Compose a piece of music that follows both the given musical theme and the letter-based structure provided.
X:1
L:1/8
Q:1/8=180
M:6/8
K:D
['d2 d']  
X:1
L:1/8
Q:1/8=180
M:6/8
K:D
|: A | d2 d cBA | B2 B AGF | GAG FED | EFG ABc | d2 d cBA | B2 B AGF | EFG ABc | d3- d2 d | 
 f2 e def | e2 d cde | d2 c Bcd | c2 B A2 d | f2 e def | e2 d cde | dcB e2 ^G | A3- A2 :|  