The Blessed Virgin Mary is the Second Eve

1. St. Justin:
     "We know that He, before all creatures, proceeded from the Father by His power and will, ... and by means of the Virgin became man, that by what way the disobedience arising from the serpent had its beginning, by that way also it might have an undoing. For Eve, being a virgin and undefiled, conceiving the word that was from the serpent, brought forth disobedience and death; but the Virgin Mary, taking faith and joy, when the Angel told her the good tidings, that the Spirit of the Lord should come upon her and the power of the Highest overshadow her, and therefore the Holy One that was born of her was Son of God, answered, 'Be it to me according to Thy word.'" - Tryph. 100.

2. Tertullian:
     "God recovered His image and likeness, which the devil had seized, by a rival operation. For into Eve, as yet a virgin, had crept the word which was the framer of death. Equally into a virgin was to be introduced the Word of God which was the builder-up of life; that, what by that sex had gone into perdition, by the same sex might be brought back to salvation. Eve had believed the serpent; Mary believed Gabriel; the fault which the one committed by believing, the other by believing has blotted out." - De Carn. Christ. 17.

3. St. Irenaeus:
     "With a fitness, Mary the Virgin is found obedient, saying, 'Behold thy handmaid, O Lord; be it to me according to Thy word.' But Eve was disobedient; for she obeyed not, while she was yet a virgin. As she, having indeed Adam for a husband, but as yet being a virgin ... becoming disobedient, became the cause of death both to herself and to the whole human race, so also Mary, having the predestined man, and being yet a Virgin, being obedient, became both to herself and to the whole human race the cause of salvation. And on account of this the Lord said, that the first should be last and the last first. And the Prophet signifies the same, saying, 'Instead of fathers you have children.' For, whereas the Lord, when born, was the first-begotten of the dead, and received into His bosom the primitive fathers, He regenerated them into the life of God, He Himself becoming the beginning of the living, since Adam became the beginning of the dying. Therefore also Luke, commencing the line of generations from the Lord, referred it back to Adam, signifying that He regenerated the old fathers, not they Him, into the Gospel of life. And so the knot of Eve's disobedience received its unloosing through the obedience of Mary; for what Eve, a virgin bound by incredulity, that Mary, a virgin, unloosed by faith." - Adv. Her. iii. 22. 34.

      "As Eve by the speech of an Angel was seduced, so as to flee God, transgressing His word, so also Mary received the good tidings by means of the Angel's speech, as as to bear God within her, being obedient to His word. And, though the one had disobeyed God yet the other was drawn to obey God; that of the virgin Eve the Virgin Mary might become the advocate. And, as by a virgin the human race had been bound to death, by a virgin it is saved, the balance being preserved, a virgin's disobedience by a virgin's obedience." - Ibid. v. 19.