The Idiot in the Great City

One time a certain idiot arrived in a very great city and was confused by the number of people in the streets. He became afraid that if he slept and woke again he would not be able to find himself among so many people, so he tied a gourd to his ankle for identification.
Nearby, a practical joker watched what he had done and after waiting until he was asleep removed the gourd and tied it around his own leg.
He then laid down on the caravanserai floor to sleep. The idiot awoke first and, upon seeing the gourd tied to the other man's ankle, thought that this other man must be him, and began attacking the other while shouting: "If you are me, then for heaven's sake, who am I and where am I?"

from Tales of the Dervishes by Idries Shah