Utilizing the provided musical theme and letter-based structure, compose a piece of music.
X:1
L:1/8
Q:1/8=180
M:4/4
K:G
['BAAc BGdG', 'dgbg agbg']  
X:1
L:1/8
Q:1/8=180
M:4/4
K:G
 BGdG eGdG | (3BBG dG BAAc | BGdG eGBd | egfa gedc | BGdG (3eeG dG | BGdG BAAc | BGdG (3eeG Bd | 
 egfa g4 || dgbg agbg | dgbg ag (3efg | dgbg agbg | abag edeg | dgbg agbg | dgbg agea | 
 (3bag (3agf gfed | egfa gedc ||  