Paris, ca. 1200.
In the scriptorium of the Library of the Cathedral of Notre Dame, the master of music looks with admiration at every neume of the Magnus Liber Organi. Therein is the most advanced music written since Franc maestros began developing – more than four hundred years – the art of polyphony, the singing of several voices to embellish the Office of the Mass.
Magister Perotinus Magnus studies the musical solutions which his predecessor, Magister Leoninus, had developed to balance the voices of the Gradual of the Mass and the Antifonario of the Office of the Hours.
Christmas is approaching and following it the day of St. Stephen, when pilgrims go to pray at the cathedral. Magister Perotinus works tirelessly, he wants to achieve a special moment in the Gradual of the Mass of St. Stephen, “Sederunt Principes et adversum loquebantur me …”, worthy of the first martyr of the Church.
He begins by separating the notes of the original Gregorian melody to obtain a deep, long, sound for each syllable of the text. A strong tenor to support a building of sound of four voices which he wants to build, an Organum Quadruplum … a feat. He adds, after the duplum and triplum melodies, and the last, the quadruplum.
To adjust for the rhythmic imbalances of the upper three voices, he ends by providing the same metrical foot constantly repeated for all, except in the sections of Clausula.
Arriving on the 26th of December, the pilgrims congregated and participated in the Morning Mass. The first rays of sunlight pass through the large rose window and tears the air inside the cathedral, and leave their coloured wake suspended in the air.
After the Epistle, the monks chant in unison and maintain the first syllable of Gradual Sederunt. Over that, the faithful listen with admiration at how the magnificent sound construction is every inch of the cathedral, all its space, wrapped in stained glass and stone.