Mary's Mind: The Spirit and the Annunciation

Why was Mary "troubled" or distressed by Archangel Gabriel's announcement? What important fact do we learn about her expectation for her future by her response: "I do not know man." What is the Holy Spirit's role in the Incarnation and why does salvation begin with this?

Music attribution: "Galway" Kevin MacLeod (incompetech.com) Licensed under Creative Commons: By Attribution 4.0 License http://creativecommons.org/licenses/b...