Compose a piece of music that follows both the given musical theme and the letter-based structure provided.
X:1
L:1/8
Q:1/2=100
M:4/4
K:G
['G2 BG', 'D e dfdB AGAB dgBg AG E2']  
X:1
L:1/8
Q:1/2=100
M:4/4
K:G
 D | G2 BG AGBG | DGBG AGEA | G2 BG cBAB | GAGE D/D/D D :: e | dfdB AGAB | dgBg AG E2 | 
 de/f/ gB AGAB | GAGE DD/D/ D :|  