Craft a musical composition that adheres to the specified musical theme and letter-based structure.
X:1
L:1/8
Q:1/4=140
M:4/4
K:C
['d2 e2', 'z G G>AG>A B>cB>c d>ed>e f2 e>d']  
X:1
L:1/8
Q:1/4=140
M:4/4
K:C
 G | c2 c>c c2 e>d | c2 G2 c2 d2 | e2 e>e e2 g>f | e2 d2 e2 f2 | g2 g>g g2 a>g | f2 f>f f2 gf | 
 e2 dc g2 fe | d2 d>d d2 z :: G | G>AG>A B>cB>c | d>ed>e f2 e>d | c>dc>d e>fe>f | g>ag>a b2 ag | 
 afda gecg | f>ed>c B2 A>G | A>Bc>f e2 Td2 | c2 c>c c2 :|  