“bestiaries: Allegorical poems or books giving descriptions of various animals or stories concerning them, with Christian application or moral appended to each. Although the characteristics and habits assigned to each animal were largely legendary, bestiaries were often treated during the Middle Ages as treatises on natural history, as well as moral instruction, and were highly popular.
The beast-fable, popular from Aesop to the medieval Roman de Renart, was usually satirical and pragmatic in its moral; a 4th-century work in Greek was probably the first to turn animal descriptions into specifically Christian allegory, and its translations into Latin Physiologi were the basis of most English and Continental bestiaries. The best known are the Latin Physiologus (11th century) by the abbot Theobaldus, the Bestiary by the Anglo-Norman poet Phillippe de Thaun, and an anonymous Middle English Bestiary (c1250).”
Excerpted from: Murphy, Bruce, ed. Benet’s Reader’s Encyclopedia, Fourth Edition. New York: Harper Collins, 1996.