Many songs have a simple one-part form which repeats. In this situation different sections can be created by thoughtful use of harmonies and variation in the instrumentation. The spiritual Nobody’s Fault but Mine is a good example. Here are the first two verses.
Because of the nature of the lyrics, a subtle arrangement with a single voice suits this song. However, after several verses, this may become rather dull. Other voices could be added, or the backing could be changed to add variety. On the recording, both these things have been done. A completely new instrumental section has also been added. This means that when the singer returns to the first verse, it feels fresh.
To build the dynamics, a choir has been added to the final section. The choir sings the melody in unison, while the lead singer improvises responses based on the lyrics. In the final verse, the choir breaks away from the melody and sings harmonies as a section. These harmonies are notated here. Notice the use of 7th and 9th chords.