A disciple said to Lu Chü: “Master, I have attained to your Tao. I can do without fire in winter. I can make ice in summer.”

“You merely avail yourself of latent heat and latent cold,” replied Lu Chü. “That is not what I call Tao. I will demonstrate to you what my Tao is.”

Thereupon he tuned two lutes, and placed one in the hall and the other in the adjoining room. And when he struck the kung note on one, the kung note on the other sounded; when he struck the chio note on one, the chio note on the other sounded. This because they were both tuned to the same pitch.

But if he changed the interval of one string, so that it no longer kept its place in the octave, and then struck it, the result was that all the twenty-five strings jangled together. There was sound as before, but the influence of the key-note was gone.