The informant is recounting a Chinese proverb from home. He does not remember where he heard it.
“Constant dripping wears away the stone.”
He interprets this to emphasize the importance of perseverance.
That this is a widespread proverb interesting is interesting due to the connection to the popular legend of Chinese water torture. As the legend has it, the Chinese would torture prisoners by slowly dripping water on their foreheads. This could be a literal interpretation of this proverb.