Johannes Cotto

Johannes Cotto (John Cotton, Johannes Afflighemensis) (fl. c. 1100) was a music theorist, possibly of English origin, most likely working in southern Germany or Switzerland. He wrote one of the most influential treatises on music of the Middle Ages, one which included unusually precise directions for composing chant and organum.

Next to nothing is known about his life; indeed his identity has been a matter of controversy among scholars. Formerly it was thought he was from Lorraine or Flanders, based on a dedication he made in his treatise, but other more recent evidence suggests that he may have been a John Cotton from England who worked under an abbot named Fulgentius at or near St. Gallen (in modern Switzerland). Some of the more compelling evidence includes his knowledge of chant peculiarities of that region, notational idiosyncrasies found only in southern Germany, and his use of the old Greek modal names such as Phrygian and Mixolydian, something which was mainly done in Germany.

His De musica was one of the most widely copied and distributed music treatises of the medieval period, with some copies appearing even after 1400. Most likely it was written around 1100, and its comments, examples, and suggestions correspond closely with the music of the contemporary St. Martial school and Codex Calixtinus, as well as the material in the treatise Ad organum faciendum (also known as the "Milan Treatise") from about the same time.

De musica consists of twenty-seven chapters, and covers a wide range of musical topics. Unlike many medieval treatises, it largely avoids metaphysical speculations, instead functioning as a practical guide for a working musician. Much of the source material is from Guido of Arezzo, Boethius, Odo of Cluny, Isidore of Seville, and Hermannus Contractus.

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