Mary full by grace: It was given to her to be made holy.

     "To put it another way, how could the Angel have addressed her as full of grace if any, even a little, of these virtues [(si quidpiam, vel parum boni)] had been present in her already and not given to her by grace?  It was given to her to be made holy.  She, who was to conceive and give birth to the Holy of holies, was made holy in body by the gift of virginity and holy in mind by the gift of humility."

     St. Bernard of Clairvaux, Homily 2.1-2 in praise of the Virgin Mother, Office of readings for Tuesday of the Twentieth Week in Ordinary time, trans. (with the unjustified insertion of "It as given to her to be made holy") Universalis.  Trans. Liturgy of the hours:

     "Otherwise, how could the angel afterward pronounce her full of grace, if she had the slightest good quality which did not come from grace?  Thus she, who was to conceive and bring forth the holy of holies, must be sanctified physically and so she received the gift of virginity; that she might be sanctified spiritually, she received the gift of humility."

     "Alioquin quomodo Angelus eam in sequentibus gratia plenam pronuntiat, si quippiam vel parum boni, quod ex gratia non esset, habebat?
     "Ut igitur, quae Sanctum sanctorum conceptura erat pariter et paritura, sancta esset corpore, accepit donum virginitatis; ut esset et mente accepit et humilitatis."

Earlier (as trans., this time, more accurately in Universalis):

"The maker of mankind, if he was to be made man and destined to be born of man, would have to choose, to create [(debuit deligere, immo condere, would have to choose, no, rather, would have to fashion/produce/make/create)] a mother whom he knew to be worthy of him, who he knew would be pleasing to him."