On interpreting Bach


We have attempted to discover formal rules for transcribing into musical notation the fugue subjects of the Well-Tempered Clavier, as this might be done by an amanuensis listening to a'deadpan' performance on the keyboard. What we have in fact done is to write two'parsing' programs, one for determining the metre and the other for explicating the harmonic relations between the notes of a Bach fugue subject. In writing these programs, which take account only of the note lengths and positions on the keyboard, we have attempted to make explicit our intuitive understanding of musical rhythm and harmony in general, and also to take account of one or two stylistic features which seem to distinguish Bach from some other classical masters. If our rules are to be able to decide the time signature and the key signature from the durations of the notes and their positions on the keyboard, some assumption must be made about how much of these data may safely be assumed congruent, and may therefore be used as evidence in reaching the required decision.