"It Came upon the Midnight Clear"

Since July, I've been slowly working my way through the book I used in my beginner's piano class in college (James Bastien's The Older Beginner Piano Course).  At the end of October, I re-learned how to turn the thumb under or cross the hand over in order to play a scale with one hand.  To demonstrate this, the book provides a few phrases from some Christmas songs that are built on scales.  One of these is the third line in "It Came upon the Midnight Clear":

After practicing this for a few days, I started thinking about that octave drop that accompanies "Peace on the earth."  I realized that it retains a distinction from the Luke 2 text that the lyrics are based on: "And suddenly there was with the angel a multitude of the heavenly host praising God and saying, 'Glory to God in the highest, and on earth peace among those with whom he is pleased!'" (Luke 2:13-14).  There's the highness of God and the lowness of those on the earth.  While the lyrics here don't include "Glory to God in the highest," they still have that same idea of the difference of levels by setting the "peace" and "the earth" on the same note an octave apart.

For what it's worth, both Handel (in the Messiah: No. 17 - Glory to God in the Highest) and Saint-Saëns (in his Christmas Oratorio: II. Recit et chœur) do similar things with the same text.  They set the "highest" with higher voices and the "on earth" with lower ones.  I hadn't noticed until writing this, but Handel has an octave drop for "peace on earth" too, between A notes in the bass voice:

(notation found here)