As the final sung item of the Mass ordinary, the Agnus Dei closes every complete Mass setting in the Western musical canon, from the anonymous masters of the medieval cycles through Palestrina and Byrd to the concert Masses of the classical and romantic centuries, and composers have habitually saved a particular tenderness for it, the plea for mercy and peace inviting music of quiet rather than splendour.
The dona nobis pacem of Bach's Mass in B minor and the troubled, drum shadowed Agnus Dei of Beethoven's Missa solemnis, marked as a prayer for inner and outer peace, are only the most famous cases of the text drawing from composers a meditation on peace itself. The phrase also named a sacramental. From the medieval period until modern times, wax discs stamped with the image of the lamb, blessed by the pope and called Agnus Deis, were distributed and worn as objects of devotion, an extension of the liturgical image into the pockets of the faithful.
The Eastern liturgies have no equivalent chant at the fraction, but the same scriptural image stands even closer to the centre of their rite, for in Byzantine usage the portion of bread destined for consecration is itself called the Lamb, cut from the loaf with the Baptist's words, so that East and West carry the same verse into the eucharist by different doors.