Many organa were composed for services devoted to the Virgin Mary, the patron saint of Notre Dame Cathedral (Notre Dame means “Our Lady”). Our example is added to a lengthy chant for the Mass, “Alleluia. Diffusa est gratia.” The music was probably written by Pérotin, though we cannot be certain.

At first the chant is sung — in the usual monophonic way:

The whole chant is much longer, but this opening “Alleluia” section is the most important part — it comes back twice before the chant is over — and the most beautiful. The exclamation alleluia often calls for especially long melismas (see page 48), passages of pure, joyful vocalism. The melisma on the syllable -lu seems to rouse the melody, which then springs up still higher in phrase 2; then this melodic climax is balanced by a quiet, sinking “answer” in phrases 3 and 4. This alleluia is a beautiful example of the characteristics of tunes discussed in Unit I (see page 26).

Then the organum starts. The voices begin with a strange, static harmony, which comes to life when the upper voices start to intertwine in quick, triple-time rhythms of the kind shown in the margin. They are singing long melismas on the syllables Dif- fu- sa, and so on.

Underneath, the lowest voice is singing the rest of the chant — but no longer in the characteristic free rhythm of Gregorian chanting. Sometimes the chant plods along in a stiff, regular rhythm (as at 1:21). Sometimes it is slowed down enormously (at 0:37, 1:07, and 1:33); at these points the chant is unrecognizable — it has been reduced to a series of lengthy drones. The plainchant has become a sort of musical scaffolding for the added counterpoints, a constructive element supporting the ecstatic upper-voice melodies, which are the main focus of interest in this music.

Our recording omits part of this lengthy organum (the section indicated by italics). It ends with a huge melisma on de- and a sort of shudder on the final syllable -us. Then plain chanting is resumed, as the original “Alleluia” music returns twice, first with new words, in aeternum, and then with its original alleluia — a peaceful close.