The Missal describes the Feast Day of the birth of Christ:
During Christmastide, the liturgy shows us the Messias as the Son of God, clothed with humanity, glorified by the humble surprised shepherds, and adored by the Magi from the East. Let us fall down before the Child and bless God, for the birth of Jesus is the beginning of our Redemption through grace to the supernatural life.
Christmas is the only day of the year other than Easter which keeps the old custom of celebrating its Feast at midnight. At this hour we are called to mind that Mary in her spotless virginity gave to the world its Saviour. In the midst of darkness, the Light was born. Therefore the Church celebrates Christmas on December 25, the time of the year when the days begin to lengthen.
The custom of having three Masses originated in Jerusalem. A Mass was said in Bethlehem at a very early hour in the morning. Later a second Mass was celebrated in the Church of the Resurrection in Jerusalem. About Midday a third Mass was celebrated. Each of the three Masses has its identifying characteristic. The Midnight Mass celebrates particularly the birth of Jesus, the Mass at dawn commemorates the adoration of the shepherds, the daytime Mass commemorates the eternal generation of the Word and the dignity of the Son of God.
Father Weiser tells us that The first Mass originally was connected with the vigil service at the chapel of the manger in the church of St Mary Major in Rome. There Pope Sixtus III (440 AD) had erected an oratory with a manger, which was considered a faithful replica of the crib at Bethlehem.
The reason for the first Mass being said at Midnight, he says, is because of the traditional belief that Christ was born at that hour. He observes that “[t]here is of course, no historical evidence to uphold this pious belief, which has its source in the following text from the Book of Wisdom (18, 14-15):
‘For while all things were in quiet silence, and the night was in the midst of her course, Thy almighty word leapt down from the heaven from Thy royal throne, as a fierce conqueror into the midst of the land of destruction.’
A beautiful Latin hymn of the fourth century, ‘Quando noctis medium’ expresses this common belief in Our Lord’s birth at midnight:’
“When the midnight, dark and still,
Wrapped in silence vale and hill:
God the Son, through Virgin’s birth,
Following the Father’s will,
Started life as Man on earth.'”
The Roman Missal provides that, “Whereas Advent is the season of the ‘absence of Jesus,’ Christmastide is a season of great joy in our possession of the Saviour.
During the season of advent we longed for the coming of Christ. In Christmastide we experience the joy of His coming into the world. The Church is full of the Mystery of the Incarnation of Christ, Jesus as God, begotten of the substance of the Father before all the ages and born of the substance of His Mother in the world, is given to us. ‘And His name shall be called the Angel of Good Counsel.’
By the union of our souls with Jesus born to human life, we are born to the divine life. ‘As many as received Him, He gave them power to be made the Sons of God.’ (St John)
In the birth of Jesus we learn to know God as His Father.”
(Source: Francis X Weiser, “A Handbook of Christian Feasts and Customs”, Harcourt, Brace and Company)
Image: The Nativity, Giotto : https://erinsweeneydesign.com/…/the-meaning-of…/