Utilizing the provided musical theme and letter-based structure, compose a piece of music.
X:1
L:1/8
M:4/4
K:C
['G2 Be d2 Bd', 'bagb a2 (fa)']  
X:1
L:1/8
M:4/4
K:C
[M:2/2][K:G] .abc G2 Be d2 Bd | gdBd cAFA | G2 Be d2 Bd | dcAB GDEF | G2 Be d2 Bd | gdBd cAFA | 
 GBAc (3Bcd eg | fdcA G3 z || | bagb a2 (fa) | gfeg (fd) d2 | bagb a2 (fa) | gfef d2 (ga) | 
 bagb a2 (fa) | gfeg fdBA | GBAc (3Bcd eg | fdcA G3 z |]  