15 And it came to pass, after the angels departed from them into heaven, the shepherds said one to another: Let us go over to Bethlehem, and let us see this word that is come to pass, which the Lord hath shewed to us. 16 And they came with haste; and they found Mary and Joseph, and the infant lying in the manger. 17 And seeing, they understood of the word that had been spoken to them concerning this child. 18 And all that heard, wondered; and at those things that were told them by the shepherds.
Greek Expositor: Beholding with hidden faith indeed the happy events which had been told them, and not content with marveling at the reality of those things which at the very first they saw and embraced when the Angel told them, they began to relate them not only to Mary and Joseph, but to the others also (and what is more they impressed them on their minds,) as it follows, And all who heard it marveled.
Gloss: Not only do they marvel at the mystery of the incarnation, but also at so wonderful an attestation of the shepherds, men who could not have devised these unheard of things, but were with simple eloquence proclaiming the truth.
19 But Mary kept all these words, pondering them in her heart.
Ambrose: Esteem not the words of the shepherds as mean and despicable For from the shepherds Mary increases her faith, as it follows: Mary kept all these sayings, and pondered them in her heart. Let us learn the chastity of the sacred Virgin in all things, who no less chaste in her words than in her body, gathered up in her heart the materials of faith.
Bede: For keeping the laws of virgin modesty, she who had known the secrets of Christ would divulge them to no one, but comparing what she had read in prophecy with what she now acknowledged to have taken place, she did not utter them with the mouth, but preserved them shut up in her heart.
Scripture from the Douay-Rheims Bible. Commentary from St. Thomas Aquinas, Catena Aurea, Vol. III (London: Rivington, 1843).