One of the most popular pieces among piano lovers, Bach's Prelude in C major (BWV 846) is also a prelude to the Well-Tempered Clavier as a whole. It started out life as an exercise for Bach's son Wilhelm Friedemann Bach:
This manuscript is in the hand of the young Wilhelm Friedemann, except for the final four measures and the two chords at the bottom (circled), which are in Johann Sebastian Bach's handwriting. The chordal notation in the final measures is clearly a notational shorthand—the pattern is intended to be continued to the end of the piece. (This version of the Prelude in C major is listed in the Bach Werkverzeichnis—the official catalog of Bach's works—as BWV 846a, the 'a' designating that it is a version of the C major Prelude from Book 1 of the Well-Tempered Clavier.)
Here is the sheet music for free download:
I'm including a performance of mine, which I played on a beautiful Bösendorfer model 225 grand piano. My intention is not to uphold my interpretation as somehow exemplary, but simply to offer one example of how the Prelude in C major might be played on a modern piano:
You might notice that I refrain from the kind of exaggerated articulation that Glenn Gould made famous, unless my legato playing of each chord may be considered exaggerated. My personal aesthetic position is that professional classical musicians have considerable responsibility for playing stylistically: It's our duty to understand internal musical expressive grammar—the expressive syntax common to all tonal music regardless of when it was written—as well as style that can only be gleaned from familiarity with contemporary documents. In the case of Baroque music, sound recording was invented fully a century and a half too late for us to have any actual recordings of Baroque musicians from which to make any stylistic inferences; we have to make due with early textbooks and other such instruction manuals, which lend us a misleading idea of historical accuracy at best.
Purists will—no doubt rightly—scoff at my liberal use of the pedal. After all, Bach's harpsichord had no sustain pedal, so why use it? My answer is simply that the piece sounds more beautiful on the modern piano with pedal. Anyone wanting to be truly "authentic" in Bach should avoid the piano altogether, as do most advocates of historical performance, since it is so different from the instruments of Bach's time (including the early Silbermann fortepiano which Bach praised). Personally, I find literal attempts to apply harpsichord-style articulation—whether it be historically accurate or not—to the modern piano unconvincing. I prefer to avail myself of the expressive resources of the modern piano, being well-schooled in Bach's articulation. (My teacher Paul Badura-Skoda wrote a nearly 600-page book called Interpreting Bach at the Keyboard.)
For the record, I am very much an advocate of historical performance. However, my notion of "historical" differs quite radically from its common usage. In short, I don't believe that our primary task as performers of classical music is to interpret "texts," i.e., black dots on a white page, and that early textbooks are our primary means for doing so. This is an infinitely long discussion, and I am clearly getting ahead of myself. I'll save my explication of my aesthetics for other articles.
Returning to Bach's Prelude in C major, it is important to grasp what may be called closed harmonic phrases. There is no real melody to the prelude, just arpeggiated chords. The ear needs to accomplish two things simultaneously: First, we must grasp, and shape (both rhythmically and dynamically on the piano), the phrases that are formed by the chords. These are measures 1-4, then 5-11, 12-19, and 20 through the end of the prelude. Hearing chords as blocks of sound played simultaneously is what is known as vertical listening.
Second, the ear must follow the voice leading—the individual voices that change from one harmony to the next. This is called horizontal listening. A strong dissonance in one chord, such as the minor second B-C in the bass in measure 8, will resolve in the next measure (the B resolves downward to A in measure 9).
Interestingly, the most effective way to practice both vertical and horizontal listening in the C major Prelude is to practice in block chords, playing all of the notes of one measure simultaneously. Such practice will give you a "bird's eye view" of the music. You will doubtless find it easier to shape the harmonic movement, which you can then apply to your playing of the prelude as written. For instance, when playing in block chords it can be immediately heard that measure 2 is stronger than measure 1, and that the natural stress then decreases to the resolution back to C major in measure 4. Measures 1 through 4 thus form a closed harmonic unit, a phrase.
I hope this miniature lesson on Bach's Prelude in C major from Book 1 of the Well-Tempered Clavier proves useful in your practicing! Download the sheet music from this link, and be sure to have a look at other free sheet music on offer from key-notes.