Organum

The earliest type of polyphony is called organum (plural: organa). First described in music theory treatises around 900 C.E., actual organum has survived in musical notation from around 1000. Early organum consists of a traditional plainchant melody to which a composer/singer/improviser has added another melody, sung at the same time with the same words.

The history of organum provides a fascinating record of growing artistic ambition and technical invention. A number of clear stages can be identified between about 1000 and 1200 C.E.:

Organum of these last, highly developed kinds flourished at the Cathedral of Notre Dame in Paris, which was built slowly over the period 1163–1345. The names of two composers of the so-called Notre Dame school are recorded: Master Léonin and his follower Pérotin (called “the Great”). Pérotin astonished thirteenth-century Paris by creating impressive organa for as many as four simultaneous melodies.

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Notre Dame Cathedral in Paris. Flying buttresses — the great medieval engineering feat that made such tall buildings possible — support the main structure (the nave). With its lofty front towers and its spire, Notre Dame seems to reach up to heaven itself. JRoss/RobertHarding.