Compose a piece of music that showcases the essence of Bach's work.  
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 C | G E/D/ C G | A A !fermata!G G | A B c B | A A !fermata!G E | A G F E | D2 !fermata!C C | %7
 G E/D/ C G | A A !fermata!G G | A B c B | A A !fermata!G E | A G F E | D2 !fermata!C z | %13
 G2 !fermata!E2 | G2 !fermata!E2 | F E D E | F E D E | F E D2 | !fermata!C2 c B | A G F E | %20
 D2 !fermata!C z |] %21
V:2
 z3 G, | G, G, A, B, | E D D E | F F E D | D/E/ D/C/ B, C | C B, C/D/ E/C/ | C B, G, G, | %7
 G, G, A, B, | E D D E | F F E D | D/E/ D/C/ B, C | C B, C/D/ E/C/ | C B, G, z | D2 C2 | D2 C2 | %15
 D C B, C | D C B, C | D C/B,/ A,/B,/4C/4 B, | G,2 E ^D | E E/D/ C C | C B, G, z |] %21
V:3
 z3 E, | D, C,/D,/ E,/^F,/ G, | G, ^F, B, C | C D G, G, | G, ^F, G, G, | F,/E,/ D, A, G, | %6
 G,3/2 F,/ E, E, | D, C,/D,/ E,/^F,/ G, | G, ^F, B, C | C D G, G, | G, ^F, G, G, | %11
 F,/E,/ D, A, G, | G,3/2 F,/ E, z | G,2 G,2 | B,2 G,2 | A, G, G, G, | G, G, G, G, | %17
 A,/B,/ C C/A,/ G,/F,/ | E,2 A,/G,/ ^F, | E, B, A, G, | A, G,/F,/ E, z |] %21
V:4
 z3"C" C, |"G/B" B,,"C" C,"Am" A,,"Em" E, |"Am7/C" C,"D" D,"G" !fermata!G,,"C" C, | %3
"F" F,"Bdim/E" E,/D,/"C/E" E,/^F,/"G" G, |"Dsus4" D,"D" D,,"G" !fermata!G,,"C" C, | %5
"F" F,,"G" G,,"F/A" A,,/B,,/"C" C, |"Gsus4" G,,2"C" C,"C" C, |"G/B" B,,"C" C,"Am" A,,"Em" E, | %8
"Am7/C" C,"D" D,"G" !fermata!G,,"C" C, |"F" F,"Bdim/E" E,/D,/"C/E" E,/^F,/"G" G, | %10
"Dsus4" D,"D" D,,"G" !fermata!G,,"C" C, |"F" F,,"G" G,,"F/A" A,,/B,,/"C" C, |"Gsus4" G,,2"C" C, z | %13
"G/B" B,,2"C" C,2 |"G" G,,2"C" C,2 |"Dm" D,"C/E" E,"G7/F" F,/E,/"C/D" D,/C,/ | %16
"G7/B" B,,"C" C,"G" G,,/G,/"C/F" F,/E,/ |"Dm" D,"Am" A,,/G,,/"Dm7/F" F,,"G" G,, | %18
"C" C,2"Am" A,,"B" B,, |"A/C#" ^C,/^D,/"Em" E,"F/A" A,,/B,,/"C" =C, | %20
"D7/F#" ^F,,"G" G,,"C" !fermata!C, z |] %21  