Page:Fugue by Ebenezer Prout.djvu/73

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Chap. IV.]
Fugue.
55

C, is the third of the tonic, and is answered by the third of the dominant; the second E is not followed by a note of the tonic chord, and is therefore regarded as sixth of the dominant. Our next example,

J. S. Bach. Cantata, "Singet dem Herrn ein neues Lied."

 \new ChoirStaff <<
  \new Staff \relative d { \clef bass \key d \major \time 3/4 \mark \markup \tiny { ( \italic b ) }
    d4^\markup \bold "S" d d | e e e |
    fis8 a16 g fis8 e16 fis gis8 fis16 gis | a4 }
  \new Staff \relative a { \clef tenor \key d \major
    a4^\markup \bold "A" a a | b b b |
    cis8 e16 d cis8 a16 b cis8 b16 cis | d4 } >>

illustrates a different point. The first F in the third bar cannot be regarded as belonging to the dominant key, because of the G natural that follows, neither can the second which resolves the preceding G; but the F preceding the G sharp is treated as the submediant of A.

131. The same principles will guide us in dealing with the leading note. Let the fundamental principle be thoroughly grasped that the tonal change must be made as soon as possible, and the whole thing is easy. If a subject modulates, the leading note must be always treated as the third of the dominant, and answered by third of tonic, except when it is merely an auxiliary note of the tonic to which it at once returns, e.g.

J. S. Bach. Wohltemperirtes Clavier, Fugue 2.

 \new ChoirStaff <<
  \new Staff \relative c'' { \key c \minor \time 4/4
    r8 c16 b c8 g aes c16 b c8 d |
    g,8 c16 b c8 d f,16 g aes4 g16 f | ees }
  \new Staff \relative g'' { \key c \minor
    r8 g16 fis g8 c, ees g16 fis g8 a |
    d, g16 fis g8 a c,16 d ees4 d16 c | bes } >>

This subject does not modulate, but it shows the use of the leading note as an auxiliary note.

132. The following examples

J. S. Bach. Organ Fugue in C.

 \new ChoirStaff <<
  \new Staff \relative c' { \key c \major \time 4/4 \mark \markup \tiny { ( \italic a ) }
    c4^\markup \bold "S" ~ c16 b c d e8 c a fis' | g4 }
  \new Staff \relative g { \clef bass \key c \major
    g4^\markup \bold "A" ~ g16 e f g a8 f d b' | c4 } >>


J. S. Bach. Wohltemperirtes Clavier, Fugue 18.

 \new ChoirStaff << \override Score.Rest #'style = #'classical
  \new Staff \relative g { \clef bass \key gis \minor \time 4/4 \mark \markup \tiny { ( \italic b ) }
    r4^\markup \bold "S" gis4 fisis8 gis16 ais b8 ais |
    gis cisis dis fis, gis gis ais ais | dis, }
  \new Staff \relative d' { \key gis \minor
    r4^\markup \bold "A" dis4 bis8 cis16 dis e8 dis |
    cis fisis gis b, cis cis dis dis | gis, } >>