28 And the angel being come in, said unto her: Hail, full of grace, the Lord is with thee: blessed art thou among women. 29 Who having heard, was troubled at his saying, and thought with herself what manner of salutation this should be.
Jerome: It is well said, Full of grace, for to others, grace comes in part; into Mary at once the fullness of grace wholly infused itself. She truly is full of grace through whom has been poured forth upon every creature the abundant rain of the Holy Spirit.
Ambrose: Mark the Virgin by her bashfulness, for she was afraid, as it follows; And when she heard, she was troubled. It is the habit of virgins to tremble, and to be ever afraid at the presence of man, and to be shy when he addresses her.
Greek Expositor: The Evangelist ascribes her agitation not to the vision, but to the things told her, saying, she was troubled at his words. Now observe both the modesty and wisdom of the Virgin; the soul, and at the same time the voice. When she heard the joyful words, she pondered them in her mind, and neither openly resisted through unbelief, nor forthwith lightly complied; avoiding equally the inconstancy of Eve, and the insensibility of Zacharias. Hence it is said, And she cast in her mind what manner of salutation this was, it is not said conception for as yet she knew not the vastness of the mystery.
Ambrose: She wondered also at the new form of blessing, unheard of before, reserved for Mary alone.
Origen: If Mary had known that similar words had been addressed to others, such a salutation would never have appeared to her so strange and alarming.
Scripture from the Douay-Rheims Bible. Commentary from St. Thomas Aquinas, Catena Aurea, Vol. III (London: Rivington, 1843).