Section 30.8 Fugue Analysis
We will now turn to analysis of fugue. Let us set out definitions first.
A fugue is a contrapuntal composition whose form features sections called expositions and episodes.
A fugue exposition is a section that contains at least one full statement of the subject of the fugue. 1
The fugue subject is the primary melodic idea and is stated by each voice in turn in the first exposition.
The answer, called “response” in some texts, refers to the statement of subject in the key of the dominant by the second voice to enter in a fugue. Sometimes this statement of the answer has intervals altered in order to start in the tonic before modulating to the dominant. When the intervals are altered in this manner, we call this a “tonal answer.” In contrast, a “real answer” contains no alteration of intervals. In the example below, notice that the third note of the subject in measure 1 descends a perfect fourth to the fourth note. In the answer in measure 3, the third note descends a perfect fifth to the fourth note.
An episode is a section that does not contain a full statement of the fugue subject, but instead develops the subject or other prominent ideas through fragmentation and sequencing.
Here is the first exposition of Fugue 2 in C minor in Book I of the J.S. Bach’s Well-Tempered Clavier. In the first exposition of a fugue, all of the voices state the subject at least once. It is important to note that a answer is considered equivalent to a subject because the intervallic alterations are so minute.
The bridge, if it occurs, is a brief modulatory passage that only happens within the first exposition, usually to connect the answer to the subsequent subject statement.
A countersubject is counterpoint that consistently accompanies each occurrence of the subject. “Countersubject 1” is in the alto voice in measure 3 and in the soprano voice in measure 7. The alternative to using a countersubject would be for a composer to write different accompanying counterpoint (labeled as “CTRPT” in the examples) each time a subject is stated.
Within the bridge (bar 5 in the example above), we see motivic fragmentation of the subject (“subject head”). Subjects, answers, and countersubjects can be fragmented into head motives and tail motives in episodes in fugues. In this fugue, there is motivic fragmentation of the subject, countersubject 1, and countersubject 2.
Below is the first episode, which contains motivic fragmentation of the subject and countersubject 1.
Below are the second exposition, the second episode, the third exposition, and the third episode.
In the four systems below, we see the fourth exposition, fourth episode, and final exposition, which includes two subject statements separated by cadential material.
In homework and on the test, you will be asked to analyze a fugue with regard to expositions (including the bridge, if it occurs), episodes, subjects, answers, countersubjects, and motivic fragmentation.