Once the Pandava princes were walking in a deep forest and got lost. Finally, after many hours of walking they became exhausted and thirsty, and decided to rest in the cool shade of a tree.
Yudhistira spoke to his youngest brother, "Nakula, we need water. Climb this tree and see if there is a river in sight." Nakula, although tired, climbed high up the tree. "Yes, I see a lake," he shouted, much to the relief of the others. "Good," Yudhisthira croaked, his throat parched with thirst. "Please could you fetch us some water?"
Nakula ran to the lake. He could almost taste the cooling waters refreshing his dry mouth. He knelt down, and was raising a palm full of water to his mouth, when a voice boomed out. "Stop! Do not take a drink until you have answered my question. I am the keeper of this lake. If you don't do as I say, then you will die." Completely exhausted, Nakula decided to ignore the voice. He took a gulp of the cool water and immediately fell down dead.
Meanwhile, the other Pandavas were waiting for what seemed like ages. Each minute made their thirst more desperate. So Yudhisthira begged another brother, "Sahadeva, could you please help Nakula bring back the water?" Sahadeva practically crawled to the lake, and was shocked to find his brother dead. But as his own throat was burning with thirst, he rushed to the waters edge.
Again the voice ordered him to stop. Sahadeva ignored the advice and scooped up a palmful of water. Like his brother, he dropped dead on the spot.
Yudhistera next sent Arjuna, and then some time later Bheema. Neither of them returned. Yudhisthira, now understanding something was terribly wrong, went himself. He could scarcely believe his eyes. The lifeless bodies of four powerful warriors lay scattered by the shore of the lake. How could they be killed so easily with no sign of a fight? He sank to his knees in grief. It was not possible for him to live without his faithful brothers. They had sacrificed so much to please him, and now they were gone forever. Then his own fierce thirst overcame his anguish, and he crawled towards the cool refreshing water.
"Stop!" a voice called out ominously. "You cannot drink this water until you have answered my questions. Heed this warning or you'll meet the same fate as your brothers." Yudhisthira stopped and, scanning the sky, replied, "I'll do as you request to the best of my ability. But before I do so, please show your self to me. I am astonished how a single person has the power to kill all four of my brothers. Bheema himself had the strength of ten thousand elephants. No man has the power to kill any one of my brothers." A mighty and frightening Yaksha, a magician, appeared before the prince. With respect, Yudhisthira joined his palms and bowed slightly before the sorcerer. "Thank you. Please ask me your questions."
"Your humility is charming," the Yaksha said. "Here is my first question: What is faster than the wind?"
Yudhisthira replied, "The mind of course."
The Yaksha rubbed his hands together. "Quite right. But do you know what the most valuable possession is?"
"That's also easy – it's knowledge?"
"But what is real knowledge?"
"True knowledge is knowledge of the divine."
"Now tell me what makes something agreeable only if it is given up?"
"It can only be pride."
"And what is wickedness?"
"Speaking ill of others."
"But do you know what charity is?"
"Giving protection to all creatures."
"What is patience?"
Yudhisthira drew his eyes away from the cool waters of the lake and tried to ignore the dryness in his throat. "Patience can only be the ability to control the senses."
"And my last question: What is the most wonderful thing in the world?"
Yudhisthira considered carefully before answering this final question. He glanced once again over at his dead brothers. With confidence he said. "Day after day living entities are dying. No one escapes it, but those remaining think that they will not die. Can there be anything more wonderful than this?"
The Yaksha smiled broadly. "I am satisfied by your intelligent answers, you are the wisest person and you deserve to take a boon from me. I will grant the life of one of your brothers. Please choose which one." After pausing to consider, Yudhisthira replied, "I choose Nakula."
"But why Nakula? Why not the mighty Bheema or Arjuna? They are surely more valuable to you?"
"My father had two wifes, Kunti and Madri. Bheema, Arjuna and I are Kunti's sons. So for Madri's benefit I choose Nakula."
Overjoyed at hearing such a selfless answer, the Yaksha brought all the dead brothers back to life and then revealed his true identity. "I am your father who you have never met. I am the God of death and the knower of what is right and what is wrong. I wanted to test your wisdom. I am proud that you answered so well. My son, because you are devoted to truth and righteousness, you will never know defeat."
Yudhisthira humbly fell down at his father's feet and wept tears of joy.