Agnus Dei

The fifth and last item of the Ordinary of the Mass. Originally a part of the Litany, it was first introduced into the Roman Mass towards the end of the 7th century. It is not present in the Ambrosian rite. Its text is tripartite in structure, and its music in its simplest form consists of three statements of the same melody.

More complex plainsong settings exist and in the later Middle Ages numerous additional melodies were written. The Agnus Dei is naturally included in polyphonic settings of the Mass Ordinary, and in later settings of the same series of texts.