A great
composer of the twelfth and thirteenth centuries: Pérotin or Perotinus might have lived about 1183-1238 in Paris, a member of the School of
Notre Dame (though identifying him biographically is hard). His works and those of his contemporary
Leonin expanded
monophony in
Gregorian chant into the new style of
polyphony. He was nicknamed the Great and the Master.
His characteristic mode was called organum, with one chant in tenor accompanied by higher voices (duplum, triplum, quadruplum) in quicker rhythms ringing changes on it. The most played work of his these days is the extraordinary Viderunt omnes for four voices, whose five syllables take several minutes to sing. One voice maintains the vi- and others move around it, with a bouncy vi- vi- vi- vi- vi- vi- for about forty-five seconds, then they move onto the syllable -de-. It was composed for the Gradual for Christmas.
Anyone who likes the thought of something slow and hypnotic between Hildegard of Bingen and Philip Glass should listen to Perotin.
(Much later) Having just heard Viderunt omnes on the radio again, I think I caught that it was first performed in Notre Dame Cathedral on Christmas Day 1198.