Quinque sur l'octave

The chaconne was particularly dear to French baroque composers, from Lully to Leclair, from Marais to Rameau, and Boismortier was no exception. In one of his most original works, the Quinque sur l’octave, ou espece de dictionaire harmonique (Quintet based on the octave, or a type of harmonic dictionary), Boismortier employs a chaconne to illustrate and elaborate upon the so-called règle de l’octave (rule of the octave), a formula commonly used in the eighteenth century for the harmonisation of ascending and descending diatonic scales. Using the C major scale as his ground bass, he proposes increasingly varied diminutions over alternative harmonisations, and in so doing ‘redefines’ the original règle.