And Mary said,
"My soul magnifies the Lord,
and my spirit rejoices in God my Saviour,
for he has looked with favor on the lowliness of his servant.
Surely, from now on all generations will call me blessed;
for the Mighty One has done great things for me,
and holy is his name.
His mercy is for those who fear him
from generation to generation.
He has shown strength with his arm;
he has scattered the proud in the thoughts of their hearts.
He has brought down the powerful from their thrones,
and lifted up the lowly;
he has filled the hungry with good things,
and sent the rich away empty.
He has helped his servant Israel,
in remembrance of his mercy,
according to the promise he made to our ancestors,
to Abraham and to his descendants forever."
Because of its juxtaposition to the birth of the Christ, I have trouble relating both events metaphorically.
The verses you ask about constitute the beautiful poem known as "The Magnificat," from its Latin phrasing. It is closely based on Hannah's prayer at 1 Samuel 2:1-10. In both cases a woman—one elderly and barren, one young and virginal—find themselves pregnant through divine intervention. Mary's is certainly the most challenging and surprising situation. Hannah is married; she has long been praying for a son, and is eager to receive him. Mary is betrothed but not yet married, and a pregnancy will cause a great burden of shame and judgment in the world around her. Yet, like Hannah, she sees the Good and gratefully accepts the role she is called upon to play. For us, too, the energy of the Divine may express in surprising ways, calling us into situations we had not expected. But, like Mary, we can be absolutely sure—centered in perfect faith—that the spiritual result of accepting the role will be rich, joyful, and filled with infinite love.
The result of Mary's spiritual surrender led, of course, to the birth we celebrate at Christmas. Because she was open to the Truth that she was being called to a higher spiritual purpose that would sometimes challenge and conflict with the human experience she was living, the collective consciousness of all humanity would be profoundly deepened. We all are "called" to give birth to new spiritual possibilities—it's why we're here, infinite spiritual beings in limited human form. And we can never know how important and far-reaching our choices may prove to be.