“Can you do this?” he asked the old oil peddler.
“No, I can’t.”
“What do you think of my skill?”
“Just OK, but nothing special. You’ve gained your accuracy from persistent practice. That’s all.”
“What can you do, then?”
The old man said nothing. He put a gourd bottle on the ground and covered its mouth with a copper coin. He then scooped out a ladle of oil from his big jar, held it high and began to fill the bottle. Now, a thread of oil came down from the ladle into the bottle just through the hole of the coin. Everybody looking on watched with amazement. But the old man said, “This is nothing special, I can do this because I have practiced it a lot.” And with these words, he left.
Later, people use this phrase to mean “Practice makes perfect”.