Bede the Venerable
Catena Aurea · Lukasevangelium 2
And there were in the same country shepherds abiding in the field, keeping watch over their flock by night. And, lo, the angel of the Lord came upon them, and the glory of the Lord shone round about them: and they were sore afraid. And the angel said unto them, Fear not: for, behold, I bring you good tidings of great joy, which shall be to all people. For unto you is born this day in the city of David a Saviour, which is Christ the Lord. And this shall be a sign unto you; Ye shall find the babe wrapped in swaddling clothes, lying in a manger.
(Home. ubi sup.) For in a mystery, those shepherds, and their flocks, signify all teachers and guides of faithful souls. The night in which they were keeping watch over their flocks, indicates the dangerous temptations from which they never cease to keep themselves, and those placed under their care. Well also at the birth of our Lord do shepherds watch over their flocks; for He was born who says, I am the good Shepherd: (John 10:11, 16.) but the time also was at hand in which the same Shepherd was to recal His scattered sheep to the pastures of life.