A circular progression cycles the same harmonic pattern over and over again: The harmonies revolve like a spinning merry-go-round.
Circular progressions are common in commercial music. The theme song from the television series “The Office” is based on one.
Circular progressions are also ubiquitous in improvisatory and participatory music: They allow for independence and spontaneity within a shared, reliable framework. Jazz’s “12-bar blues” and “Boogie-Woogie” bass-line are iconic examples.
In classical music, chaconnes, passacaglias and theme and variations incorporate circular progressions. Each time the progression is played, it is expressed in a new way. This excerpt from Georg Friedrick Handel’s Passacaglia in g-minor cycles the harmonic progression four times.
In this excerpt from Sergei Prokofiev’s Violin Concerto No. 2, the solo violin traces its languorously evolving melody over a circular progression, which cycles eight times. Only in the last cycle is there is a small change in the harmonic progression.
On the other hand, a linear progression keeps changing, incorporating new chords and patterns. This excerpt from Wolfgang Amadeus Mozart’s Piano Concerto No. 24 in c-minor is a linear progression.
Circular progressions are frequently used for sustaining a mood or elaborating on a state of mind. Linear progressions serve a stronger narrative purpose: They allow the music to progress to new destinations and incorporate greater contrast. Most commercial songs consist of circular progressions: The words may tell a story but the harmony generally revolves in a circle. In contrast, classical music generally incorporates both types: As a result, the music itself can tell an expansive, evolving tale.