The Council said: "By her belief and obedience, not knowing man but overshadowed by the Holy Spirit, as the new Eve she brought forth on earth the very Son of the Father" (Dogmatic Constitution Lumen Gentium 63). It is a point on which the Fathers of the Church insisted: Mary conceived Jesus in the faith and then in the flesh, when she said "yes" to the announcement that God addressed her through the intermediary of the Angel.
What does that mean? That God did not want to become a man by ignoring our freedom; that he wanted to go through the free assent of Mary, through her "yes." He asked her, "Are you willing to do this?" And she said, "Yes."
But what happened to the Virgin Mother in a unique way is also realized spiritually in us when we welcome the Word of God with a heart that is good and sincere, and when we put it into practice. It is as if God took flesh in us and came to dwell in us, since he makes his dwelling in those who love him and observe his Word. It is not easy to understand this, but, yes, it is easy to feel it in our heart.
Prayer for the Marian Day on the occasion of the Year of Faith – October 12, 2013