But why is Mary invited to rejoice in this way? The answer is to be found in the second part of the greeting: “The Lord is with you”. Here too, if we are to understand correctly the meaning of these words we must turn to the Old Testament. In the Book of Zephaniah, we find these words “Sing aloud, O daughter of Zion.... The King of Israel, the Lord, is in your midst.... The Lord, your God, in your midst, a warrior who gives victory” (3:14-17).In these words a twofold promise is made to Israel, to the daughter of Zion: God will come as a saviour and will pitch his tent in his people’s midst, in the womb of the daughter of Zion. This promise is fulfilled to the letter in the dialogue between the Angel and Mary. Mary is identified with the people espoused by God, she is truly the daughter of Zion in person; in her the expectation of the definitive coming of God is fulfilled, in her the Living God makes his dwelling place. (Pope Benedict XVI, General Audience, 19 December 2012)