From Joseph Cardinal Ratzinger:
The annunciation to Mary happens to a woman, in an insignificant town in half-pagan Galilee, known neither to Josephus nor the Talmud. The entire scene was "unusual for Jewish sensibilities. God reveals himself, where and to whom he wishes." Thus begins a new way, at whose center stands no longer the temple, but the simplicity of Jesus Christ. He is now the true temple, the tent of meeting.
The salutation to Mary (Lk 1:28-32) is modeled closely on Zephaniah 3: 14-17: Mary is the daughter Zion addressed there, summoned to " rejoice", in formed that the Lord is coming to her. Her fear is removed, since the Lord is in her midst to save her. Laurentin makes the very beautiful remark on this text: "... As so often, the word of God proves to be a mustard seed.... One understands why Mary was so frightened by this message (Lk 1:29). Her fear comes not from lack of understanding nor from that small-hearted anxiety to which some would like to reduce it. It comes from the trepidation of that encounter with God, that immeasurable joy which can make the most hardened natures quake."
In the address of the angel, the underlying motif the Lucan portrait of Mary surfaces: she is in person the true Zion, toward whom hopes have yearned throughout all the devastations of history. She is the true Israel in whom Old and New Covenant, Israel and Church, are indivisibly one. She is the "people of God" bearing fruit through God's gracious power. ...
Transcending all problems, Marian devotion is the rapture of joy over the true, indestructible Israel; it is a blissful entering into the joy of the Magnificat and thereby it is the praise of him to whom the daughter Zion owes her whole self and whom she bears, the true, incorruptible, indestructible Ark of the Covenant.