Agnus Dei

AGNUS DEI. - Liturgical formula introduced into the Mass by Pope Sergius I, following an ancient Greek usage, with direct allusion to the expression of John the Baptist (Jn. 1:29). It was to be sung with the response: Miserere nobis, repeated several times during the solemn fraction of the consecrated bread. Since this solemnity in the 11th century was reduced to the celebrant alone, the chant was limited to three invocations, the third with the response: Dona nobis pacem. In requiem Masses, however, according to an older usage of the Ambrosian liturgy, Dona eis requiem is repeated, with the addition of sempiternam the third time in the Roman liturgy, and et locum indulgentiae cum sanctis tuis in gloria, in the Ambrosian liturgy. The same formula of the A. D. is already found almost identically in the Gloria in excelsis (v.), a hymn which, according to the Constitutiones Apostolorum (VIII, 13, 13), was to be said in a shorter form by the people immediately before Communion. From this usage was perhaps introduced into the Roman liturgy the Ecce A. D. etc., which is recited before distributing Communion to the faithful: a formula which, moreover, is found identically in the ancient liturgy of St. James. The same invocation of the A. D. is found already from the 7th century (Ordo of St. Armand) at the conclusion of the litanies, whether in the liturgy or privately.

Filippo Oppenheim