Mary, Mother of the Son

and, as Pope John Paul II explains, collaborator in the work of salvation.  Excerpts:

...After becoming aware of the maternal role of Mary, who was venerated in the teaching and worship of the first centuries as the virginal Mother of Jesus Christ and therefore as the Mother of God, in the Middle Ages the Church's piety and theological reflection brought to light her cooperation in the Savior's work.

This delay is explained by the fact that the efforts of the Church Fathers and of the early Ecumenical Councils, focused as they were on Christ's identity, necessarily left other aspects of dogma aside. Only gradually could the revealed truth be unfolded in all its richness. Down the centuries, Mariology would always take its direction from Christology. The divine motherhood of Mary was itself proclaimed at the Council of Ephesus primarily to affirm the oneness of Christ's person. Similarly, there was a deeper understanding of Mary's presence in salvation history.

2. At the end of the second century, St. Irenaeus, a disciple of Polycarp, already pointed out Mary's contribution to the work of salvation. He understood the value of Mary's consent at the time of the Annunciation, recognizing in the Virgin of Nazareth's obedience to and faith in the angel's message the perfect antithesis of Eve's disobedience and disbelief, with a beneficial effect on humanity's destiny. In fact, just as Eve caused death, so Mary, with her "yes", became "a cause of salvation" for herself and for all mankind (cf. Adv. Haer., III, 22, 4; SC 211, 411). But this affirmation was not developed in a consistent and systematic way by the other Fathers of the Church.

Instead, this doctrine was systematically worked out for the first time at the end of the 10th century in the Life of Mary by a Byzantine monk, John the Geometer. Here Mary is united to Christ in the whole work of Redemption, sharing, according to God's plan, in the Cross and suffering for our salvation. She remained united to the Son "in every deed, attitude and wish" (cf. Life of Mary, Bol. 196, f. 122 v.). Mary's association with Jesus' saving work came about through her Mother's love, a love inspired by grace, which conferred a higher power on it: love freed of passion proves to be the most compassionate (cf. Ibid., Bol. 196, f. 123 v.)...