Mary was physically untouched, but she was also free from every blemish of sin at the Assumption and thus aptharti (incorrupt or immaculate). She was free from actual sin from that point. For Ambrose, sin indicates the inherited imperfection of Adam and Eve's revolt in the Garden of Eden. Mary was a virgin who was not only incorrupt (incorrupta), but also a virgin made inviolate by the grace of God the Father and was also free from every blemish of sin (per gratiam ab omnia incorrupta labe peccati). Ambrose uses the words omnia incorrupta to show that she was without any sin and was thus pure in a literal sense. The use of the Greek aphtharton shows a correspondence with the Latin incorrupta. In the Vulgate Bible, 1 Corinthians 9:25, aphtharton is translated as incorrupta. In the Song of Songs 4:12 it states: "A garden enclosed is my sister, my spouse; a spring shut up, a fountain sealed." Early Orthodox Christians understood these two passages as portentous to the notion that the womb of the Virgin Mary is "shut" and "sealed" by God, and was not to be "opened" by her natural childbirth of Jesus the Logos. They maintained that the Lord passed through her closed womb by making use of divine power which is analogous to that power which He used to appear to His disciples in the upper room where the doors were shut (John 20:19). Mary was immensely humble and her humility is demonstrated in her free will and willing response to partake in the Incarnation which was the initiative of God the Father. Ambrose writes: "And then, how she also went every year to Jerusalem at the solemn day of the Passover, and went with Joseph. Everywhere is modesty the companion of her singular virtues in the Virgin. This, without which virginity cannot exist, must be the inseparable companion of virginity. And so Mary did not go even to the temple without the guardianship of her modesty" (Ambrose of Milan, Concerning virginity: Book II).

Ambrose also stresses her selection for her role as the Theotokos as thus being fully understandable:

Such has the Evangelist shown her, such did the angel find her, such did the Holy Spirit choose her. Why delay about details? How her parents loved her, strangers praised her, how worthy she was that the Son of God should be born of her. She, when the angel entered, was found at home in privacy, without a companion, that no one might interrupt her attention or disturb her; and she did not desire any women as companions, who had the companionship of good thoughts. Moreover, she seemed to herself to be less alone when she was alone. For how should she be alone, who had with her so many books, so many archangels, so many prophets? (Ambrose of Milan, Concerning virginity: Book II).

Mary is thus gifted with grace resulting from God's pleasure in her person as a unique and perfect individual since her entrance into the world. Mary happily accepts her role: "Behold the maidservant of the Lord! Let it be to me according to thy word" (Luke 1:38). To Ambrose this was an indication that the upper classes in particular could not withdraw from a productive life in which for example, a family needed to be served or from their political responsibilities for that matter, and Mary's example as a committed individual was the ideal situation to emulate. It is evident from the historical record that the Mariology of Ambrose influenced the policies of a number of contemporary Popes, including Pope Damasus, Pope Siricius and Pope Leo the Great. He suggests in all his writings on the Virgin Mary that she was the perfect role-model of how to live, especially for those seeking to bury their heads in the soil like the proverbial ostrich, and shun their duties and many responsibilities to society. The Virgin Mary brought Christ forth as a virgin and she is blessed as the "gate" through which the Holy Spirit entered:

5. Mary heard the voice of the Angel, and she who before had said How shall this be? not asking from want of faith in the mode of generation, afterwards replied, Behold the handmaid of the Lord, be it unto me according to thy word. This is the virgin who conceived, this the virgin who brought forth a Son. For thus it is written, Behold a virgin shall conceive and bear a Son; declaring not only that she should conceive as a virgin, but also that she bring forth as a virgin.

6. But what is that gate of the sanctuary, that outward gate which looketh towards the East, which remains shut, and no man, it is said, shall enter in by it but the Lord, the God of Israel. Is not Mary this gate, by whom the Saviour entered into the world? This is the gate of righteousness, as He Himself said, Suffer us to fulfil all righteousness. Blessed Mary is the gate, whereof it is written that the Lord hath entered in by it, therefore it shall be shut after birth; for as a virgin she both conceived and brought forth (Ambrose of Milan, Letter XLII, Letter of the Council of Milan to Pope Siricius, S5 and S6, BCE 389).

It was becoming somewhat trendy in the Roman Empire for women of means and great influence to seek a Spartan-like existence in which virtue and self-sufficiency were desirable traits. Ambrose linked virginity very closely with the idea of Christian salvation and to an extent made it an indispensable part of being a Christian to serve his ends. In any event, the ritual of the consecration of virgins in the early Church was based on the marriage ceremony between a man and a woman and was thus equally if not more important. He used the debate on virginity and its merits to suit distinct needs he had at different times, but also explained that women had a maternal role of imparting Christian virtues in their offspring. In 395 BCE, Ambrose delivered the funeral oration for the Emperor Theodosius. In this oration he suggested that Helena, the Empress who was mother of Constantine, had nurtured him for his role as the one who would give Christianity its rightful place in the world. In this sense, Helena and Mary were similar mothers: "Mary was visited, so that Eve be liberated; Helena was visited so that emperors be redeemed" (Ambrose of Milan 1985: 244-245). There is also a distinct variance in his stance on virginity in particular in his two works De Virginibus and De Virginitate. In the latter he tended to discard the overly ascetic interpretation of scripture and the virginity of the Virgin Mary who was martyr-like in description. She instead becomes the Bride of Christ (Neumann 1962: 33-47). The angel explained to Mary how she would bear Jesus Christ: "The Holy Spirit will come upon you, and the power of the Highest will overshadow you; therefore, also, that Holy One Who is to be born will be called the Son of God" (Luke 1:35). Mary does not hesitate, but actively seeks to choose to serve and obey God and to do His will. A virgin birth is indeed worthy of God in human form: "Which human birth would have been more worthy of God, than the one, in which the Immaculate Son of God maintained the purity of his immaculate origin while becoming human?" (Ambrose of Milan CSEL 64, 139).

Many women who were contemporaries of Ambrose did not accept or recognise the expectations placed upon them and Ambrose consequently advised Christian virgins to be supportive of their families and take their duties and responsibilities seriously or the result would be a life-long battle (Ambrose of Milan 2007: 111-113). He urges them: "If you conquer your family, you conquer the world" (Ambrose of Milan, De Virginibus, II, c. 15). Virgins will be rewarded for their virtue when they die and Mary will rejoice with them:

What a procession shall that be, what joy of applauding angels when she is found worthy of dwelling in heaven who lived on earth a heavenly life! Then too Mary, taking her timbrel, shall stir up the choirs of virgins, singing to the Lord because they have passed through the sea of this world without suffering from the waves of this world. Exodus 15:20 Then each shall rejoice, saying: I will go to the altar of God; to God Who makes my youth glad; and, I will offer unto God thanksgiving, and pay my vows unto the Most High (Ambrose of Milan, Concerning virginity:-Book II).

Mary was the most blessed of women, and the perfect model of obedience to the will of God. Ambrose considered virginity to be far superior to marriage and perceived Mary to be the ultimate role model of virginity (Ambrose of Milan, De Virginibus 2, 6). By pointing to Mary as the Mother of God, and the church which is the Mystical Body of Christ, Ambrose sought to locate in Mary the solution for a divided Christian Roman Empire. To Ambrose, Mary is the perfect example since: "...Mary, a virgin not only undefiled but a virgin whom grace has made inviolate, free of every stain." Ambrose states: "The virgin birth was worthy of God. Which human birth would have been more worthy of God, than the one, in which the Immaculate Son of God maintained the purity of his immaculate origin while becoming human?" (Ambrose of Milan CSEL 64, 139). Mary as a virgin who conceived, is to be honoured and venerated and we honour her as our mother. She was totally respectful to the call of God and immediately resolved to be obedient to whatever she was to do:

And so, too, when Gabriel visited her, Luke 1:28 did he find her, and Mary trembled, being disturbed, as though at the form of a man, but on hearing his name recognized him as one not unknown to her. And so she was a stranger as to men, but not as to the angel; that we might know that her ears were modest and her eyes bashful. Then when saluted she kept silence, and when addressed she answered, and she whose feelings were first troubled afterwards promised obedience (Ambrose of Milan, Concerning virginity: Book II).

Ambrose says that we should: "...confess, that Christ the Lord was born from a virgin, and therefore we reject the natural order of things. Because not from a man she conceived but from the Holy Spirit" (Ambrose of Milan, De Mysteriis, 59, PG 16, 410).