Craft a musical composition that adheres to the specified musical theme and letter-based structure.
X:1
L:1/8
M:4/4
K:Dmin
['d2 e2 f2 e2', 'defg a2 a2 dfed ^c2 A2']  
X:1
L:1/8
M:4/4
K:Dmin
|: d2 e2 f2 e2 | dfed ^c2 A2 | d2 e2 f2 e2 | defg a4 :: e2 (ef) g2 (ga) | g2 ^f2 g4 | 
 g2 (ga) g2 a2 | bagf e4 | defg a2 a2 | dfed ^c2 A2 | defg a2 a2 | dfed ^c2 A2 | a2 f2 bagf | 
 e3 d d4 :|  