Ars Magica is set in Mythic Europe, a fantasy reinterpretation of the historical European Middle Ages. The most important characters in play are Magi, powerful magicians wielding the magical powers of legend and fantasy, who congregate in Covenants, along with their followers, often, but not always, for common purpose. Most Magi within Mythic Europe belong to a society of wizards called the Order of Hermes, founded by the wizard Bonisagus who created a single theory of magic and a defense that allowed Magi to gather without fear of violence or treachery.