The History Of Herodotus Volume 2 of 2
Page: 6174. After this Cleomenes, since it had become known that he had devised evil against Demaratos, was seized by fear of the Spartans and retired to Thessaly. Thence he came to Arcadia, and began to make mischief 62 and to combine the Arcadians against Sparta; and besides other oaths with which he caused them to swear that they would assuredly follow him whithersoever he should lead them, he was very desirous also to bring the chiefs of the Arcadians to the city of Nonacris and cause them to swear by the water of Styx; for near this city it is said by the Arcadians 63 that there is the water of Styx, and there is in fact something of this kind: a small stream of water is seen to trickle down from a rock into a hollow ravine, and round the ravine runs a wall of rough stones. Now Nonacris, where it happens that this spring is situated, is a city of Arcadia near Pheneos..
75. The Lacedemonians, hearing that Cleomenes was acting thus, were afraid, and proceeded to bring him back to Sparta to rule on the same terms as before: but when he had come back, forthwith a disease of madness seized him (who had been even before this somewhat insane 64), and whenever he met any of the Spartans, he dashed his staff against the man's face. And as he continued to do this and had gone quite out of his senses, his kinsmen bound him in stocks. Then being so bound, and seeing his warder left alone by the rest, he asked him for a knife; and the warder not being at first willing to give it, he threatened him with that which he would do to him afterwards if he did not; until at last the warder fearing the threats, for he was one of the Helots, gave him a knife. Then Cleomenes, when he had received the steel, began to maltreat himself from the legs upwards: for he went on cutting his flesh lengthways from the legs to the thighs and from the thighs to the loins and flanks, until at last he came to the belly; and cutting this into strips he died in that manner. And this happened, as most of the Hellenes report, because he persuaded the Pythian prophetess to advise that which was done about Demaratos; but as the Athenians alone report, it was because when he invaded Eleusis he laid waste the sacred enclosure of the goddesses; 65 and according to the report of the Argives, because from their sanctuary dedicated to Argos he caused to come down those of the Argives who had fled for refuge from the battle and slew them, and also set fire to the grove itself, holding it in no regard..
76. For when Cleomenes was consulting the Oracle at Delphi, the answer was given him that he should conquer Argos; so he led the Spartans and came to the river Erasinos, which is said to flow from the Stymphalian lake; for this lake, they say, running out into a viewless chasm, appears again above ground in the land of Argos; and from thence onwards this water is called by the Argives Erasinos: having come, I say, to this river, Cleomenes did sacrifice to it; and since the sacrifices were not at all favourable for him to cross over, he said that he admired the Erasinos for not betraying the men of its country, but the Argives should not even so escape. After this he retired back from thence and led his army down to Thyrea; and having done sacrifice to the Sea by slaying a bull, he brought them in ships to the land of Tiryns and Nauplia..