Editing Medieval music (section)

===Early polyphony: organum===
{{main|Organum}}
Around the end of the 9th century, singers in monasteries such as [[Abbey of St. Gall|St. Gall]] in Switzerland began experimenting with adding another part to the chant, generally a voice in [[contrary motion|parallel motion]], singing mostly in perfect [[perfect fourth|fourths]] or [[perfect fifth|fifths]] above the original tune (see [[interval (music)|interval]]). This development is called [[organum]] and represents the beginnings of [[counterpoint]] and, ultimately, [[harmony]].<ref>{{Cite book|last=Leech-Wilkinson, Daniel.|url=http://worldcat.org/oclc/122283268|title=The modern invention of medieval music : scholarship, ideology, performance|date=2007|publisher=Cambridge University Press|isbn=978-0-521-03704-4|oclc=122283268}}</ref> Over the next several centuries, organum developed in several ways.

The most significant of these developments was the creation of "florid organum" around 1100, sometimes known as the [[school of St. Martial]] (named after a monastery in south-central France, which contains the best-preserved manuscript of this repertory). In "florid organum" the original tune would be sung in long notes while an accompanying voice would sing many notes to each one of the original, often in a highly elaborate fashion, all the while emphasizing the perfect [[consonance and dissonance|consonances]] (fourths, fifths and octaves), as in the earlier organa. Later developments of organum occurred in England, where the interval of the [[Interval (music)|third]] was particularly favoured, and where organa were likely improvised against an existing chant melody, and at [[Notre Dame school|Notre Dame]] in Paris, which was to be the centre of musical creative activity throughout the thirteenth century.

Much of the music from the early medieval period is [[Anonymous work|anonymous]]. Some of the names may have been poets and lyric writers, and the tunes for which they wrote words may have been composed by others. Attribution of monophonic music of the medieval period is not always reliable. Surviving manuscripts from this period include the [[Musica Enchiriadis]], [[Codex Calixtinus]] of [[Santiago de Compostela]], the [[Magnus Liber]], and the [[Winchester Troper]]. For information about specific composers or poets writing during the early medieval period, see [[Pope Gregory I]], [[Godric of Finchale|St. Godric]], [[Hildegard of Bingen]], [[Hucbald]], [[Notker of St Gall|Notker Balbulus]], [[Odo of Arezzo]], [[Odo of Cluny]], and [[Tuotilo|Tutilo]].