Fugue

   A composition or a significant, self-contained portion of a larger composition, based entirely on imitation. The subject is announced unaccompanied:

   Most commonly, a single subject and its countersubject provide all the motivic material for the entire fugue; occasionally fugues may have multiple subjects (double fugue, etc.). A two-voice texture, the minimum, is rare; three and four voices are most common; five and six occasionally occur, especially in vocal music. Fugues are signifi-cant for sacred music in two ways: as a means of constructing choral numbers in masses, oratorios, cantatas, motets, etc.; and as organ repertory which may have a peripheral function, as prelude or postlude music, in Christian liturgy.

   The Latin word fuga ("flee") has been associated since the early 15th century with imitative composition in various genres: popular song, round, catch, canon, motet, fantasia, ricercar, canzona. But while some of those terms could include other textures, fuga came to be associated exclusively with imitative texture by the 17th century. In modern usage it generally applies to music dating from the late 17th century or later.

   There is no traditional form for fugues, but there are many conventional terms (see figure 2). An exposition of the fugue presents a complete subject, or entry, in any voice, whereas an episode works with material derived from the exposition. A stretto (It. "tightened") is an exposition in which the entries are overlapped more quickly than originally.

   The acknowledged master of the keyboard fugue, and in particular those for organ that might have been heard in church, is Johann Sebastian Bach. His cantatas, passions, masses, and motets also contain many choral fugal movements, but in this application of fugal technique he is joined in mastery, although of a more dramatic, less religious kind, by his contemporary George Frideric Handel, whose English oratorios inspired many choral fugues of Franz Joseph Haydn and those of later composers of oratorios. In fact, after the 18th century the choral fugue was an essential component of the sacred musical semantic; no serious sacred oratorio or mass could do without one.

   

   Figure 2. Fuga from BWV 547, mm. 1-3.