Plato’s parable of the cave depicts the opposite movement to that which is occurring in the Virgin Birth. If one thinks of the cave as a womb, the entire struggle is to escape the cave/womb or set aside the material world and to achieve the singular source of light, the sun. Those imprisoned in the cave live in a world of shadows in which the only light is from a fire behind them, but the prisoner turned philosopher journeys toward the sun, representative of transcendent philosophical truth. As he journeys away from the cave/womb, or away from material reality, the philosopher draws closer to transcendent truth. With the birth of Christ, the equivalent of the singular light or the sole source of truth comes to inhabit the womb.
This not only challenges Greek thought, but as Mircea Eliade points out, since Plato sums up the pervasive religious and philosophical worldview, it challenges a predominant form of thought. There is an obvious impossibility posed in a virgin giving birth but this impossibility is a sign of the even more profound impossibility of God becoming human. This is on the order of the cave housing the sun, or the motherly and earthly encompassing and housing ultimate reality; an impossibility for the Greeks. Jesus born of a virgin is the bringing together of the human and divine in a way that was/is inconceivable for most of humanity.
Plato’s parable of the cave captures the fact that for most people in most of history ascent to the absolute (whether absolute truth, the place of God, etc.) is to shed the finite, material and relative. In the incarnation, signaled by the Virgin Birth all horizontal and vertical wires are crossed. It is more supernatural than the pagan portrayal of the coupling of the gods, as it is by sheer power and does not call upon the natural sex act. Justin Martyr (165 CE), refuting comparisons between the virgin birth and mythological couplings of the gods, writes of the Spirit which “when it came upon the virgin and overshadowed her, caused her to conceive, not by intercourse, but by power.” Ambrose of Milan (c. 339-97 CE) writes, “That a virgin should give birth is sign of no human, but of divine mystery.” Pagans could easily conceive of sex among the gods, but the virgin birth by-passes the sex act. However, it is also more natural and integrated with the human condition, in that Jesus will suffer, die, and experience the human predicament in its fullness, which is even more scandalous to the pagan mind. The Greek and pagan, but maybe just the human idea of God is inverted in the Virgin Birth, as the fully human and the fully divine are intermixed in the motherhood of Mary, her conception through God, and she gives birth to one who is fully God and fully human.
The point of Christianity, beginning with the Virgin Birth, is subversion of the pagan world, but by the same token Greek and pagan thought would continue to attack and attempt to subvert this basic Christian conception of the world. The Gnostics, Marcion (c. 85-c. 160 CE) and Valentinus (c. 100-c. 175 CE), argued that the created order was evil and that the soul had to escape the body in order to achieve enlightenment, so Christ could not have become a human body without loss of divinity. Likewise, Docetists, who shared a Gnostic world view claimed, “If he suffered he was not God; if he was God he did not suffer.”
Christian apologists of the second century, such as Ignatius, Irenaeus, and Tertullian, appeal to the Virgin Birth to defend the incarnation against Gnostic and Docetic opponents, appealing primarily to Mary’s human motherhood as evidence of Christ’s humanity. In the words of Ignatius; “Be deaf, then, to any talk that ignores Jesus Christ, of David’s lineage, of Mary; who was really born, ate, and drank; was really persecuted under Pontius Pilate; was really crucified and died.” Tertullian goes to great lengths to emphasize the fleshiness of the birth of Christ, precisely to combat the heresy of Marcion:
Come now, beginning from the nativity itself, declaim against the uncleanness of the generative elements within the womb, the filthy concretion of fluid and blood, of the growth of the flesh for nine months long out of that very mire. Describe the womb as it enlarges from day to day, -heavy, troublesome, restless even in sleep, changeful in its feelings of dislike and desire. Inveigh now likewise against the shame itself of a woman in travail, which, however, ought rather to be honoured in consideration of that peril, or to be held sacred in respect of [the mystery of] nature. Of course you are horrified also at the infant, which is shed into life with the embarrassments which accompany it from the womb. … This reverend course of nature, you, O Marcion, [are pleased to] spit upon; and yet, in what way were you born? You detest a human being at his birth; then after what fashion do you love anybody? … Well, then, loving man [Christ] loved his nativity also, and his flesh as well…. Our birth He reforms from death by a second birth from heaven.
For Tertullian, as Christina Beattie puts it, “The human flesh which unites Christ with Mary is as intrinsic to his identity as the divinity which unites him with God, for without her there can be no true salvation of the flesh.”
In the fifth century the problem is reversed, as Nestorians referred to Mary as Christokos, to emphasize Mary was only the mother of the humanity of Christ and not his divinity. To correct this division between the humanity and deity of Christ, the Council of Ephesus (CE 431), affirmed by Chalcedon (CE 451), dubbed Mary, Theotokos (God-bearer), to affirm the divine and human unity of Christ. The definition of Chalcedon describes Christ as “truly God and truly man … as regards his Godhead, begotten of the Father before the ages, but yet as regards his manhood begotten, for us men and for our salvation, of Mary the Virgin, the God-bearer (Theotokos).”
As I have described it here, it may be that the focus on and eventual veneration of Mary, did not translate into a full embrace of the feminine, motherhood, or the earthly. As Luce Irigaray has described it, the veneration of Mary made of her “a likeness” or a simulacrum of the reality so that the feminine was put into the service of making “reproduction-production of doubles, copies, fakes, while any hint of their material elements, of the womb, is turned into scenery to make the show more realistic.”
Though the denigration of womanhood and the earthly can be traced to such early key figures as Augustine, it is precisely in Augustine that the Virgin Birth commanded a startling sort of orthodoxy. In one of Augustine’s Christmas Day Sermons based on Psalm 85:11 he describes the Virgin Birth as a joyous merger of heaven and earth:
Truth, which is in the bosom of the Father (Jn 1: 18), has sprung from the earth, in order also to be in the bosom of his mother. Truth, by which the world is held together, has sprung from the earth, in order to be carried in a woman’s arms. Truth, on which the bliss of the angels is incorruptibly nourished, has sprung from the earth, in order to be suckled at breasts of flesh. Truth, which heaven is not big enough to hold, has sprung from the earth, in order to be placed in a manger.
Augustine imagines Christ saying:
To show you that it’s not any creature of God that is bad, but that it’s crooked pleasures that distort them, in the beginning when I made man, I made them male and female. I don’t reject and condemn any creature that I have made. Here I am, born a man, born of a woman. So I don’t reject any creature I have made, but I reject and condemn sins, which I didn’t make. Let each sex take note of its proper honor, and each confess its iniquity, and each hope for salvation.
Beattie concludes that, despite his patriarchal tendencies and the tendency to denigrate the body, “Augustine thus affirms the goodness of the body, including the female body.”
So Mary’s motherhood of Christ repudiates both those who would denigrate the body or those who would question the deity of the human Jesus. It demands a recognition of the goodness of creation, even the messy side of creation in childbirth. Any fear of contamination is not due to the flesh but due to sin. As Augustine says in another work attributed to him, Christ defends Mary’s motherhood against a Manichaean by saying “She whom you despise, 0 Manichaean, is My Mother; but she was formed by My hand. If I could have been defiled in making her, I could have been defiled in being born of her.”
In Plato’s cave we encounter the symptomatic problem in human religion, philosophy, and thought, in that it would fly toward the sun to gain access to God but in Christ this world is turned upside down as the son has come to earth. In the human economy there is a forgetting of life and a death-dealing grab for truth beyond the stars, but the guiding star of Christmas night points us to a humble manger, most likely located in a cave outside of Bethlehem, where God is With Us.
 Justin Martyr, “First Apology” n. 33 in The First and Second Apologies, trans. with notes Leslie William Barnard in ACW 56 (1997), 46. I am following Christina Jane Beattie, God’s mother, Eve’s advocate: a gynocentric refiguration of Marian symbolism in engagement with Luce Irigaray (PhD University of Bristol, 1998). Quotes are from her dissertation at https://creativecommons.org/licenses/by-nc-nd/4.0/legalcode
 Ambrose, Expos. Ev sec. Luc., Lib. ii. 2,3 in Livius, The Blessed Virgin, 131.
 Henry Bettenson, Documents of the Christian Church (Oxford: Oxford University Press, 1979 ), 35.
 Tertullian, “On the Flesh of Christ” in The Writings of Tertullian, Vol. 2, trans. Peter Holmes, in ANCL 15 (1870), 170-71.
 Beattie, 102.
 In Bettenson, Documents, 51.
 Luce Irigaray, Speculum of the Other Woman (SP), trans. Gillian C. Gill. Ithaca, NY: Cornell University Press, 1985 (1974) 340.
 Augustine, “Sermon 185” n. I in Sermons 111/6 (184-229Z) on the Liturgical Seasons, trans. and notes Edmund Hill OP, ed. John E. Rotelle OSA, WSA III, 5 (1993), 21.
 Quoted from Beattie, 102.
 Tract. contr. quinque haeres., cap. v., Int. Opp. Augustini. Append., Tom. 8 in Livius, The Blessed Virgin, 70 (translation modified).