Kakua was the first of the Japanese to study Zen in China. In China he accepted the true teaching and did not travel while he was there. He lived on a part of a mountain and meditated constantly. Whenever he was confronted by people for teachings, he uttered a few words and moved to a different part of the mountain where he cannot be traced easily.
Kakua after returning to Japan was asked by the king to preach for edification and that of his subjects.
Kakua stood before the king in silence. He then pulled out a flute from the folds of his robe, blew one short note, bowed politely and disappeared. After that no one knew what had actually become of him.
The truth vanishes when uttered.