Utilizing the provided musical theme and letter-based structure, compose a piece of music.
X:1
L:1/8
M:6/8
K:D
['cAd BGd AAG', 'FAA def']  
X:1
L:1/8
M:6/8
K:D
 g | fAd cAd | BGd AAG | F.A.A def | g3 eag | f2 d cAd | BGd AAG | F.A.A def | gec d2 e | 
 f2 d cAA | BGG AAG | FAA def | g3 eag | fdd cAd | BGd AAG | F2 A def | gec d2 A || FAA BAA | 
 FAD DAG | FAA def | g3 eag | f2 d cAd | BGd AAG | FAA def | gec d2 A | DAA BAG | FAD D3 | 
 DAA def | g3 eag | f2 d cAd | BGd AAG | FAA def | gec d2 ||  