During the first centuries of the Christian era, liturgical music was strongly influenced by Hebrew and Byzantine traditions. Most of the songs are passed on by oral tradition and for a long time the human voice was the only accepted source of music in churches. The first western musical notations emerge during the 9th century, during an effort to unite liturgy and cultural practices, promoted by Pope Gregory I (540-590), then Charlemagne (742-814). Music writing consisted then of mnemonic signs and is materialized by signs added above the texts which are supposed to be sung. The notes give no indication on the pitch, the duration, or the rhythm: they are the first neumes.
Missale, late 11th century. Latin 12054, fol. 8r. ©Gallica