The G-minor Adagio
The opening Adagio or Grave in all three solo sonatas is the prelude to the fugue that follows. Indeed, in the A-minor and C-major sonatas the opening Grave and Adagio are not even totally separate from their fugues because they end harmonically open. After a conclusive tonic cadence (m. 21, beat 3, in the A-minor Grave; m. 45, downbeat, in the C-major Adagio), additional music leads to an open-ended dominant chord. Even though the G-minor Adagio does in fact end with a strongly conclusive tonic cadence, it too forms a pair with the following fugue, not only because of musical connections between the movements (discussed in this and the next chapter) but also because Baroque-era fugues are almost always preceded by preludes of one sort or another—whether that preceding movement is called a preludio, a preambulum, a toccata, an adagio or grave, or something else.
Composers paired preludes and fugues for both aesthetic and practical reasons. Theorists in the Baroque period drew many of their images of musical structure from rhetoric—the art of verbal persuasion and the skill of organizing an argument to captivate an audience. In a well-made fugue, the composer coaxed the argument of an entire composition out of a single, often quite short, unaccompanied subject.
To do this effectively required mastery of difficult contrapuntal and compositional techniques. One could quip, “It’s hardly a great honor to compose a minuet,” as the student in a 1752 composition treatise brags at his first lesson.1 In fact, musicians of the time published methods by which amateurs could “compose” a minuet or other dance—that is, create characteristic melodic lines above simple chords—even if they were totally ignorant of music.2 No such methods existed to create a fugue’s web of independent parts that must project a musical idea if the result is to be more than a mere counterpoint exercise.