|Book 1 - No. 11 - F major - Fugue|
The subject is, itself, like a complete song: the melody lilts about four core descending notes, with pauses, motives, direction and closure. It describes a complete musical period. The melody implies the complete harmony IV-I-V-I. The major modality is bright. The character is happy, musical delight. But this little nested song, a humble fugal subject, is but the stem cell of an extraordinary higher-level structure.
Modality? Music of the "common" or "traditional" Western period (circa 1600-1900 and ongoing in the majority of popular music) is based on an essential polarity between two "modes": major and minor. A mode is a scale, a finite selection of tones that form a vocabulary for musical utterance. While there are theoretically many modes, many different combinations of tones, two have predominated musical expression for many hundreds of years: major and minor. The mode directly influences the melodic and harmonic possibilities of a musical piece. The most immediate as well as profound experience of this effect can be summarized as mood. Music in the major mode is, to simplify, happy, bright, positive. Music in the minor mode is sad, dark, negative. These are crude but useful terms for the extremes. In the case of music with the eloquence, the nuance and the sophistication of Bach, you will find an indescribable palette of moods that result from rich melodic and harmonic possibilities within each mode and the skillful transition between modes over time. Music articulates time not only so that you feel a static emotional state, but the movement into and out of these states as well. The mood waxes and wanes, returns again with greater force or profundity or perhaps even diminishes in final defeat to a new, more significant outlook. Numerous facets of music combine synergistically to create these effects: tempo, rhythm, dynamics, etc. But the essential emotional color of music has so much to do with modality.
This fugue is compelling, among other reasons, for its dynamic modality. First, light, joyous, major. Eventually, dark, sorrowful, minor. The shift to minor is further punctuated by the tension of stretto. Does the fugue shift back to major again? Is it the "same" major as before, or somehow deepened, informed by the minor interlude?
The key signature of one flat is used for both a major and a minor mode: F major (this fugue) and D minor. The next fugue is also in F, but F minor. You can learn more about these relationships by looking at the circle of 5ths. Comparing and contrasting these fugues on the basis of modality alone is a rich and rewarding way to hear them. It highlights an essential quality of our Western earsense.