Augustine of Hippo : So there is a forehead of the inner self. That is where those people were marked, to save them from being wiped out. Because even if they did not put right the sins that were committed among them, at least they were pained by them, and by their very pain they set themselves apart; while set apart for God, they were mixed together in the eyes of people. They are marked with a sign in secret; they escape harm in public. The destroyer is sent next and is told, "Go, destroy, do not spare young, old, male, female; but do not go near those who have the sign on their foreheads." What a sure guarantee has been given you, my brothers and sisters, you among this people who are groaning and grieving over the wicked deeds committed in your midst and are not committing them! — SERMON 107:7 Jerome : And what follows: 'And begin from my sanctuary,' or as the Seventy have translated, 'begin from my saints,' which means the priests who served in the temple and worshipped idols; or those who were called holy due to their merit in the priesthood among the people, and who were the first to deserve punishment for the sins of the people. For it is time, as it is written in I Corinthians 7, that judgment begin from the house of God. — Commentary on Ezekiel