Craft a piece of music that integrates both the suggested theme and letter-based structure.
X:1
L:1/8
M:4/4
K:G
['', 'ba gfge B2 ed cBcA E2 AG', 'g2 b2 g2']  
X:1
L:1/8
M:4/4
K:G
 ba |: gfge B2 ed | cBcA E2 AG | FGAB cdef | ga ge d2 ba | gfge B2 ed | cBcA E2 AG | FGAB cdef |1 
 g2 b2 g2 ba :|2 g2 b2 g2 Bc |: dBgB dgBc | (3dcB gB d2 cB | cafa cfAB | (3cBA fA c2 Bc | 
 dBgB dgBc | (3dcB gB d2 cB | cAbg fdef |1 g2 b2 g2 Bc :|2 g2 b2 g2 ba ||  