A frog lived in a small well(井). He said to a turtle(乌龟) who lived in the East Sea, "I am so happy! When I go out, I jump out of the well. When I come home, I rest in the holes on the broken wall of the well. If I walk in the mud(泥土), it will cover up my feet. I look around here, and no one can compare with me. I am the owner of this well. My dear sir, why don't you come over and look around my place?"
Then the turtle told the frog about the East Sea.
"You have no idea how large and how deep the sea is. In the past thousands of years, there were floods(洪水)for many years, the water in the sea didn't become less. The sea does not change with time and it does not rise or fall as the rain falls, either. The greatest happiness is to live in the East Sea."
There is always someone better than you; there is always something greater than you know. So everyone should be humble.