O Magnum Mysterium is a responsorial chant from the Matins of Christmas.
The image of the oxen and donkey next to the crib is found in Isaiah (Isa. 1.3) and is traditionally related to the nativity scene at the birth of Jesus in Luke 2. Luke (Lk 2.7) does not mention animals, but a manger. In the apocryphal Gospel of Pseudo-Matthew, both animals are specifically named. The image continued to spread from the 13th century onwards when it was included in the Golden Legend. It became the most popular symbol for the mystery of the self-abasement of God in his Incarnation. (Phil 2,6-7).
The second part of the responsory relates to the words with which Elizabeth welcomes Mary, mother of Jesus on her visitation (Lk 1.42-43).
A great number of composers have reworked the chant into a contemporary setting; the settings by Byrd, Victoria,Gombert, Gabrieli,Palestrina,Poulenc, Judith Bingham, Harbison, La Rocca, Mäntyjärvi, Pierre Villette, Morales, Lauridsen,Busto, Louie, Maw, David Conte, Miskinis, Antognini, Da Rold, Gjeilo, are notable.