Develop a musical composition based on the provided pattern of letters and incorporating the given motif within it.
X:1
L:1/8
M:2/4
K:A
['Ac Bc', 'f2 fa A2 Af ec']  
X:1
L:1/8
M:2/4
K:A
 Ac Bc | A>B Af | ec c/B/A/B/ | cB Bc/B/ | Ac Bc | A2 Af | ec Bc/B/ | A2 A :| f2 fa | A2 Af | 
 ec c/B/A/B/ | cB Be | f2 fa | A2 Af | ec Bc/B/ | A2 A :|  