This document summarizes the development of polyphony from its origins in organum through the Notre Dame school in the late 12th/early 13th centuries. It discusses key figures like Léonin and Perotin who expanded organum to include more voices with intricate rhythms. Other developments discussed include clausulae, motets which added secular texts, and conductus which were freely composed sacred songs. The document concludes by introducing mensural notation which developed in the late 13th century to notate the increasingly complex rhythms of polyphonic music.

1. CHAPTER 2:
POLYPHONY TO 1300
A History of Music in Western Culture, 4th edition, Mark Evan Bonds

2. Organum
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• Polyphonic work consisting of an original
plainchant melody in ONE voice, plus at
least one additional voice above or below
~850 AD
• Additional voice runs parallel to the
plainchant melody at a constant interval
Parallel organum
• The simultaneous combination of
independent musical lines
Counterpoint

3. Notre Dame Organum
Léonin
◦ ~1163 – Léonin wrote large quantities of
organa for responsorial chants
◦ Responsorial – soloist or small group in unison
sings a phrase; the chorus responds - THESE
were monophonic
◦ The soloist portions were lengthy, 2-voice
organa
Perotin
◦ Younger contemporary of Léonin - added a 3rd
voice (triplum) and on rare occasion a 4th voice
(quadruplum)
◦ Rhythmically intricate – demanded a higher level
of singing than most monks could provide
◦ Rhythm provided an energy that drove the
music constantly forward

4. Clausula and Motet
◦ Clausulae – brief polyphonic sections of
measured organum that could be substituted at
will into a larger piece
◦ A clausula is NOT an independent composition
◦ Very much like tropes, but inserted into a
composition, not a plainchant
◦ Impetus comes from the desire to write new
music by adding layers of musical
“commentary” above the plainchant
◦ No text included!
◦ Motet – added SECULAR TEXT
◦ ~1185-1250: new text added to an existing
clausula to be performed outside the church
◦ Sung in the vernacular, not liturgical Latin
◦ Texted duplum = motet because it had words
(Fr. mot = word)
◦ Polytextual motet = different voices sing
different text simultaneously (<1250 AD)
◦ Multiple repetition of rhythmic and melodic
ideas – isorhythm

5. Conductus
◦ Probably to be performed while a priest and his attendants entered and left
the church
◦ Not based on borrowed material of any kind – completely new musical
material
◦ Texts are freely-composed poems written in metered verse, strongly
syllabic and strongly metrical
◦ All voices move in roughly the same rhythm

6. MENSURAL NOTATION
◦ Mensural = metered, measured, divided into units
◦ ~1260-1280 AD notational system of writing the tune (or the mode) began to also reflect the rhythm.
◦ Old style ligature groupings could not indicate the new complex rhythms – a change was needed
◦ Franco of Cologne codified a system retaining note shapes BUT
◦ …he assigned specific rhythmic meanings to each of the various note shapes!
◦ Significance of this innovation completely changed Western music: it provided composers with a system
capable of greater flexibility, and is basically still in place today (with modification)