11 In the salvific design of the Most Holy Trinity, the mystery of the Incarnation constitutes the superabundant fulfillment of the promise made by God to man after original sin, after that first sin whose effects oppress the whole earthly history of man (cf. Gen. 3:15). And so, there comes into the world a Son, "the seed of the woman" who will crush the evil of sin in its very origins: "he will crush the head of the serpent." As we see from the words of the Protogospel, the victory of the woman's Son will not take place without a hard struggle, a struggle that is to extend through the whole of human history. The "enmity," foretold at the beginning, is confirmed in the Apocalypse (the book of the final events of the Church and the world), in which there recurs the sign of the "woman," this time "clothed with the sun" (Rev. 12:1). Mary, Mother of the Incarnate Word, is placed at the very center of that enmity, that struggle which accompanies the history of humanity on earth and the history of salvation itself. In this central place, she who belongs to the "weak and poor of the Lord" bears in herself, like no other member of the human race, that "glory of grace" which the Father "has bestowed on us in his beloved Son," and this grace determines the extraordinary greatness and beauty of her whole being. Mary thus remains before God, and also before the whole of humanity, as the unchangeable and inviolable sign of God's election, spoken of in Paul's letter: "in Christ...he chose us...before the foundation of the world,...he destined us...to be his sons" (Eph. 1:4, 5). This election is more powerful than any experience of evil and sin, than all that "enmity" which marks the history of man. In this history Mary remains a sign of sure hope.
Source: Redemptoris Mater (Vatican.va)