Score Reading: A Bach Autograph

There are many special features to be observed on the beautiful manuscript of Bach’s [Prelude and] Fugue in G minor, BWV 535 for organ, the opening page of which is shown above: 1] Bach notated his organ works on only two staves, usually with the soprano clef above the bass. 2] While the fugue is in G minor, the key signature contains only one flat. It was common practice in the Baroque period and earlier to notate music in the minor mode with a key signature of one flat less than we use today. This is known as the ‘Dorian’ key signature. Bach’s Toccata and Fugue in D minor [the so-called ‘Dorian’] has no flats in the key signature. Interestingly, in the Peters edition, the G minor fugue has a modern key signature while the Dorian adheres to the original. The one-flat key signature works as well for G minor as the modern two-flat version: Bach writes the flat symbol when E flat is required, and writes nothing when he needs E natural. In the modern signature, a natural sign needs to be written before E when that pitch occurs, but nothing is necessary when E flat is intended. It is a perfect illustration of the old saying ‘six of one, a half dozen of the other. 3] In the 4th measure, Bach rewrites the flat symbol in the 1st repeated group of 16th notes. This is the case in subsequent statements of the fugue’s subject in the home key of G minor and in several other instances throughout the piece. 4] Both the 1st and 2nd systems end with a half-measure, thus no bar line appears. 5] Two additional staff lines, rather than individual ledger lines, appear on the top staff toward the beginning of the 3rd system, and extra staff lines appear briefly in other places. 6] Bach often notates three voices on the upper staff alone, with crystal clarity. 7] The third entrance of the fugue subject, in the tenor, takes place on the 3rd beat of the 1st complete measure of the 2nd system, signifying an invisible shift of the bar line. The ‘displaced’ bar line shifts back to the notated downbeat when the bass voice enters in the last full measure of the 2nd system, where Bach writes in ‘Ped.’ The pedal begins a long rest in the last measure of the 3rd system, and does not return until the following page. 8] The prominent diminished 5th in the 2nd measure of the fugue subject is replaced by a perfect 5th later in the fugue, when the tonality shifts to the relative major.