You can listen to the examples by clicking on the scores.

Excerpt from the original Version from J.S. Bach. The slightly unexpected harmonic event (submediant / deceptive cadence) is marked in red (scores are provided only for the critical measures, the sound file also plays the measures preceding and following these measures):
regular chord-sequence


This is a version in which the slightly unexpected harmonic event was rendered expected (red, now it's a tonic chord):
regular chord-sequence


This is a version in which the slightly unexpected harmonic event was rendered very unexpected (red, now it's a Neapolitan sixth chord)
regular chord-sequence