A Bestiary is a collection of short descriptions about all sorts of animals, real and imaginary, birds and even rocks, accompanied by a moralising explanation. Although it deals with the natural world it was never meant to be a scientific text and should not be read as such. Some observations may be quite accurate but they are given the same weight as totally fabulous accounts. The Bestiary appeared in its present form in England in the twelfth century, as a compilation of many earlier sources, principally the Physiologus.