Gregory the Dialogist : And it should be noted that the prophet adds, saying: "And I opened my mouth and he fed me with that scroll." Another Prophet testifies that the mouth is in the heart, saying: "Deceitful lips in the heart, and with the heart they have spoken evil." Therefore we open our mouth when we prepare our understanding for the comprehension of the sacred word. Thus at the voice of the Lord the prophet opens his mouth, because at the breath of the Lord's command the desires of our heart yearn eagerly, so that they may receive something from the food of life. But nevertheless this very receiving is not within our own powers, unless he himself feeds us who commanded that he be eaten. For he is fed who cannot eat by himself. And because our weakness is not sufficient for grasping heavenly words, he himself feeds us, who measures out for us the portion of grain in due time, so that in the sacred word, while today we understand what yesterday we did not know, tomorrow also we may comprehend what today we do not know, and may be nourished by daily sustenance through the grace of divine dispensation. For Almighty God extends his hand to the mouth of our heart, as it were, as many times as he opens our understanding and places the food of sacred speech into our senses. Therefore he feeds us with the scroll, when by dispensing he opens to us the meaning of Sacred Scripture, and fills our thoughts with its sweetness. — Homilies on Ezekiel, Book 1, Homily 10 Jerome : (Verse 2.) And I opened my mouth, and he fed me with that scroll. And he said to me: Son of man. I, he said, opened my mouth, because I was told: Open your mouth, and eat. And, with my mouth open, the Lord bestowed food; so that the beginnings of the will are in us, and we attain the perfection of blessedness from the Lord. For it is not of the one willing, nor of the one running, but of the merciful God (Rom. IX, 16). However, both to will and to run is of our own free will. For He opened, they translated it as 'opened,' so that God may be understood, because He Himself both opened the mouth of the prophet and fed him. — Commentary on Ezekiel