A bestiary, or bestiarum vocabulum, is a compendium of beasts. Originating in the Ancient world, bestiaries were made popular in the Middle Ages through illustrated volumes that described various animals and even rocks. The illustration of each beast was usually accompanied by a moral lesson. This reflected the belief that the world itself was the Word of God, and that every living thing had its own special meaning. The bestiary, then, is also a reference to the symbolic language connected to animals in Western Christian art and literature.