Mary, Queen of Virgins, will be given this new song to sing which, in the Kingdom, will be given to virgins only (Rev 14: 3-4). She will sing it with all the others, or rather will be the first one to sing it -- how could one doubt it?
I even think that, in addition to this song reserved for virgins only and which she will carry out in chorus with the all the others (as I have just said), Mary will delight the city of God by an even sweeter and more exquisite song, of which no other virgin will be found worthy to modulate or imitate the harmonious chords; it will be reserved for the virgin who, alone, had the honor to be a mother, and the Mother of God.
If she glorifies herself with her maternity, it is not in herself, but in the one she gave birth to: God -- in truth He is God the one whom she brought to the light -- who took care on earth to provide His mother with unequalled grace, and this grace enabled Him to ineffably unite conception and virginity, childbirth and integrity, will endow His mother in Heaven with an unsurpassed glory.
Granted, the only birth worthy of God was to be born of a virgin and the only childbirth worthy of a virgin was to give birth to God. Thus the Creator of men, who to become man wished to be born from man, had to choose or rather to create for Himself, from among all creatures, a mother gifted with qualities that would be worthy of Him, and to recognize in her the ability to please Him.
To that end He willed her a virgin, in order to be born immaculate from an immaculate one, since He was coming to purify the stains of all men. Likewise He willed her humble, to be born of her meek and humble of heart, since He was coming to give a perfect and salutary example of these two virtues by His life.
He thus made it possible for the virgin to give birth, after having inspired her to make a vow of virginity and granting her the privilege of staying humble.
Otherwise, how could the angel, thereafter, greet her as "full of grace"; if there was in her any good which did not proceed from grace?