Construct an exceptional musical piece by incorporating Bach's distinguished 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 D | F F G G | A A _B A | G2 !fermata!F A, | F F G G | A A G F | E2 !fermata!D A | %7
 F G !fermata!E A | F G !fermata!E E | F F G G | A A G F | E2 !fermata!D z |] %12
V:2
 z3 A, | D/E/ F F E/D/ | C D D/ G F/ | F/E/4D/4 E !fermata!C A,/G,/ | F, D D C | C F F/ E D/ | %6
 D ^C !fermata!A, E | E/D/ D/E/ !fermata!^C E | D/C/ D C C | C D D E | E/D/4E/4 F E3/2 D/ | %11
 D ^C A, z |] %12
V:3
 z3 F, | A, C D C/_B,/ | A,/G,/ F,3/2 E,/ C | D/G,/ C/_B,/ !fermata!A, F,/G,/ | A, _B,3/2 A,/ G, | %5
 F, C C/>_B,/ A, | _B, A,/G,/ !fermata!F, A, | A, _B, !fermata!A, A, | A, G, G, G, | %9
 A, A, _B,3/2 C/4B,/4 | A, D/C/ _B, A, | _B, A,/G,/ ^F, z |] %12
V:4
 z3"Dm" D, |"Dm" D,"F/A" A,,"Gm7/Bb" _B,,"C" C, |"F" F,/E,/"Dm" D,"Gm7" G,,"Am" A,, | %3
"Gm7/Bb" _B,,"C" C,"F" !fermata!F,,"F" F,/E,/ |"Dm" D,/C,/"Bb" _B,,/A,,/"Gm" G,,/F,,/"C/E" E,, | %5
"F" F,,/G,,/"F/A" A,,/_B,,/"Csus4" C,"Dm" D, |"Em7b5/G" G,,"A" A,,"Dm" !fermata!D,,"A/C#" ^C, | %7
"Dm" D,"Gm" G,,"A" !fermata!A,,"Am/C" =C, |"Dm7/C" C,"G/B" =B,,"C" !fermata!C,"C" C,/_B,,/ | %9
"F/A" A,,/F,,/"Dm" D,/C,/"Gm/Bb" _B,,/A,,/"Edim/G" G,,/C,/ | %10
"F" F,/E,/"Dm" D,"Em7b5/D" D,/^C,/"Dm" D, |"Em7b5/G" G,,"A" A,,"D" !fermata!D,, z |] %12  