Bodhidharma meditate facing the wall

One of the disciples of Bodhidharma came to him, and Bodhidharma had told him, "Become completely empty and silent, only then come to me." The disciple worked for years. Then he became empty, silent. Then he came to Bodhidharma and said, "Now, Master, I have come, and you had told me 'Be silent and empty'. Now I have become silent and empty." Bodhidharma said to him, "Go out and throw this emptiness and silence also."