Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
M:4/4
K:Emin
['E2 GE', 'B2 eB fBgB']  
X:1
L:1/8
M:4/4
K:Emin
 E2 GE AEBE | E2 GE cEGE | D2 DE FDFG | AGFD GFED | E2 GE AEBE | E2 GE cEGE | D2 DE FDFG | 
 AGFD E3 z :| B2 eB fBgB | B2 eB fBgB | A2 dA eAfA | gAfA edBA | B2 eB fBgB | B2 eB fBgB | 
 A2 dA eAfA | gfed e3 z :|  