Rorate Caeli

FIAT - Be it done: The greatest Word of the Blessed Virgin Mary

Alfons Maria Mucha
Virgin of the Lilies (1902-1905)
The Virgin did not say to the Angel, "I will do what you tell me," but instead said, fiat. be it done, which God our Lord used when he created this world, saying, fiat lux (let there be light).

Because the Virgin understood that the Incarnation was the work of the omnipotence of God as much as the Creation of the world, and that with one fiat of his omnipotence it was to be done, without there being from her part any merit of such a glorious thing. Even though she also accepted it by saying fiat, as one who says: even though my consent was not required, since I declared myself the handmaid of the Lord, and he can do to his servant whatever he wants, still fiat, let it be done, because I will love whatever he wants. In which event one can see the sovereign obedience and resignation of the Virgin, founded in her knowledge of her nothingness, offering up herself so as to not resist the fiat of God. ...

 I give Thee thanks, most Blessed Virgin, for this generous oblation that Thou makes with such great magnanimity of heart. May the Angels of Heaven praise Thee, and the righteous of the earth, and those who were waiting for it in the Bosom of Abraham. And because to all men was granted a portion of thy consent, beseech thy Son to grant me the resignation so as to not resist to whatever work He may send me, but instead that I may say fiat to all things. God is my Lord: whatsoever is good is his eyes, be it done unto me, his servant.
Venerable Luis de la Puente
Meditations on the Mysteries of Our Holy Faith

[Compilation of the meditations relating to the Blessed Virgin, 1829]