Reading Guide. This is a spectacular episode in the epic, one of the most famous incidents. The original contains a whole long list of riddles which you can see here if you are curious to read more of them: Book 3: Vana Parva CCCXI (Ganguli translation).
Source. Indian Myth and Legend by Donald A. Mackenzie (1913). [700 words]
When the twelfth year of exile was nigh to an end, the Pandava brethren bethought them to leave the forest. But before they went a strange and dread adventure threatened them with dire disaster. It chanced that a stag carried away upon its antlers the twigs with which a brahmin was wont to kindle his holy fire. The brahmin appealed to Yudhishthira to pursue the animal, and the Pandavas endeavored in vain to kill it or recover the sacred twigs. Weary with the chase, they at length sat down to rest. They were all athirst, and one of them climbed a banyan tree to look for signs of water, for birds ever flutter over pools. When it was discovered that a pond was nigh, Yudhishthira sent Nakula towards it. The young man approached the water, and before he stooped he heard a Voice which said, "Answer thou what I shall ask of thee before thou dost drink or draw water."
But Nakula's thirst was greater than his fear, and he drank of the waters; then he fell dead.
Sahadeva followed him, wondering why his brother tarried. He too gazed greedily upon the pool, and he too heard the Voice, but heeded not and drank, and he fell dead also.
Arjuna next went towards the water. The Voice spake to him, and he answered with anger, "Who art thou that wouldst hinder me thus? Reveal thyself, and mine arrows will speak to thee."
Then he drew his bow, and his shafts flew thick and fast as raindrops. But his valor was as naught, for when he drank he also fell dead like the others. Bhima followed him, and stooped and drank, unheeding the Voice, and he was stricken down like to Arjuna and Nakula and Sahadeva.
At length wise Yudhishthira approached the pond. He beheld his brethren lying dead, and sorrowed over them. Then, as he drew nigh to the water, the Voice spake once again, and he answered it, saying, "Who art thou?"
The Voice said, "I am a yaksha. I warned thy brethren not to drink of this water until they had answered what I should ask of them, but they disregarded my warning and I laid them in death. If thou wilt answer my questions thou canst, however, drink here nor be afraid."
Said Yudhishthira, "Speak and I will answer thee."
The Voice said, "Who maketh the sun to rise? Who keepeth him company? Who maketh the sun to go down? In whom is the sun established?"
Said Yudhishthira, "Brahma maketh the sun to rise; the gods accompany him; Dharma maketh the sun to set; in truth is the sun established."
The Voice said, "What sleepeth with open eyes? What moveth not after birth? What is that which hath no heart? What is that which swelleth of itself?"
Said Yudhishthira, "A fish doth sleep with open eyes; an egg moveth not after birth; a stone hath no heart; a river swelleth of itself."
The Voice said, "What maketh The Way? What is called Water? What is called Food? What is called Poison?"
Said Yudhishthira, "They that are pious make The Way; space is called water; the cow is food; a request is poison."
The Voice said, "Who is spoken of as the unconquered enemy of man? What is spoken of as the enemy's disease? Who is regarded as holy? Who is regarded as unholy?"
Said Yudhishthira, "Man's unconquered enemy is anger, and his disease is covetousness; he who seeketh after the good of all is holy; he who is selfishly cold is unholy."
The Voice said, "Who are worthy of eternal torment?"
Said Yudhishthira, "He who sayeth unto the brahmin whom he hath asked to his house, I have naught to give; he who declareth the Vedas to be false; he who is rich and yet giveth naught to the poor."
Many such questions did the Voice address to wise Yudhishthira, and he answered each one patiently and with knowledge. Then the yaksha revealed himself in the form of Dharma, god of wisdom and justice, for behold! he was the celestial sire of Yudhishthira. Unto his son he granted two boons, and Yudhishthira desired that his brethren should be restored to life, and that they should all have power to remain unrecognized by anyone in the three worlds for the space of a year.