Develop a musical composition based on the provided pattern of letters and incorporating the given motif within it.
X:1
L:1/8
M:3/8
K:G
['GBA G3', 'dc/B/A Bce d3 Bdc A3 ccc B/c/BG']  
X:1
L:1/8
M:3/8
K:G
|: GBA | G3 | BdB | dc/B/A | GBA | G3 | BdB | dc/B/A :: Bce | d3 | Bdc | A3 | ccc | B/c/BG | B2 A | 
 G3 :|  