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:D
['Bd A2 BdA>f', 'f2 g>eTfd']  
X:1
L:1/8
M:4/4
K:D
 d>ef>d Bd A2 | BdA>f e>def | d>eTfd Bd A2 | BdA>f e2 d2 :| d>efg ad f2 | g>eTfd e>dBe | 
 d>efg a<d f2 | g>eTfd e2 d2 | defg a>d f2 | gafa e>dBe | dfeg faga | afg>f e2 d2 ||  