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
['ecA cde', 'A dfa agf efg eag f3 g3']  
X:1
L:1/8
M:6/8
K:D
 DFA dcd | ecA cde | f3 g3 | ecA GFE | DFA d3 | ecA cde | faf gzc | edc d2 A :| dfa agf | efg eag | 
 f3 g3 | ecA GFE | DFA dcd | ecA cde | faf gec | edc d3 :|  