''Ars cantus mensurabilis'' (Latin for ''the art of the measurable song'') is a

music theory Music theory is the study of the practices and possibilities of music. ''The Oxford Companion to Music'' describes three interrelated uses of the term "music theory". The first is the "rudiments", that are needed to understand music notation (ke ...

treatise from the mid-13th century, c. 1250–1280 written by German music theorist

Franco of Cologne Franco of Cologne (; also Franco of Paris) was a German music theorist and possibly a composer. He was one of the most influential theorists of the Late Middle Ages, and was the first to propose an idea which was to transform musical notation per ...

. The treatise was written shortly after ''

De Mensurabili Musica ''De Mensurabili Musica'' (concerning measured music) is a musical treatise from the early 13th century (medieval period, c. 1240) and is the first of two treatises traditionally attributed to French music theorist Johannes de Garlandia; the othe ...

'', a treatise by Johannes de Garlandia, which summarised a set of six

rhythmic mode In medieval music, the rhythmic modes were set patterns of long and short durations (or rhythms). The value of each note is not determined by the form of the written note (as is the case with more recent European musical notation), but rather by i ...

s in use at the time.Christensen, Thomas. ''The Cambridge History of Western Music Theory'', (Cambridge: Cambridge University Press, 2002), p. 628 In music written in rhythmic modes, the duration of a note could be determined only in context. ''Ars cantus mensurabilis'' was the first treatise to suggest that individual notes could have their own durations independent of context. This new rhythmic system was the foundation for the

mensural notation Mensural notation is the musical notation system used for European vocal polyphonic music from the later part of the 13th century until about 1600. The term "mensural" refers to the ability of this system to describe precisely measured rhythm ...

system and the ars nova style.

References

{{Authority control Ars antiqua Musical notation European rhythm Medieval music manuscript sources Music textbooks 13th-century Latin books Medieval music theory