2. Ordering through mensuration and range

After the choice of the basic melisma, called the color of the motet, the work was, musically speaking, as yet formless. By the rhythmicization of the color, in this case containing 30 notes, the composer gives a form to his motet; the resulting tenor constitutes ‘its bones’, as the theorist Johannes de Grocheio called it around 1300. On this foundation the upper voices are built.

A clear hierarchy exists in the movement of M1, which is at the same time a historical one. 

The tenor has the largest values, longae and breves, the oldest note types with which the whole development of mensuration began in the organum of the early thirteenth century; this mensuration level is called modus.



The motetus adds semibreves to these, such as appeared in the later thirteenth-century motet on the level of tempus.




The triplum also contains the most recent values of the fourteenth century, the minimae, on the level called prolatio (the motetus, too, has minimae but only six). 



Exceptionally, all the mensuration levels are perfect, i.e. ternary: the longa is worth three breves, the brevis three semibreves and the semibrevis three minimae (usually the mensural levels are mixed, with perfect modus, imperfect tempus and perfect prolatio being the most common combination). In the transcription these values are usually reduced by 4, i.e. the longa is transcribed as a whole note, the brevis as a half note, the semibrevis as a quarter note and the minima as an eighth note.

To make this element easier to follow, the following extract presents a different timbre for each voice, emphasising the tenor and therefore the way the other voices refer to it.

Sound and Score    ¦    Facsimile

When the tenor melody has been sung completely, a change in movement takes place: its melody is repeated but thrice as fast. This is the result of the so-called diminution: the original values, longae and breves, are replaced by the next smaller ones, breves and semibreves and thus the tenor’s movement becomes three times quicker.

Typical for motets from this time is their structuring in rhythmically fixed patterns, called taleae which are strictly identical in the tenor, less strictly so in the upper voices; the tendency is that the later motets have more such identical patterns in the upper voices than the earlier ones which may have very little of it. This is usually called isorhythm,[1] and it is found mainly in the larger values and in the hockets (a technique where notes in one part coincide with rests in another and then quickly are exchanged. A relatively slow use of this technique was included in the example above, b. 22-4). Especially in the diminution sections of a motet such hockets and isorhythmic patterns are more frequent. A few motets are pan-isorhythmic or nearly so, i.e. that each talea is isorhythmic in all three voices (M15 and M13 are examples of this development).

In M1 the 30 color notes are divided over six taleae of five notes and two rests each (see first facsimile extract above).

Sound and Socre

Recurring rhythmic patterns in the upper voices do occur, but only when two tenor taleae are combined the isorhythmic construction of the upper voices becomes clear; the audibly most obvious signs of it are the slow hockets mentioned above which appear in the 22nd to 24th measures of each double talea, and marked in the poems by very short verses of two syllables. Thus the motet consists of three double taleae of 36 breves and three diminished ones of 12 breves, adding up to the symbolic number of completeness and stability, 144. These taleae correspond with the strophic form of the upper voice texts. The increase of intensity by the tenor diminution can also be seen in the texts, where, from this point on smaller strophes appear.

In intervallic structure a motet is also hierarchically built, although less strictly so. Generally the tenor proceeds in small intervals like seconds or thirds, with the occasional leap of a fourth or a fifth. In the four motets where a contratenor is added (M5 and 21-23) it stays in the same register and is set in the same large time values as the tenor, but usually has larger intervals and leaps. The motetus sings at a distance of, generally, a fifth above the tenor, but may range from unison to an octave above the tenor. On special occasions, though, it can rise above the triplum or descend below the tenor. The triplum sings mostly at an octave above the tenor but may descend to a fifth or even less above it or rise to an octave plus fifth. Whereas the triplum usually follows the tenor in a gradual melodic movement with only few leaps, the motetus is often the unruly voice, jumping to and fro in very large leaps and register changes, and in some cases causing conflicts.  


Jacques Boogaart

[1] For a qualification and relativation of the term Isorhythm, introduced only at the beginning of the twentieth century, see Margaret Bent, ‘What is Isorhythm?’, in David Cannata [et al.], eds, Quomodo cantabimus canticum? Studies in Honor of Edward H. Roesner. Middleton WI: American Institute of Musicology, 2008: 121-43.