Compose a piece of music that follows both the given musical theme and the letter-based structure provided.
X:1
L:1/8
M:6/8
K:D
['dfa agf efd cBA Bcd efg fed', 'DFA DFA', 'G g2 f/e/', 'e2 d/c/']  
X:1
L:1/8
M:6/8
K:D
|: dfa agf | efd cBA | Bcd efg | fed cBA | dfaagf | efdcBA | Bgfedc | d3 D3 :: DFA DFA | EGB EGB | 
 DFA DFA | dcB AFD | DFADFA | EGBEGB | cedcAc | d3 d3 :|[M:2/4][K:G] G | G g2 f/e/ | ddd>c | 
 B/d/B/G/ A/c/A/F/ | GGG>G | G g2 f/e/ | d a2 g | fe/d/ A^c | ddd :: d | d =f e/d/ | ccc>c | 
 c e2 d/c/ | BBB>A | G g2 G/F/ | E e2 d/c/ | BA/G/ DF | G[GD][GG,] |]  