A harmonic sequence repeats a short chord pattern at a new pitch level. The repeated shape gives a progression momentum and makes a longer phrase feel like one connected idea.
A sequence can preserve exact intervals, or it can stay inside a key and adjust chord qualities to fit the scale. The second approach is often called a diatonic sequence.
Repeat a small cell
In C major, the ii–V cell Dm–G can move up one scale step to iii–vi, Em–Am. The roots rise while the basic two-chord idea repeats.
Join the cells into Dm – G – Em – Am and listen for the repeated motion.
Try it
- Write a two-chord cell with a clear root-motion pattern.
- Repeat it at a different scale degree, changing chord quality only when the key requires it.
- Decide whether the sequence should continue, turn toward a cadence, or break for contrast.
Key takeaway
A sequence creates forward motion through repetition. Its pattern is recognizable, but its destination is still yours to choose.