Guido Bonatti

Guido Bonatti was an Italian mathematician, astronomer and astrologer, who was the most celebrated astrologer of the 13th century. Bonatti was advisor of Frederick II, Holy Roman Emperor, Ezzelino da Romano III, Guido Novello da Polenta and Guido I da Montefeltro. He also served the communal governments of Florence, Siena and Forlì. His employers were all Ghibellines, who were in conflict with the Guelphs, and all were excommunicated at some time or another. Bonatti's astrological reputation was also criticised in Dante's Divine Comedy, where he is depicted as residing in hell as punishment for his astrology.