Develop a musical composition based on the provided pattern of letters and incorporating the given motif within it.
X:1
L:1/4
Q:1/2=100
M:4/4
K:D
['A d', 'g e']  
X:1
L:1/4
Q:1/2=100
M:4/4
K:D
 D2 F A | d f a f | g e d c | d f A d | D2 F A | d f a f | e c A c | d2 D2 :| A2 c e | g e f d | 
 g e f d | e c B A | d2 a f | d c A =c | B g e c | d2 D2 :|  