O Magnum Mysterium is one of the greatest texts for choral music from the Renais-sance to the present day but has some variations used by composers from Victoria to Poulenc. Gregg has chosen the version of the text that includes Dominum Jesum Christum and includes a final Alleluia instead of Amen. The image of the oxen and donkey next to the crib is found in Isaiah and is traditionally related to the nativity scene at the birth of Jesus in Luke 2. The image continued to spread from the 13th century onwards becoming the most popular symbol for the mystery. The second part of the responsory relates to the words with which Elizabeth welcomes Mary, mother of Jesus on her visitation. Gregg uses a mixture of notation styles in this piece with dissonant harmonies and instances of polytonal chords with a challenging piano part. The entire piece is based on the O Magnum Mysterium of Tomas Luis de Victoria. There is a wonderful "insider joke" on page 16 in the piano part at the beginnin