Nasrudin used to carry a box with some holes in it whenever he went to
the pub to drink. The bartender wondered what he was carrying in the
box. One day he asked Nasrudin. Nasrudin explained:
"Whenever I get drunk, I see snakes all around me. It is a very
frightening sight. So, I carry a mongoose in this box. With this box
near me, I do not get frightened."
The bartender told Nasrudin:
"What a fool you are !! There are no snakes here. They are all only
in your mind."
"I am not a fool. I know there are no snakes. There is no mongoose in
this box either. The mongoose is also only in my mind."