Shih-tou Hsi-chien (700-790) was a very well known Chinese Ch'an master.
As a young monk, he was one of the disciples of the Sixth Patriarch Hui-neng.
After Hui-neng passed away, Shih-tou continued his pilgrimage...
He paid a vist to the Great master Hsing-szu at the Ching-yuan mountain.
-Where did you come from?
-From Tsao-chi [referring where Hui-neng resided].
-What did you get at Tsao-chi?
-Before I was at Tsao-chi, I was not lacking anything.
-If so, why were you there?
-If I were not there, how could I know I did not lack anything?