Christmas

This silver star in the Grotto of the Nativity in Bethlehem marks
what is believed to be the exact spot where Christ was born. 

From the Great Commentary of Cornelius a Lapide on the Gospel of St. Luke:

There is a question as to what place was the first to receive Christ at His birth.  Barradius thinks it was the ground, that Christ might teach us humility.  Others think that Christ was received into the arms of His Mother, with exceeding joy -- for this would seem to be becoming for such a mother and such a son, and would be natural, and is gathered from what Luke immediately adds, "and wrapped Him in swaddling clothes."  Taking Him in her hands she adored Him, kneeling, and then kissed Him most sweetly, and wrapped Him in the clothes and bands.  Suarez thinks that Christ, as soon as He was born, was laid by angels in the arms of His most holy and loving Mother; S. Gregory of Nyssa implies the same.  This would be the place most becoming to Him, and most consonant to the wishes both of Son and Mother; and from thence she placed Him in the manger.

From St. Alphonsus Liguori, The Incarnation, Birth and Infancy of Jesus Christ:

But why did Mary, who had so earnestly desired the birth of this Son -- why did she, who loved Him so much, allow Him to lie and suffer on this hard bed, instead of keeping Him in her arms?  This is a mystery, says St. Thomas of Villanova: "Nor would she have laid Him in such a place, unless there had been some great mystery in it."  This great mystery has been explained by many in different ways, but the most pleasing explanation to me is that of St. Peter Damian: Jesus wished as soon as He was born to be placed on the straw, in order to teach us the mortification of our senses: "He laid down the law of martyrdom."  The world had been lost by sensual pleasures; through them had Adam and multitudes of his descendants till then been lost.  The Eternal Word came from heaven to teach us the love of suffering; and He began as a child to teach it to us by choosing for Himself the most acute sufferings that an infant can endure.  It was, therefore, He Himself Who inspired His Mother to cease from holding Him in her tender arms, and to replace Him on the hard bed, that He might feel the more cold of the cave and the pricking of this rough straw.

From St. Thomas Aquinas, Summa Theologica, III, Q. 35, Art. 7:

...Christ willed to be born in Bethlehem for two reasons.  First, because "He was made...of the seed of David according to the flesh," as it is written (Romans 1:3); to whom also was a special promise made concerning Christ; according to 2 Kings 23:1: "The man to whom it was appointed concerning the Christ of the God of Jacob...said."  Therefore He willed to be born at Bethlehem, where David was born, in order that by the very birthplace the promise made to David might be shown to be fulfilled.  The Evangelist points this out by saying: "Because He was of the house and of the family of David."  Secondly, because, as Gregory says (Hom. viii in Evang.): "Bethlehem is interpreted 'the house of bread.'  It is Christ Himself Who said, 'I am the living Bread which came down from heaven.'"

...According to a sermon in the Council of Ephesus...: "If He had chosen the great city of Rome, the change in the world would be ascribed to the influence of her citizens.  If He had been the son of the Emperor, His benefits would have been attributed to the latter's power.  But that we might acknowledge the work of God in the transformation of the whole earth, He chose a poor mother and a birthplace poorer still."

The Collect for Midnight Mass in the Traditional Latin Mass:

Deus, qui hanc sacratissimam noctem veri luminis fecisti illustratione clarescere : da, quæsu-mus, ut cujus lucis mysteria in terra cognovimus, ejus quoque gaudiis in cælo perfruamur.

O God, Who hast made this most sacred night to shine with the brightness of the true light : grant, we beseech Thee, that we who have known the mystery of His light upon earth, may enjoy also His happiness in heaven.