A good friend reminded me that Question 22 of the Westminster Shorter Catechism is a great one to meditate on during the advent season.
Q. 22. How did Christ, being the Son of God, become man?
A. Christ, the Son of God, became man, by taking to himself a true body and a reasonable soul, being conceived by the power of the Holy Ghost in the womb of the virgin Mary, and born of her, yet without sin.
Here is an mp3 of the song.