Craft a musical composition that adheres to the specified musical theme and letter-based structure.
X:1
L:1/4
Q:1/8=370
M:3/4
K:C
['[dG,,G,] e d [BG,,G,] G [BG,,G,]']  
X:1
L:1/4
Q:1/8=370
M:3/4
K:C
 z2 [dG,,G,] | [dG,,G,] e d | [BG,,G,] G [BG,,G,] | [dG,,G,] e d | [BG,,G,] G [BG,,G,] | 
 [dG,,G,]3 | [eC,,C,]2 [C,,C,] | [cA,,A,]3/2 B/ c | [AD,,D,]2 [cD,,D,] | [cD,,D,] d c | 
 [AD,,D,] ^F [AD,,D,] | [cD,,D,] B A | [eD,,D,]2 [D,,D,] | [dG,,G,] d d | [dC,,C,]2 [cC,,C,] | 
 [BD,,D,]3/2 A/ B | [GG,,G,]3 |]  