They stopped there and Wise Man told one of his disciples, "I am thirsty. Do get me some water from that lake there."
The disciple walked up to the lake. When he reached it, he noticed that right at that moment, a bullock cart started crossing through the lake. As a result, the water became very muddy, very turbid.
The disciple thought, "How can I give this muddy water to Wise Man to drink!"
So he came back and told Wise Man, "The water in there is very muddy. I don't think it is fit to drink."
After about half an hour, again Wise Man asked the same disciple to go back to the lake and get him some water to drink. The disciple obediently went back to the lake.
This time too he found that the lake was muddy. He returned and informed Wise Man about the same.
Wise Man looked at the water and then he looked up at the disciple and said, "See what you did to make the water clean.