Luke 2:12

And this shall be the sign unto you (by which you may know this child from others recently born), ye shall find the babe wrapped in swaddling clothes lying in a manger. For other children born at that time were in houses and in beds, only Christ was in a manger in a stable. Hence it appears that this manger was commonly known to every one, unless we suppose, as Toletus would have it, that the angel pointed out to the shepherds with his finger, or by an inward inspiration, the cave where the manger was. The angel gives this sign that the shepherds may not suppose, according to the Jewish notion, that their Messiah, as King of the Jews, was to be sought in the royal palace of Herod or in any place of the same kind. For this was Christ's first Advent the Advent of Humility, as His second Advent, to judge the world, will be one of Majesty. The sign, then, of the Word Incarnate and straitened is the lowliness of the swaddling bands and the manger. As S. Bernard says, Serm. 1, "On the Nativity," "What more unworthy, what more detestable, what more severely punishable than that, seeing the God of Heaven become a little child, man should of his own free will set himself in opposition to magnify himself upon the earth? It is a trait of intolerable insolence that, where His Majesty has effaced Itself, a poor worm should be puffed up and swollen with pride."