Chen Yaozi, Duke Kang Su was unsurpassed in archery, and he had a very high opinion of himself.
One day, when he was shooting arrows in his own garden, an old oil peddler happened to pass by. The old man laid down his shoulder pole with its load, stood to one side, watched askance for a long while and didn't go away.
When the old man saw him hit the target every time, he didn't cheer, but only nodded slightly. Duke Kang Su asked:
"Do you know archery too? Isn't my skill excellent?"
The old man said:
"This is nothing, only skillful technique."
Duke Kang Su was angry and rebuked him loudly:
"How dare you belittle my archery skill?"
The old man replied unhurriedly:
"I know this from pouring oil."
As he spoke, he put a bottle gourd on the ground, and a copper coin with a hole in its centre on the mouth of the bottle gourd. Then he slowly poured oil into the bottle gourd with a ladle. The oil, like a thin string, went straight into the bottle gourd through the hole in the copper coin without staining the coin at all.
The old man smiled and said:
"This is nothing either, only skillful technique."