24 The Lord is with her whom He has filled with His grace and made blessed. She is designated by the heavenly messenger sent to her as the Virgin from whom, by the power of the Holy Ghost, the expected Saviour of nations is to come forth clothed in our humanity. The more she wonders at the sublime dignity and gives thanks to the power and mercy of God, the more does she, conscious of no merit in herself, grow in humility, promptly proclaiming and consecrating herself the handmaid of God even while she becomes His Mother.
Source: Magnae Dei Matris (Vatican.va)