fugues

A fugue is a musical composition based on the systematic imitation of a single melodic idea, the subject. The form is a type of contrapuntal writing in which the subject is stated in one voice and then enters successively in other voices, often with a countersubject and with close attention to rhythm and key relationships. Fugues can be written for keyboard, voices, or ensemble.

A typical fugue proceeds through an exposition, episodes, and entries. In the exposition, the subject is presented in turn by each voice, usually starting in one voice and then answered or imitated in another at a different pitch. After the exposition, episodes—sections that derive material from the subject or countersubject but do not restate the complete subject—provide modulation and development. Entrances of the subject may occur in close succession in a stretto, creating overlapping entries. Common devices include augmentation, diminution, inversion, and retrograde, as well as the use of a countersubject that accompanies the subject in some voices.

Fugues reached their apex in the Baroque era, with composers such as Johann Sebastian Bach writing extensive keyboard and vocal fugues. The form also appeared in organ works, concertos, and choral settings. Earlier roots can be traced to ricercares and canzonas of the late Renaissance and early Baroque; the term fugue derives from fuga, meaning flight in Latin, reflecting the rapid discovery and imitation of the subject.

Common types include simple fugues, double or triple fugues (two or three subjects heard simultaneously), and pedal-point fugues in which a voice holds a sustained note while the subject enters elsewhere. Later composers, including Beethoven in his Grosse Fuge, expanded the technical scope and emotional range of the form.

In music theory, the fugue is studied as a model of polyphonic development and is valued for its rigorous counterpoint and structural coherence. While most associated with Baroque keyboard music, fugue technique has influenced later classical forms and remains a topic of scholarly analysis and performance practice.