These two pieces always strike me as appropriate opening works.
The prelude is unusual. It’s unquestionably written for organ — the very first thing we hear is an open octave in the bass that holds for two measures (which is a long time for a piece that is only 34 measures long), and long, held notes feature prominently throughout. The structure is something of a proto-sonata form. Although it is in a simple ABA form (unlike the neatly packaged [A:||BA:||] rounded binary form most typically associated with early sonata form), a substantial amount of material is clearly restated in two different harmonic areas, separated by a highly chromatic, quasi-developmental few bars. To me, the most logical way to perceive the form of the piece is the following:
Introduction — Core Material — Development — Recapitulation of Core Material — Coda.
The overall harmonic movement supports this view, as well. The first time we encounter that “core material,” we are moving away from the tonic and into the expected dominant and secondary dominant key areas. The second time we encounter it, we are in the process of moving back to the tonic. While the prelude is relatively short and obviously doesn’t have the entire weighty structure of what we consider a “true” sonata form, it is interesting to consider that some of the core characteristics of this form — the development and moment of recapitulation — were starting to appear in earlier music.
The fugue loosely pairs with the prelude. The two pieces are clearly related in character (i.e. stately, introductory), but I don’t see deeper musical connections (e.g. shared musical ideas) between them. The fugue is tricky in a certain kind of way. It’s fast, with a fairly long subject. At the same time, because Bach doesn’t employ many advanced contrapuntal techniques (e.g. stretto, augmentation, etc.), this fugue is more straight-forward than many others.
For me, the most challenging aspect was the mental/technical aspect of keeping the constant mini-scales clean-sounding and accurate. A lot of the fugue is similar, but just different enough. It took a fair amount of trial and error to figure out how to focus my attention in a way that kept the various permutations straight. This challenge was particularly true during the sequences — where the same material is repeated several times, each time a step higher (or lower, but in this case we almost always get ascending sequences, which helps create mounting excitement).
Sequence: the same material is repeated one step higher several times. From this vantage point, things look pretty straightforward; it is a…different experience on the piano bench.
The running sixteenth notes maintain their particular pattern (until they don’t), and each iteration feels slightly different because of different configurations of black and white notes. Combined with the relatively fast tempo, it was difficult to keep track of everything at speed.
I found that while some slow practice was helpful for thinking through everything, it was not the most effective practice strategy. Instead, I found playing one hand alone while “ghost-playing” the other hand’s part, with a metronome, at about a performance tempo (and then switching so both hands received the opportunity to be both a ghost and a real player) was the most helpful tool. This method allowed me to narrow my focus onto one hand’s task, while testing my auditory/musical memory of other parts.
In general (but especially for this piece), true hands-alone practice, especially in larger chunks, tends to be a little misleading. I have often found myself in the situation where I’ll practice, for example, the left hand alone and it will sound great in isolation, but I’ll find that nothing has really improved after I recombine it with the other material. By incorporating the physical movements of both hands while only audibly hearing one, I get a much more realistic picture of what each hand is actually sounding like at any given time.