A man knocked on a door.
"Who's there?" Asked God.
"Me." Replied the man.
"Go away then." Said God.
The man left and wandered in the arid desert until he realized his error. He returned to the door and knocked again.
"Who's there?" Asked God.
"You." Replied the man.
"Then come in," said God, "there's no room here for two."

Sufi teaching story.