| Book 2 - No. 18 - G sharp minor - Fugue | |||||
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Rhythmically, the subject and countersubject work "in between" one another. The 6/8 time signature works on two primary levels of grouping beats within a measure of six counts: two beats and three beats. On one level, the six counts fall into two groups with two strong accents, one, two, one, two. On another level, each of these two accented beats breaks into three subdivisions, one, two three, one, two, three. In between each beat, there are three sub beats. In between each group of three beats, there is a single strong beat. The subject works on the level of the three sub beats, evenly and steadily counting out six notes (two groups of three) per measure. The countersubject works primarily on the level of the two beats: its basic unit is the dotted quarter note representing the three sub beats as one large beat. It further subdivides this three-pulse into two uneven sub beats, a long beat (quarter note) and a short beat (eighth note). The subject is based on threes, the countersubject is based on twos. Rhythmically, they work "in between" on another.
The countersubject works "in between" elements of the subject in terms of its pitch pattern as well.. The subject spans a range of just over an octave: nine notes. It is strictly diatonic: it uses only the notes from the G-sharp minor scale. The countersubject spans a much smaller range, using only about five half-steps that fit well within the range of the subject, in between its boundaries. The countersubject is also chromatic: it uses notes outside the scale of G-sharp-minor, accidentals in between the standard notes.
On a broader level, like most fugues, this fugue provides an adventure by exploring what happens "in between" subject entries: in the episodes. While the subject and its entries serve as the chief focus of our attention, the figure standing out from the ground, this mode of perception is easily invertible so that the ground may appear to stand out from the figure. Patterns of subject entry and episode vary quite a bit from one fugue to another. In this fugue, subject entry and episode alternate (oscillate) quite regularly: there is an episode in between every pair of subject entries but the first.
This fugue is a double fugue: the second subject is introduced independently of the first with its own, undisturbed exposition. Following its exposition, all subsequent entries of the second subject are faithfully accompanied by the first subject: each subject becomes consistent counter material for the other. Counter motives against the first subject presage the character of the second subject: rhythmically and chromatically. As a double fugue, it presents first one subject, then another. The climax of a double fugue is when both subject combine, when we experience what happens "between" them as they occur simultaneously. It is curious to note that the second subject is much like the first countersubject, while the counterpoint to the second subject is much like the first subject. In a kind of role reversal, figure becomes ground, and ground becomes figure.
Finally, the penultimate note of the second subject is a trill. A trill is a fast oscillation between two notes, in this case, between the fifth degree of the scale (the dominant) and a note a half-step below it. A trill represents a sort of suspended resolution, a little tension filled drum roll that heightens the final resolution on a stable note following the trill. A trill revels in the indefinite space "in between" two notes.
In a non-related observation, notice that the first subject is a sequence, built from the simple repetition of a motive by moving it upward one step. Notice that its countersubject is also a two-unit sequence.