A fugue is a chase: one subject flees through many voices
From Latin fuga—“flight” or “escape”—a fugue is imitative counterpoint for two or more voices built on a subject that enters in imitation and keeps returning. Baroque composers treated it as proof of mastery; Bach remains its emblem, though Mozart, Beethoven, and Shostakovich still wrote them.
Typical layout: exposition, development with middle entries, and a final tonic return, often with episodes, stretto (overlapping subjects), or a coda. Medieval usage meant any canonic work; by the Renaissance, imitation specifically; since the seventeenth century, fugue names the fullest imitative procedure. English fugue arrived in the sixteenth century via French or Italian fuga, from Latin linked to fugere (flee) and fugare (chase). A fughetta is a small fugue; fugato is fugal texture inside another form.
Exposition starts with the subject alone in the tonic. A second voice answers—usually in the dominant (sometimes subdominant)—as a real answer (exact transposition) or tonal answer (tweaked intervals, often to protect the key when a dominant note opens the subject). Accompanying lines may become a reusable countersubject in invertible counterpoint, or remain free counterpoint. Voices alternate subject and answer, sometimes linked by brief codettas; Bach’s C-major Well-Tempered Clavier Fugue No. 1 (BWV 846) uses an unusual SAAS order.
Episodes modulate and fragment material—André Gedalge taught they often imitate broken subject bits—before middle entries in related keys. Bach often moves first to the relative major or minor. Subjects may invert, run retrograde, diminish, or augment. The form grew from ricercars, canzonas, and fantasias; Bach studied Sweelinck, Frescobaldi, Pachelbel, Buxtehude, and others. As sonata style rose, fugue’s centrality faded, yet study pieces persisted into the twentieth century.
Because composers choose so much structure freely, fugue sits closer to a technique than a rigid mold.
Source: Fugue
