Invention No. 5 BWV 776 in E Flat Major by Bach

This invention is based on two subjects presented in measures 1 to 4.

Subject 1 (S1) is played by the soprano, while the bass plays subject 2 (S2).
The first four measures modulate to the dominant key (Bb major).
Both subjects reappear in measures 5 to 8, but this time the soprano plays S2 while the bass plays S1.
Small changes (marked in red), allows us to return to Eb major in measure 9.