Ambrose of Milan

But of what creature can it be said that it fills all things, as is written of the Holy Spirit: "I will pour My Spirit upon all flesh." This cannot be said of an Angel. Lastly, Gabriel himself, when sent to Mary, said: "Hail, full of grace," plainly declaring the grace of the Spirit which was in her, because the Holy Spirit had come upon her, and she was about to have her womb full of grace with the heavenly Word.