Rules
- Four quarter notes against each note of the cantus firmus.
- The first beat is consonant; the others may contain dissonances as passing tones or neighbor tones.
- Typical figures allowed: the nota cambiata (descends by step to a dissonance, leaps down a third, rises by step) and the double neighbor.
- Avoid parallel fifths and octaves between consecutive first beats and from a weak beat to the next first beat.
- The line must have direction: long scales, few leaps.
Example in C major
Cantus firmus: C4 | D4 …
Counterpoint above: C5 B4 A4 G4 | F4 …
C5 (octave) consonant; B4 (seventh) passing; A4 (sixth) consonant; G4 (fifth) consonant; then F4 over D4 is a third: arrival by step and consonance on the strong beat.
What it teaches
It is the foundation of lines in continuous motion over slow harmonies: jazz walking bass (chord tones on the strong beats, chromatic and passing notes on the others), arpeggios and string figurations, sixteenth-note synth lines.
Real example
In “Jesus bleibet meine Freude” (from Bach's Cantata BWV 147, 1723) the continuous line in triplets flows over the long notes of the chorale: many notes against one, with the consonances falling on the points of support. The same principle governs the jazz walking bass.