Musica enchiriadis is an anonymous musical treatise from the 9th century. It is the first surviving attempt to establish a system of rules for polyphony in classical music. The treatise was once attributed to Hucbald, but this is no longer accepted. Some historians once attributed it to Odo of Cluny (879-942).
This music theory treatise, along with its companion commentary, Scolica enchiriadis, were widely circulated in medieval manuscripts, typically coupled with Boethius' De Institutione Musica. It consists of nineteen chapters; the first nine are devoted to notation, modes, and monophonic plainchant.
Chapters 10-18 deal with polyphonic music. The author shows how consonant intervals should be used in order to compose or improvise polyphonic music in early Middle Ages. A number of examples of organum, an early style of note-against-note polyphony, are included in the treatise. Musica Enchiriadis also shows rules for performing music and gives some early indications of character for some works, as the Latin words 'morosus' (sadly) or 'cum celeritate' (fast). The last, nineteenth, chapter relates the legend of Orpheus.
The scale used in the work, which is based on a system of tetrachords, appears to have been created solely for use in the work itself, rather than taken from actual musical practice. The treatise also uses a very rare system of notation, known as Daseian notation. This notation has a number of figures which are rotated ninety degrees to represent different pitches.
A critical edition of the treatises was published in 1981, and an English translation in 1995.