One day, the master and his disciples took a walk in the park. They passed by a small pond that had fishes swimming to and fro.

“Look how happy the fish are as they swim around in the pond,” said the master.

A bystander nearby scoffed, “How do you know the fish are happy? You’re not a fish.”

“And how do you know that I don’t know that they’re happy?” countered the master, “You are not me.”