Musical Form
Fugue
A melodic idea, chased through the voices that follow it.
Form / Technique
A fugue is built from a single short melodic idea, called the subject, which is introduced by one voice alone and then imitated, in turn, by each other voice in the texture - each new entrance typically starting while the previous voices continue on with related material. The word comes from the Latin fuga, "flight" or "chase," which is a fair description of what it sounds like: one idea, pursued through the texture.
Fugues are the high point of counterpoint - the technique of combining multiple independent melodic lines so they work together harmonically. Writing a good fugue is often treated as a serious test of compositional craft, since the composer has to keep a single idea coherent and interesting across every voice simultaneously.
How a fugue works
A fugue usually has three, four, or more "voices" - independent melodic lines, whether sung by a choir or played by a keyboardist's two hands. The vocabulary is worth knowing:
- Exposition - the opening, where each voice enters with the subject in turn. The second entry, the answer, is usually the subject moved to a different key, a fifth higher or a fourth lower.
- Countersubject - a second melodic line that often accompanies the subject each time it appears, fitting against it like a puzzle piece.
- Episodes - freer passages between entries, built from fragments of the material, that carry the music through new keys.
- Stretto - entries that overlap, with a new voice starting the subject before the previous one has finished - a common way to build excitement toward the end.
Unlike sonata form, a fugue isn't a fixed template so much as a procedure: two fugues can be laid out very differently while following the same principles. A canon - think "Row, Row, Row Your Boat" - is a stricter cousin, in which each voice repeats the leader's line exactly.
Bach and the fugue
Johann Sebastian Bach is the composer most associated with the form - his Well-Tempered Clavier is a landmark collection pairing a prelude and fugue in every major and minor key, twice over. His organ fugues, and the fugal choruses of his Masses and Passions, show the same mastery on a grand scale, and his late The Art of Fugue explores a single subject in every way he could devise; it breaks off, unfinished, in the middle of a final fugue.
Fugues after Bach
The fugue never disappeared. Handel used fugal writing in many of the choruses of Messiah. Mozart crowned his "Jupiter" Symphony with a finale weaving five themes together in counterpoint, and Beethoven wrote some of the most ferocious fugues ever conceived, including the Grosse Fuge for string quartet. Verdi ended his final opera, Falstaff, with a comic fugue for the whole cast. In the 20th century, Béla Bartók opened his Music for Strings, Percussion and Celesta with a slowly unfolding fugue, and Shostakovich wrote a complete set of 24 Preludes and Fugues for piano in homage to Bach.
Famous fugues
- Bach - "Little" Fugue in G minor, for organ.
- Bach - Toccata and Fugue in D minor (attributed).
- Bach - The Well-Tempered Clavier - 48 preludes and fugues.
- Mozart - finale of Symphony No. 41, "Jupiter."
- Beethoven - Grosse Fuge, Op. 133.
- Shostakovich - 24 Preludes and Fugues, Op. 87.
Where to start listening: Bach's "Little" Fugue in G minor is a compact, clear example of the subject entering one voice at a time; listen for the same short melodic idea reappearing throughout. Then try any fugue from The Well-Tempered Clavier and count the entries as the voices come in.