ABSTRACT
From an abundantly cited passage in the treatise of the so-called Anonymus IV we know that Magister Perotinus abbreviated the Magnus Liber, composed by his predecessor Leoninus. The rhythmic content of all three phrases is the same, except for one note in the third phrase, which prevents unity from turning into monotony. The Clausulae are usually said to have preceded the Tripla and Quadrupla, the latter representing Perotin's crowning achievement, which he would not have been able to accomplish without prior extensive practice in two-part composition The approximate dates of the Quadrupla are known with fair certainty, because four-part composition is first mentioned at Notre-Dame in two episcopal edicts of 1198 and 1199, which concern precisely those festivals for which these compositions are appropriate. Perotinus Magnus activity in Paris coincided with the erection of Notre-Dame. Both the cathedral and the oeuvre of Magister Perotinus are climactic monuments of the classic Gothic.
