Compose a piece of music that follows both the given musical theme and the letter-based structure provided.
X:1
L:1/8
Q:1/8=160
M:4/4
K:G
['GABc d2 cd edcd B2 ba', 'g2 fg']  
X:1
L:1/8
Q:1/8=160
M:4/4
K:G
"^brilliant" BA | GABc d2 cd | edcd B2 ba | g2 fe B2 ^d2 | e4 B2 A2 | GABc d2 cd | edcd B2 ba | 
 gfed B2 ^d2 | e6 || ba | b3 a g2 fg | agfe d2 ef | g2 fg efga | b2 B2 B2 BA | GABc d2 cd | 
 edcd B2 ba | gfed B2 ^d2 | e8 |]  