Once Guru Nanak happened to visit Hardwar town.
There he saw some people throwing handfuls of water from river Ganges, towards
the sun in the east. They believed that by this ritual they could offer water to their
dead elders in the next world.
Guru Nanak went into the river and started throwing water towards the west.
As those people saw the Guru acting strange, they forgot their ritual.
They flocked to the Guru and laughed at his funny action. They asked him,
"Why are you throwing the holy water to the wrong side?"
The Guru calmly replied, "I am watering my withering crops in Punjab."
"Are you crazy? How can your water reach hundreds of miles away from here?"
asked the curious spectators.
"The very same way as yours reaches your ancestors in the other world. In fact,
my farm is quite closer on this very earth." Nanak replied.
This made those people think about the uselessness of their ritual.
How effective and rational a way to get people's attention and remove their ignorance!