about the desirable attributes of an animal, and is meant to be a message about the man.