Utilizing the provided musical theme and letter-based structure, compose a piece of music.
X:1
L:1/4
Q:1/4=120
M:3/4
K:G
['G A', 'd d']  
X:1
L:1/4
Q:1/4=120
M:3/4
K:G
 G G A | F3/2 G/ A | B B c B3/2 A/ G | A G F | F G2 :| d d d | d3/2 c/ B | c c c | c3/2 B/ A | 
 B c/B/A/G/ | B3/2 c/ d | e A2 | F G2 |]  