This relief depicts the celebration of the Christian Sacrifice of the Mass. In the centre, behind the altar, stands the priest, facing the faithful, before the implements of the Mass: chalice, paten and liturgical books. The schola, or choir of spiritual singers, forms the relief ’s foreground. Standing behind the priest, and beneath a ciborium crowned by angels, are the deacons who assist him. This ivory relief was produced in the ninth century. Later, in the fourteenth century, it was integrated into the cover of an evangelarium—a compilation of the sections of the Gospel read during the Mass. This reuse is not simply an indication that the carving was highly appreciated; the depiction also perfectly matches the content of the book.

The half-length figures of the Apostles painted on a gold ground flanking the ivory plate bear a direct relationship to the carving. They are turned inwards, towards the relief and the depression above it with the countenance of Christ, and thereby bear witness, as it were, to he sacrifice of Christ recapitulated in the Mass.

The carver is unknown. His designation derives from an ivory tablet depicting St Gregory in the possession of the Kunsthistorisches Museum in Vienna. Nor do we know who commissioned the work. The donor of the manuscript, on the other hand, is known to have been Balduin of Luxembourg (1285–1354), archbishop and elector of Trier and Mainz. It is not known why he donated the book, or for what location. In 1450, however, it is documented as being in St Bartholomäus in Frankfurt, the coronation church of the German kings and emperors. Perhaps Balduin—as elector one of those who chose the German emperor—had the manuscript made for the coronation Mass in Frankfurt.