Page:Fugue by Ebenezer Prout.djvu/83

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Chap. IV.]
Fugue.
65

Kirnberger.

 \new ChoirStaff <<
  \new Staff \relative a, { \clef bass \key a \minor \time 2/2 \partial 2 \mark \markup \tiny { (\italic"b") }
    a2^\markup \bold "S" | a c | b e | dis4 d cis c | b }
  \new Staff \relative e { \clef bass \key e \minor
    e2^\markup \bold "A" | e f | e a | gis4 g fis f | e } >>

152. Fugue subjects are sometimes answered by inversion. In this case the answer is not generally in the key of the dominant; but that species of inversion is used in which dominant is answered by tonic, and tonic by dominant (Double Counterpoint, §§ 281, 282). Sometimes the answer by inversion is given in the first exposition, as in Bach's 'Art of Fugue,' No. 5—

J. S. Bach. Art of Fugue, No. 5.

 \new ChoirStaff <<
  \new Staff \relative a' { \key d \minor \time 4/4
    a2^\markup \bold "S" d,4. e8 | f4. g8 a2 | bes2 a4. g8 |
    f2 ~ f8 e f g | a bes c4 ~ c8 bes a bes |
    e, f g4 ~ g8 a f g | a s s4_"&c." }
  \new Staff \relative d { \clef bass \key d \minor
    R1*3 | d2^\markup \bold "A" a'4. g8 | f4. e8 d2 |
    cis2 d4. e8 | f2 } >>

More frequently, however, this device is reserved for the later developments of the fugue, in order to heighten the interest, as in Nos. 15, 20, and 46, of the 'Wohltemperirtes Clavier.' An answer by inversion is much more common with a minor subject than with a major.

153. We also sometimes find answers by augmentation and diminution. In these again there is no need that the answer should be in the dominant key. The object of putting the answer in the dominant is to prevent its being a mere monotonous repetition of the subject; and this end is sufficiently attained either by inversion or by altering the lengths of the notes. In Nos. 6 and 7 of the 'Art of Fugue' will be seen examples, too long to quote here, of answers by augmentation and diminution.

154. Sometimes, especially in vocal fugues, in order to keep the answer in a more convenient compass, the change of an octave in pitch is made in the course of the answer, as in the following passage—

Schumann. Requiem.

 \new ChoirStaff <<
  \new Staff \relative f'' { \key f \minor \time 4/4 \partial 4
    f4^\markup \bold "S" ~ | f bes,8 c ees des r c |
    bes2 aes4 ees_"*" ~ | ees8. aes16 aes4 g8 ees r ees ~ |
    ees8. aes16 aes4 g8 ees }
  \new Staff \relative c'' { \key f \minor
    c4^\markup \bold "A" ~ | c f,8 g bes aes r g |
    f2 ees4 aes ~ | aes8. des16 des4 c8 aes r aes ~ |
    aes8. des16 des4 c8 aes } >>

A similar example, which is familiar to everybody, will be found in the "Amen" chorus of the 'Messiah.'