Isorhythmic motet

In western music, a motet is a mainly vocal musical composition, of highly varied form and style, from the late medieval era to the present. The motet was one of the pre-eminent polyphonic forms of Renaissance music. According to Margaret Bent, "a piece of music in several parts with words" is as precise a definition of the motet as will serve from the 13th to the late 16th century and beyond. The late 13th-century theorist Johannes de Grocheo believed that the motet was "not to be celebrated in the presence of common people, because they do not notice its subtlety, nor are they delighted in hearing it, but in the presence of the educated and of those who are seeking out subtleties in the arts".

In the early 20th century, it was generally believed the name came from the Latin movere, ("to move"), though a derivation from the French mot ("word", or "phrase"), had also been suggested. The Medieval Latin for "motet" is motectum, and the Italian mottetto was also used. If the word is from Latin, the name describes the movement of the different voices against one another. Today, however, the French etymology is favoured by reference books, as the word "motet" in 13th-century French had the sense of "little word". In fact, the troped clausulas that were the forerunner of the motet were originally called motelli (from the French mot, "word"), soon replaced by the term moteti.

The earliest motets arose in the 13th century from the organum tradition exemplified in the Notre Dame school of Léonin and Pérotin. The motet probably arose from clausula sections, usually strophic interludes, in a longer sequence of organum, to which upper voices were added. Usually the clausula represented a strophic sequence in Latin which was sung as a discant over a cantus firmus, which typically was a plainchant fragment with different words from the discant. The motet took a definite rhythm from the words of the verse, and as such appeared as a brief rhythmic interlude in the middle of the longer, more chantlike organum. Because the system of writing music used up until the development of modal rhythmic notation around 1230 lacked individual notational symbols with which to express rhythms in music, almost all of the earliest motets (like the clausulas they replaced) are for tenor and duplum (or motetus) only. The main exception is the conductus motet, in which the parts proceed in essentially homophonic rhythms.

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