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
['BegB gagf', 'gagf Beeg', 'Beed edBd egfd', 'BedB fBeB']  
X:1
L:1/8
M:4/4
K:Emin
 B3 e gBeg | BegB gagf | AdfA fgfd | fgfd Adfd | BegB gagf | gaag- gfef | gagf fgfd | Beed e3 || 
 f | gagf Beeg | fgfd Adfd | gagf Beeg | Beed efed | gagf Beeg | fgfd Adfd | gagf fgfd | Beed e3 || 
 d | Beed edBd | egfd ed B/c/d | A2 d/d/d dBAB | dABd ABdA | Beed edBd | egfd edBd | gagf fgfd | 
 Beed e3 || d | BedB fBeB | fBef Befe | AdfA gAfA | gAfA gfed | BedB fBeB | fBeB fBeB | gagf fgfd | 
 Beed e3 ||  