Wie schön leuchtet der Morgenstern
, BWV764, sets the first three lines of the choral plus the beginning of the repeat of the first. The chorale melody appears as a cantus firmus in the right hand above imitative accompanying voices. To introduce the repeat of the first line of the tune, just before the music breaks off, Bach expands his motif with extra decorative notes and also alters the speed at which the harmony changes.
from notes by Stephen Westrop © 1999