“You are all fair, my love; there is no flaw in you.” (Song of Songs 4:7).

Mary was always immune from every sin. First of all in her very conception. For it is reasonably believed that Mary received greater gifts of grace than all others, since she gave birth to “the Only Begotten of the Father, full of grace and of truth.” Hence it is written, “The Angel said to her, ‘Hail, full of grace, the Lord is with thee, Blessed art thou among women’.” (Luke 1:28).

Moreover, it is to be observed that it was granted by way of privilege to others, to be sanctified in the womb; for example, to Jeremias, of whom it is written (Jer. 1:5): ““Before I formed you in the womb I knew you, and before you were born I consecrated you;” and again to John the Baptist, of whom it is written (Luke 1:15), and he will be filled with the Holy Spirit, even from his mother’s womb.”

(Therefore, in order that Mary might receive more grace than these, she had to be not only sanctified in the womb but also preserved from the original stain of sin.)

            But this infusion of grace took place not before animation, but at the very first instant of animation. For the thins of the Old Testament were figures of the New according to 1 Cor. 12: “All things happened to them in figure.” Now the sanctification of the tabernacle, of which it is written, Ps. 45:5 (44:5), “Through thee we push down our foes; through thy name we tread down our assailants,” seems to signify the sanctification of the Mother of God who is called God’s Tabernacle according to Ps. 18:6, “He hath set his tabernacle in the Sun.” But of the tabernacle it is written (Ex. 39:31): “So all the work of the tabernacle and of the roof of the testimony was finished.” Therefore, also, the Blessed Virgin was not sanctified until after all in her were perfected, namely, her body and soul, that is, in the same instant.

Secondly, Mary’s whole life was free from sin. For God so prepares and endows those whom He selects for some particular office, that they are rendered capable of fulfilling it, according to 2 Cor. 3:6: “who has qualified us to be ministers of a new covenant.” Now the Blessed Virgin was chosen by God to be His Mother. Therefore, there can be no doubt that God, by His grace, made her worthy of that office, according to the words spoken to her by the Angel (Luke 1:30-31), “Do not be afraid, Mary, for you have found favor with God. And behold, you will conceive in your womb and bear a son, and you shall call his name Jesus.” But she would not have worthy to be the Mother of God if she had ever sinned. First, because the honor of the parents reflects upon the child, according to Prov. 17:6 – “the glory of sons is their fathers”; and consequently, on the other hand, the Mother’s shame would have reflected on her Son. Secondly, because of the singular affinity between her and Christ Who took flesh from her. And it is written (2 Cor. 6:15): “What accord has Christ with Be′lial?” Thirdly, because of the singular manner in which the Son of God, “Who is the Divine Wisdom” (1 Cor. 1:24), dwelt in her, not only in her soul but in her womb. And thus, it is written (Wis. 1:4): “because wisdom will not enter a deceitful soul, nor dwell in a body enslaved to sin.”

We must therefore confess sharply that the Blessed Virgin Mary committed no actual sin, either moral or venial; so that what is written (Song. 4:7), is fulfilled: “You are all fair, my love; there is no flaw in you.” (3a. q.27)