Leonin and Perotin: Musical Contributions, Polyphony & Ars Antiqua

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  1. 0:05 Polyphony
  2. 1:17 Leonin and Perotin
  3. 2:13 Ars Antiqua
  4. 2:56 Organum
  5. 4:39 Rhythm
  6. 6:20 Lesson Summary
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Taught by

Liz Diamond-Manlusoc

Liz has taught music for K-12 and beyond. She holds a master's degree in Education Media and Design Technology.

The development of polyphonic, or multi-part music, was a fundamental part of the late Medieval period, and it forever influenced music thereafter. In this lesson, learn about how polyphony developed through the Medieval church composers Leonin and Perotin.


In the early days of the Medieval Church, music was regulated to have just one singing part. Eventually, singing the same thing as everyone else all the time became boring, and the Church decided that maybe two singing parts wasn't so bad, as long as it stayed within reason. So, around the middle of the 12th century, polyphony was allowed.

Polyphony is heard when two or more independent melodies are sung or played simultaneously. This makes sense, since 'poly' means 'many,' and 'phony' means 'to sound.' In polyphony, the pitches and rhythms of each musical part are different from one another, yet they are sung or played at the same time. Think of a round, like 'Row, Row, Row Your Boat'. If you and your friend are singing the song as a round, you are singing two different parts at the same time.

Leonin and Perotin

There is no specific date or documentation that shows exactly when polyphony started being used in the Church, but two French composers, Leonin and his student Perotin, of the Notre Dame Cathedral in Paris, are generally credited with composing the first significant polyphonic church music.


Leonin, sometimes referred to as 'Leoninus,' is thought to have lived from 1150-1201. He is known for being the first composer of polyphonic music that we can identify by name. Leonin's music was generally in two vocal parts.


Perotin, sometimes referred to as 'Perotinus,' was Leonin's student. He is thought to have lived from 1170-1236 and he extended Leonin's efforts by composing music with three or four vocal parts.

Ars Antiqua

This new polyphony was extraordinary because it hadn't been done in church music before, and in medieval thought, anything new had to be founded on something old. This meant that any new compositions had to be based on a preexisting composition, such as church chants. This school of thought is known as Ars Antiqua.

Leonin and Perotin are often seen as representatives of this 'old school' mentality. Their work is seen as a bridge to the Ars Nova, or new school art, which would emerge late in the Medieval Period and lay the foundation for the musical transition to the Renaissance Period.


In order to achieve new music while adhering to the Church's strict music rules, both composers added additional vocal parts to what was previously a single line of church chant. Often times, the original chant was sung at an extremely slow pace, while a new, faster melody with more pitches was added at a higher pitch. This new type of multi-part chant was called organum.

Leonin used these techniques to write music with two vocal parts. This type of two-part organum is called organum duplum. Perotin also used these techniques, but went a step further and composed for three and sometimes four vocal parts. These are called, respectively, organum triplum and organum quadruplum.

Magnus Liber Organi

In fact, Leonin and Perotin were so good at writing organum that they wrote the first complete annual cycle of chants for the mass in two parts. The music was compiled as a book called the Magnus Liber Organi, or the 'Great Book of Organum.' Leonin wrote the original version, and later, Perotin edited and added new ideas afterward. By the end, it sounded something like this. It is said that other composers of the Notre Dame school also contributed, but Leonin and Perotin are the only ones credited by name.


Another important contribution from the Notre Dame composers was a sense of rhythm. Originally, chant was written freely to fit the liturgical text, so pacing and pattern were not considered to be terribly important. However, since musical notation had not developed as quickly as the music itself, it became difficult to write the parts to accurately reflect the way the parts were integrated. So the composers adopted six rhythmic modes, which were fixed rhythmic patterns of long and short notes.

There were six different modes, each with a different combination of long and short notes. The modes allowed the notation to be representative of the singing. Each type of rhythmic note had a particular structure, much like it does today, so even if it still looks a bit squiggly to us, it at least had consistent coding, so they could easily be identified.

The ability to read the notation became increasingly important as organum developed, and many organum contained discants. The discant occurs when the upper singing parts move together with the same rhythmic mode, like this. In this example from Perotin's arrangement of Sederunt principes, the long, slow original chant is at the bottom, while the duplum, triplum and quadruplum parts above it sing higher notes in the same rhythmic mode. So while the three higher parts have different pitches, their rhythms are the same.

Lesson Summary

In the short span of roughly 150 years, the Notre Dame school composers made some significant advancements in music. The strict rules of the Ars Antiqua required them to relate new musical ideas, such as polyphony, to the simple, traditional church chants sung in unison. The new style of multi-part chant called organum incorporated two, three and four part singing, along with new rhythmic ideas.

The two masters most associated with this style and time period are Leonin and Perotin, both of whom contributed to the yearlong church songbook called the Magnus Liber Organi. Their ideas paved the way for expansion of melodic and rhythmic ideas, which were to come in the Renaissance Period.

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