“Is there not a remarkable similarity between the marriage of nature with grace and the nuptials of Mary, the Virgin Mother, with the Holy Spirit? No resemblance is more deeply grounded than this, and nothing is more significant for grasping the grandeur of Christianity. The Virgin Mother, as the Church says, poured forth the eternal Light into the world; she bore the Son of God in His human nature and conceived Him in her womb. Through grace the Son of God is to be born again in human nature, not in physical unity of person, but in a moral, personal union, by a real image of His divine light and a real sharing of His divine life. The hypostatic union is the ideal, as well as the principle and end of the union by grace. It is the principle, because by it the Godhead is brought close to all mankind in inseparable union; the fullness of divinity was united with one individual of human nature, to be communicated to all others by participation. It is the end, because the true God-man must be the Head and King of all men who have been made to share in the divine nature through Him, and they must all be associated with Him for the greater glorification of His majesty.
The manner in which the divine nature in the person of the Word was wedded with human nature in the womb of the Virgin Mother corresponds in all details with the manner in which God wishes to be united in grace with nature as it exists in every man. Human nature could have been imparted to the Son of God by creation. In that case no mother would have been needed. But because He wished to be born in human nature, the Holy Spirit had to be joined in a nuptial union with a human mother. She had to cooperate with the Holy Spirit in this work; God could not form a man who was to be born into the human race without her, and she could not give birth to the Godman without God. She was the immaculate soil that the Holy Spirit was to overshadow like a cloud and to make fruitful with the dew of His power.
From eternity He had chosen her to be His bride, and awaited with ardent love the time when He could give Himself to her. And she, on her side, illuminated and incited by His grace, yearned as no other creature could for the infinitely exalted union of God with mankind. But this yearning was joined with deepest humility, for she was well aware of the infinite distance between God and herself; she knew that she could not merit that stupendous favor, and she did not consider herself worthy to see the sublime mystery fulfilled in her.
Then the Holy Spirit sent word to her through an angel and invited her to be His spouse. Although her consent did not decide God to decree the mystery, God was pleased to await her consent, that the nuptials might be celebrated with free love on her part, too. ‘Behold the handmaid of the Lord,’ she said, ‘be it done to me according to thy word’ (Luke 1:38). As an obedient, humble maid, she assented to the word that conveyed her Lord’s request to her to become His mother. With the same sense of lowliness, the same consciousness of her nothingness with which she regarded herself as unqualified and unworthy of so august a union with supreme Goodness, she humbly subjected herself to God’s precious love, and yielded herself to be raised to the highest pinnacle of dignity, to cooperate with God’s greatest work.
Thus is accomplished the chaste marriage of the purest and most responsive creature with the all-pure and all-holy God. The dew and the power of the Holy Spirit flow down upon this receptive soil, to impart to it a divine fruitfulness and to cause the heavenly blossom to spring forth from the root of Jesse. The divine light in undiminished fullness falls on her as on an untarnished mirror, to be born by her and to be poured out by her into all the world.
Mary was a virgin before the marriage, because she had received no other seed, had taken to herself no alien light. She is a virgin in the union, because she suffers no hurt in her own life by receiving the divine seed, but on the contrary flowers forth into a higher life; she is not stained by the heavenly light, but is purified and transfigured with celestial beauty. She remains a virgin after the nuptial union, because she, having born the most perfect fruit and having been flooded with the very source of light, nevermore can or may receive another seed, another light.
Can there be a greater similarity, can a more perfect parallel be drawn out, than between the marriage of the Virgin with the Holy Spirit and that of nature and grace? The resemblance is so striking and clear in all details that we do not have to pursue the comparison in its individual traits. On both sides the analogy is evident: the height and depth, the infinite and the finite, heaven and earth are joined in a most astonishing and intimate union. Both mysteries alike are sublime and wonderful: ‘Which is more tremendous, which is more amazing: that God gives Himself to earth, or that He gives you to heaven; that He Himself enters into association with flesh, or that He grants you fellowship with divinity?” (St. Peter Chrysologus) The two mysteries are closely related; because of this relationship, both are the starting point, the center, and the goal of the entire supernatural economy of Christianity.”
-Matthias Scheeben in Nature and Grace.