The exposition is the opening ritual of a fugue — all voices enter with the subject in turn. After the exposition, episodes (without the subject) and middle entries (subject returns) alternate, building toward the climactic stretto.
The Exposition
The exposition of a fugue is the section in which each voice enters with the subject (or answer) in order. In a three-voice fugue, the order might be: soprano enters with the subject; alto enters with the answer (a fifth lower or fourth higher); bass enters with the subject (now an octave below the soprano's opening). After all three voices have entered, the exposition is complete. The order of entries is not fixed — Bach uses many different sequences across his fugues — but the principle is constant: each voice must enter with subject or answer, and after all voices have entered the exposition concludes.
During the exposition, each voice that has already stated the subject or answer continues with the countersubject (if there is one) or with free counterpoint — melodic material that harmonises with the answer being stated by the next voice. The exposition establishes the key, introduces all the primary melodic material, and demonstrates the fugue's texture. It is typically 3-4 measures per voice; a four-voice fugue exposition is therefore roughly 12-16 measures long.
Episodes
After the exposition, the fugue enters its development phase, consisting of alternating middle entries (returns of the subject in various keys) and episodes (transitional passages without the subject). Episodes typically use sequential patterns derived from the subject or countersubject material, often employing invertible counterpoint — the same two-voice texture appearing in reversed order, at a new pitch level, or in modified form.
The episode is the fugue's breathing space: a moment of harmonic movement (often moving toward a new key area for the next subject entry) that provides contrast with the density of subject entries. Bach's episodes are often the most beautiful and harmonically adventurous passages of his fugues. They typically:
- Use sequential repetition — a 1-2 measure pattern transposed up or down by step or third several times in succession.
- Modulate toward a new key — the relative major or minor, the dominant, or sometimes a more distant key for dramatic effect.
- Develop motivic fragments from the subject — perhaps the head motive (first few notes) or the tail motive (last few notes) in isolation.
- Employ invertible counterpoint so that the same material can appear in different voicings within a single episode.
- Lead seamlessly into the next subject entry, with the final notes of the episode anticipating the harmonic preparation needed for the new entry.
Middle Entries
Middle entries are subject statements that occur after the exposition, typically in keys other than the tonic. The progression of keys through the middle entries forms the fugue's harmonic plan — a movement away from the tonic, exploration of related keys, and eventual return. A typical key plan for a fugue in C major might be: exposition in C major; first middle entry in G major (dominant); second middle entry in A minor (relative minor); third middle entry in E minor or D minor; return to C major for the final entries. The order is not fixed, but the principle of harmonic adventure followed by return is constant.
Middle entries may use the subject in original form, in inversion (every interval reversed in direction), in augmentation (note values doubled), or in diminution (note values halved). Bach's Art of Fugue is essentially a study of these subject transformations: each contrapunctus explores a different transformation or combination.
Stretto
Stretto (from the Italian for "narrow" or "tight") is a special technique in which successive entries of the subject are compressed — each entry begins before the previous one has finished. The result is overlapping layers of the same subject, creating an intensification of polyphonic density. Stretto appears most commonly near the end of a fugue, where it builds maximum contrapuntal tension before the final cadence.
The ability to write stretto requires that the subject be designed from the outset to harmonise with itself in overlapping entries — a compositional planning requirement that Bach handles with apparently effortless mastery. Not every subject will support stretto; if the subject's harmonic implications are incompatible with delayed self-imitation, stretto is impossible. The greatest stretto fugues in the literature include Bach's C major fugue from WTC Book I (BWV 846), the D-sharp minor fugue from WTC Book I (BWV 853), and many of the contrapuncti from the Art of Fugue.
The Pedal Point and Final Section
Fugues typically end with a final entry in the home key (often with a pedal point — a sustained bass note, usually the tonic or dominant, while the upper voices continue above it), followed by a coda or final cadence. The pedal point creates a moment of harmonic suspension: the bass holds while the upper voices may pass through dissonances against it, generating a feeling of inevitable arrival at the cadence.
The last chord is usually a major triad even in minor-key fugues — the tierce de Picardie (Picardy third), a Renaissance tradition of ending on a major chord to signal finality. The minor-key C-sharp minor fugue from WTC Book I (BWV 849) ends on C-sharp major; the F minor fugue from Book I (BWV 857) ends on F major; almost every minor-key fugue in the WTC ends with this characteristic gesture of brightening to major at the final cadence.
Analysing a Complete Fugue
A complete fugue analysis should map the entire piece into its constituent sections. Identify the exposition (subject and answer entries in order); identify each middle entry by voice, key, and measure; identify each episode by its starting and ending measures and its sequential or developmental character; identify any stretto passage; identify the pedal point if present; and identify the final cadence. The resulting analytical map shows the architecture of the fugue at a glance and reveals how Bach (or any other fugal composer) shapes the dramatic arc from opening exposition to final cadence.
Sources and Further Reading
- Gauldin. A Practical Approach to 18th-Century Counterpoint. Waveland Press. Chapters 11-13.
- Kennan. Counterpoint. Prentice-Hall. Chapters on Fugue Development.
- Open Music Theory — Fugue (openmusictheory.net, CC BY-SA 4.0).
- IMSLP — Bach WTC complete (imslp.org).
- Aldwell and Schachter. Harmony and Voice Leading. Schirmer/Cengage.