Bach's Extraordinary Temperament: Our Rosetta Stone--1

Johann Sebastian Bach's 1722 title-page for Das wohltemperirte Clavier contains a hand-drawn schematic of his expected keyboard temperament, now deciphered in 2004 by Bradley Lehman. The article presents historical and theoretical analysis of this temperament, and its implications for further study. Bach notated this specific unequal tuning as part of his audition material for the Leipzig position: to demonstrate his readiness to teach all aspects of keyboard practice, and probably also the way he intended to tune the organs upon securing the job (as is corroborated by his later Leipzig organ compositions). Approximately half the pieces in the WTC directly demonstrate salient and unique features of this temperament, showing how deeply Bach understood this intonational resource, and how he allowed his musical themes and working methods to be catalysed by its presence. With Bach's musically colourful and all-purpose solution installed on a keyboard, all tonal music is lively and clear, without any of the typical harmonic problems encountered in other contemporary unequal temperaments. The intonation affects other areas of performance practice as well, especially in Affekt and phrasing, as it suggests the specific melodic/harmonic tensions Bach expected and deployed in his art. An inspection of Bach's earliest music reveals that he already knew this temperament (or something similarly efficacious) at the beginning of his career; this was simply his everyday practical way to tune keyboards, probably learned from his family. And he and his sons never necessarily abandoned this in favour of equal temperament, during its rise in their culture.