The notational system of mensural music

The basic idea of mensural music is that rhythm can be represented by the shape of the notes. Mensural notation establishes a new notational system that enables the encoding of exact rhythmic values in the figures of the notes.

During the second half of the 13th century musical composition evolved in a way that facilitated the development of a new method of measuring musical time. As we learned last week, modal notation could not provide a system that was differentiated enough to notate elaborate rhythm. Therefore, a new way of visualizing note values emerged. The duration of a note was no longer represented through the concept of numbers (Step 3.5), but instead it was inscribed in the shape of the signs. A fundamental shift took place from rhythm as numerus to rhythm as figura. Notational signs, both single and ligated notes, became loaded with a new semiotic charge - their duration was now recognizable from the shape of the square notes:

Table of notational signs

The older names of virga and punctum were replaced by longa, brevis and semibrevis, the latter taking the form of a small rhombus. A sign, which had already been in use in modal notation and which had indicated a longer note, was also introduced under the name of duplex longa or maxima. The relation between maxima and longa can be binary or ternary:

Notational signs

The relation between longa, brevis and semibrevis is always ternary:

Notational signs

The ligature forms of the French square notation were also incorporated in the system of mensural music. A specific duration was assigned to each ligature as well, depending on the shape of the beginning or the ending of the figures. Here you can see a few examples:

Notational signs

You can learn more about the ligatures by having a look at the table in Step 4.4.

In mensural notation the plica (Step 3.2) is also still in use. In fact it is responsible for a systematic differentiation. In musical manuscripts from the 13th century you find a sign for the longa with plica and a sign for the brevis with plica. The difference is marked by the length of the plica stroke: plica brevis

Notational signs

Two music theorists summed up this historical development in their treatises: Magister Lambertus in his Tractatus de Musica (1270) and Franco of Cologne in his Ars Cantus Mensurabilis (1280). This newly introduced notation method put the emphasis on the concept of the figura. The shape, the figure of the notes was no longer just an extrinsic feature of writing; it became an essential and highly significant aspect of musical notation. Mensural notation is a well-organised notational system based on the knowledge of a complex system of rules (Steps 4.3 and 4.4). Learning these rules and knowing how to handle some tricky cases of ambiguous notation, you will be able to read and transcribe mensural music from the 13th century by yourself.


Franco de Colonia. Ars cantus mensurabilis. G. Reaney/A. Gilles: CSM 18, Rome 1974.

Lambertus (Quidam Aristoteles). Tractatus de musica, E. de Coussemaker, Scriptorum de musica medii aevi, vol. 1: Hildesheim, 1963, p. 251–281.


Montpellier, Faculté de Médecine H 196, (ca. 1270)

Bamberg, Staatsbibliothek, Lit. 115, Ed. IV.6, (ca. 1290)

Las Huelgas, Monasterio de Santa Maria la Real, without shelfmark (ca. 1300–1325)

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From Ink to Sound: Decoding Musical Manuscripts

University of Basel