Before creating a time-line you will need to analyze your fugue. The following questions and techniques are intended to facilitate such an analysis. A thorough and accurate analysis will save time and effort when you come to the time-line phase of the CD Counterpoint Companion. This document contains many links to the Anatomy of a Fugue that you might find helpful to have read first.
How many sections are there and in which measures do these sections begin and end?Analytical Technique: look for cadences.
Not every cadence represents the end of a section, but every section ends in a cadence.
Sections typically cadence in keys that are closely related to the home key. Closely-related keys differ by no more than one sharp or flat.
In the context of the 18th century fugue, authentic cadences (V-I) predominate, half (?-V) and deceptive (V-vi) cadences appear less often, and plagal cadences (IV-I) appear seldom.
Fugal cadences are difficult to recognize because the composer does not pause on the cadence chord; contrapuntal and harmonic motion normally continues directly into the next section. Cadences are often elided (the cadence chord serves dual function of concluding one section and beginning the next).
What is the function of each section?Analytical Technique: determine if the section exposes, develops, or concludes material.
Exposition: Analytical Technique: mark all instances where the main idea is stated or answered.
Because the exposition "exposes" new material, all fugues begin with an exposition. In the sense that it consists of the subject stated and answered in all voices, the exposition is the most predictable and form-defining section of the fugue. The subject (or answer) may appear in any order, but in Bach's fugues the bass voice will often take the last entry.
When the subject is answered in a second voice, the first voice may continue with a countersubject. Note all instances of countersubject.
Fugues may have more than one exposition. To qualify as an exposition the subject must appear in all voices and in the prescribed subject/answer relationship (tonal or real). In a re-exposition, the prior subject is voiced in the same order; in a counterexposition, the prior subject is voiced in a different order. A "double exposition" consists of the exposition of a second subject (triple-exposition = third subject, etc.)
Sections that elaborate upon the subject by contrapuntal means are called "developmental episodes." While the primary function of a development is to elaborate upon the subject, developments often contain statements of the fugue's subject outright, and these subjects are often answered.
Concluding Sections: Analytical Technique: listen for sections that sound as if they are bringing things to a close.
A section that concludes an interior exposition or development is called a "codetta." Codettas sound as if they are appended after the structural close of a main section. Codettas seldom last more than two or three bars.
More common is the "coda," which designates the conclusion of the entire fugue. Codas often modulate to the key of the subdominant. Codas often contain stretti, often visit the subject one last time (usually in the bass voice), and often employ pedal point.