说苑/常摐有疾，老子往問焉，曰：「先生疾甚矣，無遺教可以語諸弟子者乎？

Do you have no instructions to leave for your disciples?” Chang Zong said, “I would have spoken to you even if you hadn’t asked.” Then he said, “Getting down from one’s carriage when passing by one’s old home district—do you know what that means?” Laozi said, “Getting down from one’s carriage when passing by one’s old home district—doesn’t that mean ‘not forgetting old friends’?” “Ah, you have it!” said Chang Zong.

Then he said, “Hurrying when passing by a lofty tree—do you know what that means?” Laozi said, “Hurrying when passing by a lofty tree—doesn’t that mean ‘respecting your elders’?” “Ah, you have it!” Chang Zong said.

Then he opened his mouth wide and showed it to Laozi, saying, “Is my tongue still there?” “Yes,” said Laozi.

“Are my teeth still there?” Chang Zong asked.

“They are gone,” said Laozi.

“Do you know what that means?” Chang Zong asked.

Laozi said, “Is it not true that the tongue survives because it is soft, and the teeth perish because they are hard?” “Ah, you have it,” said Chang Zong.

“You understand everything in the realm.

What need is there to speak further?