A traveller was making his long journey home, when one day he saw a terrifying monster behind him. He turned to confront the monster, but it disappeared.
Every day, at the same time of the day, the traveller would see this monster, and each time he would turn to fight it, but to no avail.
He asked each fellow traveller if they had seen such a monster, and all said they did not.
The monster was slowly driving the traveller crazy with its antics, each and every day.
One day, the traveller stopped and asked a Rabbi, if he could see the monster…
The Rabbi replied, but pointed out that the traveller was walking alongside a white sand wall, and that each day the Sun would cast his shadow, reaching a maximum cast at the same time each day.