page_title: Fugue
section_title: Exposition
hierarchical_section_title: Fugue / Musical outline / Exposition
caption_attribution_description: English: Example of a tonal answer in a fugal exposition. This is from the exposition of J.S. Bach's Fugue no. 16, in G minor, BWV 861, from The Well-Tempered Clavier, Book 1. It has been typeset in Lilypond from the Bach Gesellschaft Edition (1866), and is in the public domain. Español: Ejemplo de una respuesta tonal en una exposición fugada. Esta imagen corresponde a la exposición de la Fuga número 16 en Sol menor (BWV 861) extraído del libro 1 de la obra El Clave Bien Temperado de Juan Sebastián Bach. Ha sido extraído de la Edición original de 1886 y es de dominio público.
context_page_description: In music, a fugue is a contrapuntal compositional technique in two or more voices, built on a subject that is introduced at the beginning in imitation and which recurs frequently in the course of the composition. It is not to be confused with a fuguing tune, which is a style of song popularized by and mostly limited to early American music and West Gallery music. A fugue usually has three main sections: an exposition, a development and a final entry that contains the return of the subject in the fugue's tonic key. Some fugues have a recapitulation.
  In the Middle Ages, the term was widely used to denote any works in canonic style; by the Renaissance, it had come to denote specifically imitative works. Since the 17th century, the term fugue has described what is commonly regarded as the most fully developed procedure of imitative counterpoint.
  Most fugues open with a short main theme, the subject, which then sounds successively in each voice; when each voice has completed the subject, the exposition is complete. This is often followed by a connecting passage, or episode, developed from previously heard material; further "entries" of the subject then are heard in related keys.
context_section_description: A fugue begins with the exposition of its subject in one of the voices alone in the tonic key. After the statement of the subject, a second voice enters and states the subject with the subject transposed to another key (usually the dominant or subdominant), which is known as the answer. To make the music run smoothly, it may also have to be altered slightly. When the answer is an exact copy of the subject to the new key, with identical intervals to the first statement, it is classified as a real answer; if the intervals are altered to maintain the key it is a tonal answer.
  A tonal answer is usually called for when the subject begins with a prominent dominant note, or where there is a prominent dominant note very close to the beginning of the subject. To prevent an undermining of the music's sense of key, this note is transposed up a fourth to the tonic rather than up a fifth to the supertonic. Answers in the subdominant are also employed for the same reason.
  
  While the answer is being stated, the voice in which the subject was previously heard continues with new material. If this new material is reused in later statements of the subject, it is called a countersubject; if this accompanying material is only heard once, it is simply referred to as free counterpoint. 
   The countersubject is written in invertible counterpoint at the octave or fifteenth. The distinction is made between the use of free counterpoint and regular countersubjects accompanying the fugue subject/answer, because in order for a countersubject to be heard accompanying the subject in more than one instance, it must be capable of sounding correctly above or below the subject, and must be conceived, therefore, in invertible (double) counterpoint.
  In tonal music, invertible contrapuntal lines must be written according to certain rules because several intervallic combinations, while acceptable in one particular orientation, are no longer permissible when inverted. For example, when the note "G" sounds in one voice above the note "C" in lower voice, the interval of a fifth is formed, which is considered consonant and entirely acceptable. When this interval is inverted ("C" in the upper voice above "G" in the lower), it forms a fourth, considered a dissonance in tonal contrapuntal practice, and requires special treatment, or preparation and resolution, if it is to be used. The countersubject, if sounding at the same time as the answer, is transposed to the pitch of the answer. Each voice then responds with its own subject or answer, and further countersubjects or free counterpoint may be heard.
  When a tonal answer is used, it is customary for the exposition to alternate subjects (S) with answers (A), however, in some fugues this order is occasionally varied: e.g., see the SAAS arrangement of Fugue No. 1 in C Major, BWV 846, from J.S. Bach's Well-Tempered Clavier, Book 1. A brief codetta is often heard connecting the various statements of the subject and answer. This allows the music to run smoothly. The codetta, just as the other parts of the exposition, can be used throughout the rest of the fugue.
  The first answer must occur as soon after the initial statement of the subject as possible; therefore the first codetta is often extremely short, or not needed. In the above example, this is the case: the subject finishes on the quarter note (or crotchet) B♭ of the third beat of the second bar which harmonizes the opening G of the answer. The later codettas may be considerably longer, and often serve to (a) develop the material heard so far in the subject/answer and countersubject and possibly introduce ideas heard in the second countersubject or free counterpoint that follows (b) delay, and therefore heighten the impact of the reentry of the subject in another voice as well as modulating back to the tonic.
  The exposition usually concludes when all voices have given a statement of the subject or answer. In some fugues, the exposition will end with a redundant entry, or an extra presentation of the theme. Furthermore, in some fugues the entry of one of the voices ma
caption: Example of a tonal answer in J.S. Bach's Fugue No. 16 in G Minor, BWV 861, from the Well-Tempered Clavier, Book 1. About this soundListen (help·info) 
   The first note of the subject, D (in red), is a prominent dominant note, demanding that the first note of the answer (in blue) sound as the tonic, G.
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