Definitions for Medieval Christian Liturgy
Agnus dei


According to the Liber pontificalis Pope Sergius I (687- 701) introduced the Agnus dei into the Roman Mass. It was at that time a chant sung by both the clergy and the laity to accompany the breaking of the bread after the eucharistic prayer and before the communion. The text was comprised of one simple petition: Agnus dei qui tollis peccata mundi, miserere nobis (Lamb of God who takes away the sins of the world, have mercy on us). The assembly continued to sing the phrase until the pope gave the sign that the fraction was completed.

Since Christians understood Jesus to be the cosmic Passover lamb slaughtered to save them from sin and death, and since they interpreted the unleavened Passover bread as his body sacrificed for the world, their singing of the Agnus dei while the very bread they believed to be his body was torn apart bore particularly strong christological significance: the bread was the Lamb of God being sacrificed that they might partake of it.

During the Carolingian period two practices arose that changed the shape of the Agnus dei: the custom of using small pieces of unleavened bread and the infrequent distribution of communion to all present. These changes greatly decreased the time necessary for both the fraction and the communion. The Agnus dei was reduced to a tripartite repetition of the supplication. In several of the early sources, though, the second petition was changed to reflect the language of the Gloria in excelsis:

Agnus dei qui tollis peccata mundi, miserere nobis.
Agnus dei qui sedes ad dexteram patris, miserere nobis.
Agnus dei qui tollis peccata mundi, miserere nobis.

Lamb of God, who takes away the sins of the world, have mercy on us.
Lamb of God, who sits at the right hand of the father, have mercy on us.
Lamb of God, who takes away the sins of the world, have mercy on us.

Around the year 1000 the Agnus dei assumed the textual form that eventually became standard throughout the Roman rite:

Agnus dei qui tollis peccata mundi, miserere nobis.
Agnus dei qui tollis peccata mundi, miserere nobis.
Agnus dei qui tollis peccata mundi, dona nobis pacem. (Lamb of God....grant us peace.)

Sources

Further Readings

David Hiley, Western Plainchant: A Handbook, (Oxford, 1993): 165-168.

Peter Wagner, Introduction to the Gregorian Melodies: A Handbook of Plainsong, trans. Agnes Orme and E.G.P. Wyatt, 2nd edition, (New York, 1986): 101-102.

Joseph A. Jungmann, The Mass of the Roman Rite: Its Origins and Development, trans. Francis A. Brunner, vol. 1, (New York, 1950): 303-311; 332-340.

Richard L. Crocker, Agnus dei, The New Grove Dictionary of Music and Musicians, vol. 1, (1980): 157-158.