Important developments in Italian theory occurred in the early 11th century. The
Dialogus de musica, formerly attributed to Odo of Cluny, was written around Milan, and
Guido d’Arezzo in four treatises developed a concise practical alternative to Musica
enchiriadis, codified advances in staff notation, and developed a system of solmization.
In the late 11th and 12th centuries, these texts were transmitted to France and
subsequently exercised critical influence in French musical thought and practice.
Ars Antiqua, Ars Nova. By the 12th century, the harmonic issues of early-medieval
theory had been for the most part resolved: a system based on the periodic octave; a
theory of consonance organized around the fourth, fifth, and octave; a theory of the
liturgical modes systematized on four finals; and an elementary theory of organum or
polyphonic voice leading were all set to be recapitulated in later treatises. The all-
pervading issue of subsequent musical reflection became the organization of time in
music, or the fundamental principles of rhythm. Giving rise to this issue was the rapid
development of polyphony during the 11th and 12th centuries and the necessity of
bringing some order to two or more voices singing at the same time.
In the late 11th and 12th centuries, intellectual life began to shift from rural monastic
centers to urban cathedral schools, which subsequently evolved into the medieval
universities. Paris became a center of both intellectual and musical activities during the
12th and 13th centuries, and the musical accomplishments of central France during the
period subsequently became known as the Ars Antiqua, a musical movement that
witnessed the first great flowering of a polyphonic repertoire with a rational rhythmic
foundation. The most outstanding musical theorists of the 13th century, Johannes de
Garlandia and Franco of Cologne, were active in Paris, where both magistri were
probably associated with the University of Paris. Following scholastic traditions of
thought, Johannes de Garlandia divided music into genre, species, and divisions in two
treatises, De plana musica and De mensurabili musica. Johannes presented a
systematized treatment of rhythmic theory organized around rhythmic modes and defined
the three styles of measured polyphony as discant, copula, and organum. Franco of
Cologne’s Ars cantus mensurabilis was widely circulated throughout western Europe
during the 13th century; while reflecting scholastic terminology, Franco’s work was a
thoroughly practical treatise that extended the rational order of rhythmic notation from
the various species of organum (sine littera) to the texted motets (cum littera).
Two remarkable monuments in the history of musical thought grew out of the
scholastic culture of Paris during the late 13th and early 14th centuries: Jerome of
Moravia’s Tractatus de musica and Jacques de Liège’s Speculum musice. The Dominican
Jerome of Moravia, in what amounts to a musical summa, sought to review as thoroughly
as possible the contemporary state of musical thought, drawing on sources as disparate as
Boethius, Isidore, Guido, Johannes Affligemensis, al-Farabi, Richard of Saint-Victor,
Hugh of Saint-Victor, Johannes de Garlandia, Franco of Cologne, and others. Jerome
continued the tradition of discussing music within the context of the Quadrivium,
presented the basic theory needed for performance of liturgical chant (musica plana) and
offered a thorough collection of texts treating the new rhythmic practices (musica
mensurabilis). The earliest extant treatise developing the theory of rhythmic modes,
Discantus positio vulgaris, is in fact preserved in Jerome’s Tractatus. Jerome’s musical
summa is preserved in only one manuscript (B.N. lat. 16663), willed to the Sorbonne by
Petrus of Limoges in 1304.
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