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 treble 
%%MIDI program 0
%%MIDI control 7 100
%%MIDI control 10 64
L:1/8
V:4 bass 
%%MIDI program 0
%%MIDI control 7 100
%%MIDI control 10 64
V:1
 z3 A/B/ | c B/A/ ^G A/B/ | c B !fermata!A c | d d e c | d d !fermata!e e | f e/f/ g/f/ e | %6
 d/c/ d !fermata!c e | c d c B | A ^G !fermata!A2 |] %9
V:2
 z3 E | A/G/ F E E/^G/ | A ^G !fermata!E A | =G/A/ B c E | A/c/ B/A/ !fermata!^G A | A/B/ c d c | %6
 B/ c B/ !fermata!G B | A A/^G/ A G | A/F/ E !fermata!E2 |] %9
V:3
 z6 CD | E2 DC B,2 CD | EF B,E !fermata!C2 E2 | D2 G2 G2 A2 | A2 D/E/F !fermata!B,2 C2 | %5
 D2 G,2 G,2 G2 | FE FD !fermata!E2 E2 | E2 D2 E2 ED | C2 B,^C/D/ !fermata!C4 |] %9
V:4
 z3"Am" A,, |"Am" A,"Bdim/D" D,"E" E,/D/"Am/C" C/B,/ |"Am" A,/D,/"E" E,"Am" !fermata!A,,"Am" A, | %3
"G/B" B,"G" G,"C" C/B,/"Am" A,/G,/ |"Dm/F" F,/E,/"Bdim/F" F,"E" !fermata!E,"Am" A, | %5
"Dm" D,"C" C,"G/B" B,,"C" C, |"G7" G,"Gm" G,"C" !fermata!C,"E/G#" ^G, | %7
"Am" A,/A,,/"Bm" B,,"Am/C" C,/D,/"E" E,, |"F" F,,/D,,/"E" E,,"A" !fermata!A,,2 |] %9  