|Book 1 - No. 2 - C minor - Fugue|
Where the first fugue in the Well-Tempered Clavier revels in the subject and the thrill of its own juxtaposition in stretto, this second fugue features a common and important focus for attention beyond the subject: a countersubject. It is easily recognizable due to its own integrity and persistence throughout the fugue. Through its perfect rhythmic contrast, it stands out clearly and independently without obscuring the subject it compliments. Like most countersubjects, it appears as soon as it can: against the second subject entry in the exposition. The first statement of the countersubject is the continuation of the first voice after it completes the subject. While any voice in a fugue is active, but not stating the subject, it must form a complimentary counterpoint to the other voices in the polyphonic texture. Where the contrapuntal pattern forms a distinctly recognizable theme that recurs throughout the fugue, it warrents the importance of being named a countersubject.
This fugue also uses another aspect of fugue composition absent from the first fugue in C-major: the episode. Most fugues feature stretches of music where the subject is not heard. Occurring between subject entries, these are known as episodes. In addition to providing contrast to the subject, creating a space where the absence of the subject is noticable so that the anticipation of the next subject entry creates a heightened tension, episodes provide new contrapuntal textures with compelling musical content all their own. As is common, the episodic material in this fugue is derived from the exposition: the first 5-note motive of the subject as well as the scale passage in the countersubject.
This is the first fugue in the Well-tempered Clavier in a minor key or in the minor mode in general. Bach treats you to a lovely contrast when the subject enters briefly in the major mode (the relative major of C-minor, E-flat major). Though the fugue is almost entirely cast a the dark, minor key, it ends with a bright closure. Typical of many Baroque compositions in a minor key, it ends with a major triad where the minor third degree of the scale is raised a half a step. This is technically known as a Picardy Third and is generally peculiar to music no later than the Baroque.
Shostakovich had his own eloquent reaction to this fugue.