This is the best thing on the internet today:
The Genius of Sacred Music as Heard in Seven Musical “Onomatopoeias”
by Msgr. Charles Pope
There are times when music, including sacred music, has an onomatopoetic quality; they sound like what their words are describing. For example, there are songs that describe the crucifixion featuring hammer blows in the background, and songs about the resurrection and ascension that feature notes soaring up the scale.