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. (Source: Yale.edu)
Agnus dei qui tollis peccata mundi, miserere nobis.
Agnus dei qui tollis peccata mundi, dona nobis pacem.
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, grant us peace.
I composed this short piece as a prayer for the deprived. Nowadays there is much suffering in our world caused by war and violence. The prayer is an invocation to the Holy Lamb to forgive us our sins and to use its divine powers to give us piece. The piece starts with a rather minimalistic outline of the theme. The prayer then intensifies culminating in a joyful middle part. It ends in a more solemn resignation.
I dedicated the piece to David Lamb. The score is uploaded together with this post as a PDF file.