Craft a musical composition that adheres to the specified musical theme and letter-based structure.
X:1
L:1/8
Q:1/4=160
M:2/4
K:C
['c2 eg fedc BGAB Tc3 d ecac', 'g4 gfeg af Tf2 fedf ge Te2']  
X:1
L:1/8
Q:1/4=160
M:2/4
K:C
 c2 eg | fedc | BGAB | Tc3 d | ecac | dBgB | A2 T^f2 | g4 :: gfeg | af Tf2 | fedf | ge Te2 | edcd | 
 cagf | e2 Td2 | c4 :|  