Develop a musical composition based on the provided pattern of letters and incorporating the given motif within it.
X:1
L:1/4
M:3/4
K:G
['E C']  
X:1
L:1/4
M:3/4
K:G
 D | G3/2 F/ G | E C E | D E C | B,2 D | B G B | A F A | G F E | D2 D/D/ | B G B | A F A | G F E | 
 F2 D | G3/2 F/ G | E C E | D G F | G2 ||  