Double Run Passage for Alto and Soprano from "For Unto Us A Child Is Born" from Handel's "Messiah"

I believe that this passage is the most difficult passages in that chorus from the Messiah....it is like a pianist trying to do double-thirds in 16th-notes, which can also be difficult. The main problem is for the altos and the sopranos to listen to each other to make sure that the intonation and the pitches are right on even though the notes are played fast.

The Schrimer Edition of the "Messiah" also creates a challenge for the accompanist---that orchestral reduction for the piano does use this passage in either double sixths or double thirds as well.