The image of the oxen and donkey next to the crib is found in Isaiah (Isa. 1.3) and is traditionaly 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).