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
['GBdg dBcA BG', 'G,2 (g/a/b) eg (f/g/a) df e/f/g/f/ ed']  
X:1
L:1/8
M:4/4
K:G
 GBdg dBcA | BG cA BG cA | GBdg dBcA | BG AF G2 G,2 :: (g/a/b) eg (f/g/a) df | e/f/g/f/ ed ^cBAg | 
 f/g/a Ba ^cA Ag | fdec d2 D2 :|  