God the Father gave his only Son to the world only through Mary. Whatever desires the patriarchs may have cherished, whatever entreaties the prophets and saints of the Old Law may have made for four thousand years to obtain that treasure, it was Mary alone who merited it and found grace before God by the power of her prayers and the perfection of her virtues. “The world being unworthy,” said St. Augustine, “to receive the Son of God directly from the hands of the Father, he gave his Son to Mary for the world to receive him from her.”
The Son of God became man for our salvation but only in Mary and through Mary.
God the Holy Spirit formed Jesus Christ in Mary but only after having asked her consent through one of the chief ministers of his court.
God the Father imparted to Mary his fruitfulness as far as a mere creature was capable of receiving it, to enable her to bring forth his Son and all the members of his mystical body.
God the Son came down into her virginal womb as a new Adam into his earthly paradise, to take his delight there and produce hidden wonders of grace.
God-made-man found freedom in imprisoning himself in her womb. He displayed power in allowing himself to be borne by this young maiden. He found his glory and that of his Father in hiding his splendors from all creatures here below and revealing them only to Mary. He glorified his independence and his majesty in depending upon this lovable virgin in his conception, his birth, his presentation in the temple, and in the thirty years of his hidden life. Even at his death she had to be present so that he might be united with her in one sacrifice and be immolated with her consent to the eternal Father, just as formerly Isaac was offered in sacrifice by Abraham when he accepted the will of God. It was Mary who nursed him, fed him, cared for him, reared him, and sacrificed him for us.
St. Louis Marie de Montfort, True Devotion to the Blessed Virgin, nn. 16-18.