If you would like to read a very good explanation of Mary’s Magnificat, I heartily recommend Martyn Lloyd-Jones’ My Soul Magnifies the Lord. It is a collection of four meditations on the meaning of Christmas (published by Crossway Books) and is a mere 108 pages. Here are a couple of excerpts.
“Mary is rejoicing not so much in the fact that she is to be given this great privilege. Yes, she has been reminded by Elisabeth of what that is and of how people are going to call her blessed, and she repeats that: ‘from henceforth all generations shall call me blessed.’ But that is not the thing that really moves her. It is what God is doing — this historic event, this climactic action of God Himself. She is humbled and grateful at the thought of the fact that she is to be given a part and a place in this, but it is the thing itself that moves her and makes her sing and worship. She is filled with a sense of amazement, worship, adoration, and utter astonishment. She sees the inner meaning of the action. She has a glimmering of understanding of the whole purpose of salvation, what God is doing in bringing forth His Son into the world, even out of her womb” (p. 16).
Here he is describing how God has “put down the mighty from their seats.”
“But He has done it in a supreme manner. When the King of kings and the Lord of lords came into this world, He came into a stable. If you do not feel a sense of holy laughter within you, I do not see that you have a right to think you are a Christian. Thank God, this is the Gospel, this is salvation. God turning upside-down, reversing everything we have ever thought, everything we have taken pride in. The mighty? Why, He will pull them down from their seats. He has been doing so, and He is still doing so. If any man arises and says he is going to govern, to be the god of the whole world, you need not be afraid — he will be put down” (p. 45).
There’s much more, so get yourself a copy. It is a good book to give to someone who wants to know more about the Gospel, and it’s a rich book for the believer.