Rhythmic mode

In medieval music, the rhythmic modes were patterns of long and short durations (or rhythms) imposed on written notes which otherwise appeared to be identical. Modal notation, which was developed by the composers of the Notre Dame School from 1170 to 1250, replaced the even and unmeasured rhythm of early polyphony and plainchant with patterns based on the metric feet of classical poetry, and was the first step towards the development of modern mensural notation (Hoppin 1978, p. 221). The Rhythmic modes of Notre Dame Polyphony were the first indication in written music of specified duration of the note since ancient Greece.

Though the use of the rhythmic modes is the most characteristic feature of the music of the late Notre Dame school, especially the compositions of Pérotin, they are also predominant in much of the rest of the music of the ars antiqua through about the middle of the 13th century. Composition types which were permeated by the modal rhythm include Notre Dame organum (most famously, the organum triplum and organum quadruplum of Pérotin), conductus, and discant clausulae. Later in the century, the motets by Petrus de Cruce and the many anonymous composers, which were descended from discant clausulae, also used modal rhythm, often with much greater complexity than was found earlier in the century: for example each voice sometimes sang in a different mode, as well as a different language.^{[citation needed]}

In most sources there were six rhythmic modes, as first explained in the anonymous treatise of about 1240, De mensurabili musica (formerly attributed to Johannes de Garlandia, who is now known to have edited it extensively in the late 13th century).^{[citation needed]} Each mode consisted of a short pattern of long and short note values ("longs" and "breves") corresponding to a metrical foot, as follows:

1. Long-short (trochee)
2. Short-long (iamb)
3. Long-short-short (dactyl)
4. Short-short-long (anapest)
5. Long-long (spondee)
6. Short-short (pyrrhic)

Although this system of six modes was recognized by medieval theorists, in practice only the first three appear to have been the standard patterns of the modal period, with the second mode being less frequently used than the first and third.^{[citation needed]} The fourth mode is almost never seen, and the fifth and sixth are hardly modes at all in view of their uniform rhythm.^{[citation needed]} The fifth mode is normally used only in the lowest voice (or tenor) (Hughes 1954, 320).

Modern transcriptions of the six modes usually are as follows:

1. Quarter (crotchet), eighth (quaver) (generally barred, therefore, in 3/8)
   
2. Eighth, quarter (barred in 3/8)
   
3. Dotted quarter, eighth, quarter (barred in 6/8)
   
4. Eighth, quarter, dotted quarter (barred in 6/8)
   
5. Dotted quarters (barred in either 3/8 or 6/8)
   
6. Eighths (barred in 3/8 or 6/8)
   

Devised in the late 12th century,^{[citation needed]} they used stereotyped combinations of ligatures (joined noteheads) to indicate the patterns of long notes (longs) and short notes (breves), enabling a performer to recognize which of the six rhythmic modes was intended for a given passage. Linked notes in groups of 3, 2, 2, 2, etc. indicate the first mode, 2, 2, 2, 2, … 3 the second mode, 1, 3, 3, 3, 3, etc. the third mode, 3, 3, 3, … 1 the fourth mode, 3, 3, 3, 3, etc. the fifth mode, and 4, 3, 3, 3, etc. the sixth mode (Hughes 1954, 323–24). The reading and performance of the music notated using the rhythmic modes was thus based on context. After recognizing which of the six modes applied to a passage of neumes, a singer would generally continue on in that same mode until the end of a phrase, or a cadence. In modern editions of medieval music, ligatures are represented by horizontal brackets over the notes contained within it.

All the modes adhere to a ternary principle of metre, meaning that each mode would have a number of beat subdivisions divisible by the number 3. This is speculated^{[weasel words]} to have its origins in theology where the trinity was perfection and, as all music strives for perfection, it therefore had to be divisible by the number 3. Less speculatively, the flexibility of rhythm possible within the system allows for variety and avoids monotony. Notes could be broken down into shorter units (called fractio modi) or two rhythmic units of the same mode could be combined into one (extensio modi).

An ordo (plural ordines) is a phrase constructed from one or more statements of one modal pattern and ending in a rest. Ordines were described according to the number of repetitions and the position of the concluding rest. "Perfect" ordines ended with the first note of the pattern followed by a rest substituting for the second half of the pattern, and "imperfect" ordines ended in the last note of the pattern followed by a rest equal to the first part. Imperfect ordines are mostly theoretical and rare in practice where perfect ordines predominate (Hoppin 1978, p. 223).

Other writers who covered the topic of rhythmic modes include Anonymous IV, who mentions the names of the composers Léonin and Pérotin as well as some of their major works, and Franco of Cologne, who recognized the limitations of the system and was the first to propose a notational method whereby the duration of any note would be signified by its shape.^{[citation needed]} After Garlandia, many theorists tried to include the semibreve in the system. Lambertus increased the number of modes to 9.^{[citation needed]}

References and further reading

• Apel, Willi. The Notation of Polyphonic Music, 900-1600, 5th edition, revised and with commentary. Publications of the Mediaeval Academy of America, no. 38. Cambridge, Mass.: Mediaeval Academy of America, 1961.
• Articles "Rhythmic mode", "Johannes de Garlandia," "Franco of Cologne," in The New Grove Dictionary of Music and Musicians, ed. Stanley Sadie. 20 vol. London, Macmillan Publishers Ltd., 1980. ISBN 1-56159-174-2.
• Grout, Donald Jay, J. Peter Burkholder, and Claude V. Palisca. A History of Western Music, 7th edition. New York: W. W. Norton, 2006. ISBN 0393979911
• Hoppin, Richard H. Medieval Music. New York: W. W. Norton & Co., 1978. ISBN 0-393-09090-6.
• Hughes, Dom Anselm. "Music in Fixed Rhythm". In New Oxford History of Music, vol. 2: "Early Medieval Music up to 1300", edited by Dom Anselm Hughes, 311–52. London New York, & Toronto: Oxford University Press, 1954.
• Parrish, Carl, The Notation of Medieval Music. London: Faber & Faber, 1957.
• Randel, Don Michael, and Willi Apel (eds.). The New Harvard Dictionary of Music. Cambridge, Massachusetts: Belknap Press of Harvard University Press, 1986. ISBN 0-674-61525-5.
• Wellesz, Egon (ed.) New Oxford History of Music, vol. 1: "Ancient and Oriental Music". London & New York: Oxford University Press, 1957.