Devise a musical masterpiece using Bach's signature techniques.  
X:1
T:Music21 Fragment
T:Music21 Fragment
T:Music21
C:Music21
%%score 1 2 3 4
L:1/4
M:4/4
K:C
V:1 treble 
%%MIDI program 0
%%MIDI control 7 100
%%MIDI control 10 64
V:2 treble 
%%MIDI program 0
%%MIDI control 7 100
%%MIDI control 10 64
V:3 bass 
%%MIDI program 0
%%MIDI control 7 100
%%MIDI control 10 64
V:4 bass 
%%MIDI program 0
%%MIDI control 7 100
%%MIDI control 10 64
V:1
 z3 E | A G F E | D2 !fermata!E B | c c B/A/ B | !fermata!A3 E | A G F E | D2 !fermata!E B | %7
 c c B/A/ B | !fermata!A3 c | B/A/ G A B | c2 !fermata!c G | A G F F | !fermata!E3 =c | %13
 B/c/ d c B | A2 !fermata!B E | F E D G | !fermata!E3 z |] %17
V:2
 z3 C | C C C/D/ D/C/ | C B, !fermata!C D | C/D/ E E3/2 D/ | !fermata!C3 C | C C C/D/ D/C/ | %6
 C B, !fermata!C D | C/D/ E E3/2 D/ | !fermata!C3 E | D/F/ E/D/ C F | F E/D/ !fermata!E E | %11
 F E E D | !fermata!^C3 D | D D E/^F/ G | G ^F !fermata!G C/B,/ | A,/B,/ C C/A,/ B, | %16
 !fermata!C3 z |] %17
V:3
 z3 G, | F, G, A,/G,/ G, | A, G, !fermata!G, ^G, | A, A, A, ^G, | !fermata!A,3 G, | %5
 F, G, A,/G,/ G, | A, G, !fermata!G, ^G, | A, A, A, ^G, | !fermata!A,3 A,/G,/ | %9
 F,/A,/ C/B,/ A,/G,/ F,/G,/ | A, G,/F,/ !fermata!G, C | C _B, A, A, | !fermata!A,3 A, | %13
 G, A, G,/A,/ B,/G,/ | E D !fermata!D G, | F, G, G, G, | !fermata!G,3 z |] %17
V:4
 z3"C" C, |"F" F,"C/E" E,"F/A" A,,/B,,/"C" C, |"Dm7/F" F,,"G" G,,"C" !fermata!C,"G#dim/B" B,, | %3
"Am" A,,/B,,/"Am/C" C,/D,/"Esus4" E,"E" E,, |"Am" !fermata!A,,3"C" C, | %5
"F" F,"C/E" E,"F/A" A,,/B,,/"C" C, |"Dm7/F" F,,"G" G,,"C" !fermata!C,"G#dim/B" B,, | %7
"Am" A,,/B,,/"Am/C" C,/D,/"Esus4" E,"E" E,, |"Am" !fermata!A,,3"Am" A,, | %9
"Bdim/D" D,"C/E" E,"F" F,/E,/"Bdim/D" D, |"F/C" C,2"C" !fermata!C,"C" C, | %11
"F" F,/E,/"Em7b5/D" D,/^C,/"Dm" D,/E,/"Dm/F" F,/G,/ |"A" !fermata!A,3"D7/F#" ^F, | %13
"G" G,"D/F#" ^F,"F#m7b5/E" E,"G/D" D, |"A7/C#" ^C,"D" D,"G" !fermata!G,,"C" =C, | %15
"Dm" D,"C/E" E,/F,/"Gsus4" G,"G" G,, |"C" !fermata!C,3 z |] %17  