ABSTRACT
The earliest direct reference to the Agnus Dei in the Mass is that found in Lucca, Biblioteca capitolare, Cod. 490, dating from the second half of the eighth century. This manuscript contains the first continuation of the Liber pontificalis after the "Cononian" redaction. Two categories of documents are important witnesses to the Agnus Dei in the later eighth century. These are the various Carolingian commentaries upon the Mass and manuscripts of the Gregorian sacramentary. As one can see from the incipits, the Agnus Dei verse was apparently intended to be sung three times, with the embellishing verses inserted between "mundi" and "miserere" in each petition. A final series of liturgical documents provides rather conclusive evidence that the Agnus Dei was a fixed part of the Roman Mass in the late eighth century. As demonstrated, the threefold Agnus Dei appear in sacramentaries in the ninth century, and becomes ever more frequent in the tenth and eleventh centuries.
