An angel appeared to Joseph in his sleep, as to a man who was readily disposed to believe; to the shepherds he appears visibly… But an angel did not go to Jerusalem, nor seek out the Scribes and Pharisees; for they were corrupted, and tormented with envy. But the shepherds were sincere of heart, observing the ancient teaching of the patriarchs and of Moses. For blamelessness is one of the paths that leads to wisdom.
St. John Chrysostom
"The Sunday Sermons of the Ancient Fathers"