Bernardino Pinturicchio, Adoration of the Christ Child with St. Jerome (in Sta Maria del Popolo)
What St Luke wrote in the Gospel about the birth of the Lord Jesus has been translated into countless songs and works of literature; these make up the rich tradition inspired by Christmas. We bring this tradition with us when we come to Midnight Mass, also called the “Mass of the Shepherds”. At this hour, Bishops and priests throughout the world join me, the Bishop of Rome, in celebrating this Mass. In every place liturgical and extra-liturgical songs are proclaiming the joy of the Lord’s birth. The angel says: Be not afraid, rejoice! The birth of a human being is always a source of great rejoicing (cf. Jn 16:21). What great joy then must the birth of the God-Man bring!
~Pope St. John Paul II, Homily for Midnight Mass, 1996
I particularly like this homily because he uses a Polish Christmas carol throughout -- and I remember him spontaneously singing what I think is this same carol to us at the Mass in Central Park in New York on the feast of the Holy Rosary a year earlier. He had a wonderful voice and so evidently enjoyed being with us.