The circle of fifths progression (I–IV–vii–iii–vi–ii–V–I) was a stalwart of the Baroque era in music. You will find many examples of this progression in the music of Bach, Handel, and Vivaldi, especially in minor (i–iv–VII–III–VI–ii–V–i) with the subtonic VII (see Definition 7.3.2.
This circle (the circle of fifths for harmonic progression) is different than the circle of fifths for key signatures because this circle of fifths for harmonic progression contains diatonic notes only. The circle of fifths for key signatures (Figure 2.3.4) contained all 12 notes of the chromatic scale.
The circle of fifths progression has a feeling of inevitability about it because it consists of harmonic sequences. To understand harmonic sequence we will first look at melodic sequences, since the bass line is the “melody” in a harmonic sequence. Ask yourself what happens after this melodic idea:
Sequences can be short or long. For example, look at this familiar idea and notice how all four bars are sequenced down a step in the following four bars.
Sometimes we will hear a circle of fifths sequence where some of the chords are not in root position, as in the Handel and Mozart examples. In these two examples, we are hearing the sequence of the roots, even though they are not clearly presented in the bass.