Manuscripts in which music appears, whether ecclesiastical or secular, were sometimes illuminated, the extent of illumination depending largely on patronage and purpose. Depictions of musicians and instruments frequently appear in medieval manuscripts as drolleries and in initials and bas-de-page scenes. Music was incorporated into the Christian liturgy early on, influenced by the use of music in the synagogue. The study of music theory was part of the Antique and medieval Liberal Arts syllabus. Plainchant (unison singing, originally unaccompanied) was the traditional music of the western Church. From about 1000, vocal polyphony (music with two or more melodically independent parts) was being practiced at Winchester in England. A particularly rich repertoire of polyphony came from the cathedral of Notre-Dame in Paris. Polyphony made certain chants of the Mass longer and more complex. From the mid-thirteenth century on, liturgical polyphony shared a number of characteristics with secular music. There is little early written evidence for secular music, although there was probably a rich oral tradition, but collections of the songs of troubadours and trouvères survive from the mid-thirteenth century on, by which time the courtly poet-composer had achieved professional status. The notation of liturgical music initially appears in the form of neumes -- graphic symbols written above the text and indicating the rise and fall of melodic movement or repetitions of the same pitch. Twelve to fifteen regional families of neumes have been identified. They were commonly written on a four-line staff beginning in the mid-eleventh century. Two hundred years later, eastern European music manuscripts adopted Gothic notation, produced with a thick, square-cut nib, with the points and curves of earlier neumes being replaced by broader, more angular forms. A similar development in the Île de France gave rise to the use of square notation in the late twelfth century, especially in France and Italy. Alphabetical notation is also sporadically encountered from Antiquity on in a theoretical context. For liturgical manuscripts with sung components, see Antiphonal, Breviary, Gradual, Hymnal, Kyriale, Missal, Sequentiary and Troper.
Michelle Brown, Understanding Illuminated Manuscripts (Malibu, CA: J. Paul Getty Museum in association with the British Library, c1994).