After Lakshmana's death, Rama went to the river every day and wept for his brother.
There was also a monk who came to the river. Rama saw him fill his watering can and then pour the water over a large rock. The monk did this every day.
"That rock is not a plant," Rama told him. "It can't grow or produce fruit. So why do you water the rock?"
"Why do you shed tears for your brother?" replied the monk.
Rama then understood that his weeping served no more purpose than watering a rock, and he set his grief aside.