Craft a piece of music that integrates both the suggested theme and letter-based structure.
X:1
L:1/4
M:2/2
K:C
['B A/G/ G A', 'g2 f2 e']  
X:1
L:1/4
M:2/2
K:C
 d | B A/G/ G A | c3 e | d2 B2 | c A2 d/c/ | B A/G/ G A | c2 c e/f/ | g2 f2 | e c2 :: e/f/ | 
 g2 f2 | e c c e | d2 B2 | c A2 d/c/ | B A/G/ G A | c3/2 d/ e c |{ef} g2 f2 | e c2 :|  