Craft a musical composition that adheres to the specified musical theme and letter-based structure.
X:1
L:1/4
M:3/4
K:G
['d B G', 'D/G/ B/d/ B']  
X:1
L:1/4
M:3/4
K:G
 d/4d/4d/ | e d B | G A G | E G E | D3 | G B e | d B G | A3 | A2 d/4d/4d/ | e d B | G A G | E G g | 
 e3 | d B G | A E F | G3 | G2 z || D/G/ B/d/ B | D/G/ B/d/ B | E/G/ c/e/ c | E/G/ c/e/ c | 
 D/G/ B/d/ B | D/G/ B/d/ B | D/F/ A/c/ A | D/F/ A/c/ A | D/G/ B/d/ B | D/G/ B/d/ B | E G g | e3 | 
 d B G | A E F | G3 | G2 ||  