Adam and Eve were also graced with preternatural gifts at their creation, infused knowledge, immortality of the body and integrity.
Infused knowledge is the ability to recognize the providence of God. Immortality of the body means that the body is immune to disease, incorruptible of body. Integrity is the perfect obedience of emotions to the intellect, to the will. It is the absence of concupiscence, the inclination to sin, though not necessarily to external temptation, as is evident in Adam and Eve's fall to the temptation of the serpent.
These preternatural gifts were lost by our first parents when they committed original sin. No human through the long history of humanity have regain these gifts. Not even Christs death on the cross restored them the humanity. Except for one. Except for the one created without the stain of original sin. Except for Mary.
The knowledge of Mary's sinless nature was not something created by the medieval Church, it was a belief common among the faithful from the second century. It only logically follows that Mary would posses those gifts which were integral to our humanity prior to their loss due to sin.Infused knowledge is the ability to recognize the providence of God. Mary realized the supernatural significance of things others did not, so as Scripture says she “pondered them in her heart,” and eventually revealed them to St. Luke, where he recorded them in his Gospel.
Integrity is the perfect obedience of emotions to the intellect, to the will. Mary was not troubled by concupiscence, she had not inclination to sin, though she was tempted by external temptation as are all members of the human race, as were Adam and Eve. But though she was tempted she did not sin, not even venial sins.
Finally, immortality of the body means she was not subject to disease. In a very real way her Ascension into Heaven was a result of her preternatural gift of bodily incorruptibility.The supernatural gift lost by Adam and Eve was to be in Gods family, that is to be Full of Grace. This is a gift that God returned to us through Jesus Christ in the Sacrament of Baptism. It is the gift that Mary possessed without baptism, because of her Immaculate Conception.
None of these gifts were Mary's by virtue of any act that she committed. She did not earn them, no more than we can earn God's gift of salvation. They were Gift's of God to His Mother.
In a very real way Mary was part of God' plan from the beginning. She is prefigured in the Old Testament, her place in salvation history reflected in the Book of Kings and in Psalms, in the relationship of the King of Israel to the Queen Mother. She is the Queen in Ophir , the King's daughter, who will be the mother of the King, and whose sons will be the princes of the Earth, who the nations will praise forever.
Through God's gifts she, who was to remain a virgin, saved from the pain of labor, which was a punishment visited on Eve as a result of Original Sin, would have her heart pierced at the foot of the cross, she would never know the death of corruption of the body. She was the first to receive the gift of Her only Son's victory over death. the gift that we will receive at the Last Judgement.
In the Eastern Churches, including the Eastern Catholic Churches the Feast of the Assumption is celebrated as the Dormition of the Theotokos, that is the falling asleep of the Mother of God.