Agnus Dei (Barber) Agnus Dei (Barber) Agnus Dei (Lamb of God) is a choral composition in one movement by Samuel Barber, his own arrangement of his "Adagio for Strings" (1936). In 1967, he set the Latin words of the liturgical Agnus Dei, a part of the Mass, for mixed chorus with optional organ or piano accompaniment. The music, in B-flat minor, has a duration of about eight minutes. Barber's "Adagio for Strings" began as the second movement of his String Quartet, Op. 11, composed in 1936. At the request of Arturo Toscanini, he arranged it for string orchestra, and in January 1938 sent
Agnus Dei (liturgy) the Roman Missal, § 83, states: "The supplication "Agnus Dei", is, as a rule, sung by the choir or cantor with the congregation responding; or it is, at least, recited aloud. This invocation accompanies the fraction and, for this reason, may be repeated as many times as necessary until the rite has reached its conclusion, the last time ending with the words "dona nobis pacem" ('grant us peace')." In Tridentine Requiem Masses, the first two invocations ended with "dona eis requiem" (give them rest) instead of "miserere nobis", and the last with "dona eis requiem sempiternam" (give them rest eternal).