Corpus of Latin Ecclesiastical Writers, Vol. LXII: Ambrose's Exposition of Psalm 118

he did not fear the enemies; but his servant feared, who did not see the angels. By the grace of God, at the voice of the prophet, his eyes were opened; he saw the armies of angels and believed them to be present, whom he had previously thought absent because he could not see them. Read the prophet, therefore, so that you may see; read, so that he may open your eyes, lest a hostile legion terrify you and you believe yourself to be besieged when you are free, for you are protected by spiritual hosts if you do not abandon the 2 prophet. When the prophet speaks to you, because God said: I fill heaven and earth, when the prophet says to you: Because there are more with us, because angels are in our circuit, raise the eyes of your mind and you will see not only the angels, but also God, who says to you: Open to me, my sister, my neighbor. He knocks at the door even when you are asleep; yet, if you awake when aroused, or if you open the door of your heart when called, He will enter. But if you flee from prophetic reading, if you do not read at home, if you refuse to hear it in church, do you not—like that man who, with averted gaze, closes his eyes lest he see what he could see, or like many in their fury who have laid hands upon their own eyes—likewise first turn away, hiding yourself with 3 a feigned ignorance rather than a stark refusal? For when you come to church and profess yourself a Christian, you seem sound, you open your eyes with which you might see; but while you pretend not to hear what is read, you close them lest you see for your own benefit. Even if you seem to see others, you cast certain hands of treachery and intemperance upon the eyes of your soul and bring blindness upon your own heart, which is more serious, because it is voluntary, so that seeing you do not see, and hearing you do not hear.

12. You think yourself alone when you commit fornication, and you do not remember that the eyes of the Lord see the whole world? Do you not hear Him saying:

References: Jer. 23:24; 2 Kings 6:16; Cant. 5:2; cf. Matt. 13:13