reflected a current practice; in the absence of many surviving 11th-century manuscripts it is difficult to date when the switch from mostly parallel to mostly contrary motion occurred). One short passage in De musica which has attracted much attention is his description of organum sung with several notes in the organal voice versus one note in the underlying chant, one of the earliest examples of polyphony escaping from the straitjacket of single note against single note. Johannes may have been a composer, though no music attributed to him has survived. His directions for composing melody, with their careful and practical instructions involving pacing, position of high and low notes, and use of recognizable figurations at different pitch levels seem to imply that he may have had some experience himself. Manuscripts There are two manuscripts at Vienna, and one each at Leipzig, Paris, Rome, and Antwerp. A sixth, from which Gerbert printed his edition, was destroyed in the fire at St. Blaise Abbey in 1768. The Vatican copy is said by Fétis to contain much of the best text. The exact date of the treatise is unknown. The Vienna and St. Blaise copies entitle it merely "Joannis Musica", while the Paris and Antwerp copies have the name of Cotton or Cottonius. The anonymous monk of Melk Abbey who copied the work, says that there was a learned English musician known as Joannes, and the English origin of the work is rendered more probable by the author's dedicating it "Domino et patri suo venerabili Anglorum antistiti Fulgentio," though the latter, like Cotton, cannot be identified. One theory attributes the work to Pope John XXII, but this rests on the very slight foundation that the author styles himself "Joannes servus servorum Dei." Gerbert has pointed out that this title was not solely used by popes, and it seems unlikely that a pope would address a bishop with deference. The work is also clearly of earlier date, for it speaks of neums being in ordinary use at the time of writing. Another theory ascribes it to a certain "Joannes Scolasticus", a monk of St. Matthias' Abbey at Trier, all that is known of whom is that he was living about 1047, and that he wrote much music, but there seems to be no reason why the work should not have been written by the unknown Englishman, John Cotton. From internal evidence its date appears