Leonardo Boff in his book “The Maternal Face of God” presents the
idea of a hypostatic union of the human and Divine in Mary akin to that in
Jesus, with the former involving the Holy Spirit like the latter involves the
Son.
Below are some thoughts elaborating on that idea.
The very beginning of the Bible affirms that at the start of creation, before God spoke creation into existence, “ve-ruach Elohim merachefet ‘al p’nei hamayim” (Gen. 1:2) – “and the breath of God fluttered over the face of the waters”. Note two things about this verse – ruach literally means “breath” and the word is feminine, as made clear by the feminine verb form “merachefet” (a bird-like fluttering used to poetically characterize the light breathing in and out of involuntary breath). So, before “speaking” creation into existence, before the “word” that is the formative principle of creation proceeds from God, God’s feminine “breath” was present, just as human breath precedes any human speech. Breath in humans is an involuntary and continuous activity, and without it, the human being will die – it is an essential activity. So to take the Bible’s description further, God’s feminine ruach must be regarded as essential to God, not a creation by God but an aspect of God. Going back to Gen. 1:2 and what follows, it is clear that the “ruach Elohim”, like breath in humans, not only precedes, but also is the actual source of God’s all-formative “word” (cf. also Ps. 33:6), just as human spoken words are derived entirely from breath driven through the vocal apparatus to create sound. Thus, the “breath” of God does and can exist without the “word” of God, but the “word” of God cannot exist without the “breath” of God.
The “breath” of God and “word” of God are not only involved in creation (cf. Gen. 1:2-31; Job 33:4; Ps. 33:6), but are present in each creation (cf. Gen. 2:7, 6:17, 7:21-22; Eccles. 12:7; Deut. 8:3; Ps. 119:89). So, what about an “incarnation” of the “word” or “breath” of God, when they are already so to speak “incarnate”? One can understand this as follows: normally, the presence of God’s “word” and “breath” is not manifest to that particular creation itself let alone to others perceiving that creation, but when speaking of an “incarnation” of the “breath” or the “word” of God, this would mean that this presence is manifest to that creation and, through it, to others. Now, if God's “word” is “incarnate” (manifest to and through), then God's “breath” also must be “incarnate” since, as discussed above, no “word” can exist without the “breath”, its source and substance. And since the “word” is not itself the “breath” but stands in relation to the “breath” as its product, thus, the “incarnate” “word” does not itself “incarnate” the “breath”. Therefore, the “incarnate” “breath” is another, and, as the “breath”, being feminine (cf. Gen. 1:2, Job 33:4, etc.), is “mother” to the “word”, so too the “incarnate” “breath” must be the physical mother of the “incarnate” “word”. So, if in Jesus, the “word” is manifest to him and through him, then in Mary, the “breath” is manifest to her and through her.
Mary's conception of the “incarnate” “word” from the Holy Spirit (Divine “breath”) is not an impregnation by a masculine principle. Matthew 1:18 and 1:20 do not state this in the Greek, but merely that Mary is with child from the Holy Spirit and that what is conceived in her is from the Holy Spirit, by which one can understand that the child himself, as God’s “word”, originates from God’s “breath”, and nothing more. Luke 1:35 also does not indicate such a thing, but refers to the Holy Spirit coming upon her and the power of the Most High overshadowing her. By Matthew and Luke, we can understand that since the “breath” is the source and very substance of the “word” at God's will in Divine “speech”, the “incarnation” of the “word” in Mary is through the manifest presence (“incarnation”) of its source and substance “breath” in her (the Holy Spirit coming upon her) at the will of God (power of the Most High overshadowing her).
Interestingly, the essential non-voluntary relation of the “breath” to God but voluntary relation of the “breath” produced “word” to God would suggest a difference in the “incarnations” in Mary and Jesus. Mary would “incarnate” what is an essential aspect of God, while Jesus would “incarnate” what is a voluntary aspect assumed by God through the “breath”. This difference therefore contradicts “orthodox” Trinitarian theology, and puts Mary in a very special role indeed, making Mary worthy of reverence quite independently of her relationship to Jesus.