Theseus, whom Hercules was bent on freeing from his torment, had met and killed this robber-assassin, and Jupiter, for his sins, decreed that the malefactor should continually be rolling up a hill in Tartarus a heavy stone which, when with incredible pains he had brought nearly to the top, always rolled back again, and he had to begin over and over again the heart-breaking ascent.
Some distance from Sisyphus Hercules came upon Tantalus, who, in the flesh, had been King of Phrygia, but who now, weak from hunger and parched with thirst, was made to stand to his chin in water with branches of tempting luscious fruit hanging ripe over his head. When he essayed to drink the water it always went from him, and when he stretched out his hand to pluck the fruit, back the branches sprang out of reach.
In addition an immense rock, hung over his head, threatened every moment to crush him.
It is said that Tantalus, when in the flesh, had betrayed the secrets of the gods and also committed other great crimes. For this he was "tantalized" with food and drink, which, seeming always to be within his reach, ever mocked his hopes by eluding his grasp.
The groans of a crowd of disheveled women next attracted the affrighted attention of Hercules. They were forty-nine of the fifty daughters of Danaus, King of Argos, who, at the instigation of their father, had killed their husbands because Danaus thought they were conspiring to depose him.
One only of the fifty, to wit Hypermnestra, had the courage to disobey this unlawful command and so saved the life of Lynceus, her husband, with whom she fled. Later on Lynceus returned and slew the cruel King in battle.
To punish the forty-nine Danaides, Jupiter cast them into the outer darkness of Black Tartarus, where they were ever engaged in the hopeless task of pouring water into a sieve. Hypermnestra, on the contrary, was honored while alive, and also after her death, for loving goodness even more than she loved her father.
Glutted with horror Hercules at length quitted gloomy Tartarus and beheld in front of him still another river. This was Lethe. Whoso drank the waters of this river, which separated the place of torment from the abode of the blest, lost memory of all that had been aforetime in his mind, and so was no longer troubled by even the remembrance of human misery.