Agnus Dei (liturgy) Agnus Dei (liturgy) In the Mass of the Roman Rite and also in the Eucharist of the Anglican Communion, the Lutheran Church, and the Western Rite of the Orthodox Church the Agnus Dei is the invocation to the Lamb of God sung or recited during the fraction of the Host. The Syrian custom of a chant addressed to the Lamb of God was introduced into the Roman Rite Mass by Pope Sergius I (687–701) in the context of his rejection of the Council of Trullo (692), which was well received in the Byzantine East and called the Quinisext Council, but
Agnus Dei (Barber) for a solo soprano. Soprano and alto are divided in two parts, tenor and bass occasionally even in three. The music is dominated by a melody, first presented by the soprano, which begins on a long note and then undulates in even rhythm and diatonic steps, a melisma of two measures on the words "Agnus Dei". The other voices enter half a measure later on a chord, move to a different chord in measure 2 and sustain it throughout the measure, while the soprano holds its first note through measure one and moves only after the supporting chord has changed