You too are blessed because you have heard and believed. The soul of every believer conceives and brings forth the Word of God and recognizes his works. Let Mary's soul be in each of you to glorify the Lord. Let her spirit be in each of you to rejoice in the Lord. Christ has only one mother in the flesh, but we all bring forth Christ by faith. Every soul free from the contamination of sin and inviolate in its purity can receive the Word of God.
St. Ambrose (339-397), Commentary of Luke's Gospel
Further reading
Ambrose connects Mary’s believing response with the life of every believer. Caryll Houselander’s The Reed of God develops a related meditation on receptivity to God and bearing Christ into ordinary life, offering a reflective companion to this short passage.