20 And the shepherds returned, glorifying and praising God, for all the things they had heard and seen, as it was told unto them.
Athanasius: Every one rejoiced in the nativity of Christ, not with human feelings, as men are wont to rejoice when a son is born, but at the presence of Christ and the lustre of the Divine light. As it follows: And the shepherds returned, glorifying and praising God for every thing they had heard, etc.
Bede: Let us go indeed casting aside all fleshly lusts, with the whole desire of the mind even to the heavenly Bethlehem, (i.e. the house of the living bread,) that He whom they saw crying in the manger we may deserve to see reigning on the throne of His Father.
The shepherds did not hide in silence what they knew, because to this end have the Shepherds of the Church been ordained, that what they have learned in the Scriptures they might explain to their hearers.
Every one of us, even he who is supposed to live as a private person, exercises the office of shepherd, if, keeping together a multitude of good actions and pure thoughts, he strive to rule them with due moderation, to feed them with the food of the Scriptures, and to preserve them against the snares of the devil.
Scripture from the Douay-Rheims Bible. Commentary from St. Thomas Aquinas, Catena Aurea, Vol. III (London: Rivington, 1843).