Compose a piece of music that follows both the given musical theme and the letter-based structure provided.
X:1
L:1/8
M:4/4
K:G
['dGcB Aceg']  
X:1
L:1/8
M:4/4
K:G
 G2 (3GED, GFGA | BGcG dGcB | Aceg fdBA | (3cBA, GA GFED | GG (3AGE, DEGA | BABc dGcB | Aceg fdef | 
 (3gaB ad ga' (3gdB, | G2 (3GED, GFGA | BGcG dGcB | Aceg fdBA | (3cBA, GA GFED | GG (3AGE, DEGA | 
 BABc dGcB | Aceg fdef | (3gaB ad g2 ga |]  