Choral Alleluya V. Posui Adiutorum is a three-part organum, which is attributed to the medieval French composer Perotinus (fl c.1200), who is also known as Pérotin. Organa were the earliest form of vocal polyphony, dating back to the 9th century. The Parisian organa, of which Alleluya V. Posui Adiutorum is an example, was the high point of organa composition before giving way to the composition of motets. They were used in both the Offices (small services held throughout the day) and the Ordinary of the Mass (The part of the mass that could use changeable texts). Alleluya V. Posui Adiutorum forms the alleluya for the Mass of the common of the Confessor Bishop. As an Alleluya, the text of this organum consists of the word "Alleluya", followed by a verse which reads "Posui adiutorium super potentem et exaltavi electum" which is followed by plainsong. ~ David Cashman, All Music Guide
