Develop a musical composition based on the provided pattern of letters and incorporating the given motif within it.
X:1
L:1/8
M:4/4
K:Amix
['eAcA eAcA', 'eaag eAcA']  
X:1
L:1/8
M:4/4
K:Amix
 eAcA eAcA | eAcA dBGB | eAcA eAcA | dBGB A2 A2 :| eaag eAcA | egge dBGB | eaag eAcA | 
 dBGB A2 A2 :|  