Craft a musical composition that adheres to the specified musical theme and letter-based structure.
X:1
L:1/8
M:4/4
K:Emin
['E2 GB', 'eBgf eBfe dAFA DE (3FED']  
X:1
L:1/8
M:4/4
K:Emin
 E2 GB E2 GB | A2 FA DE (3FED | E2 GB E2 GA | B_BBc BAGF | E2 GB E2 GB | A2 FA DE (3FED | 
 (3EFG (3FGA (3GAB (3ABc | BAFG E4 || eBgf eBfe | dAFA DE (3FED | eBgf eBBA | B_BBc BAGF | 
 eBgf eBfe | dAFA DE (3FED | (3EFG (3FGA (3GAB (3ABc | BAFG E4 ||  