[8] At Thebes, when the battle was lost, Arion quickly spirited his master Adrastus away from the battlefield, saving his life, when all the other leaders of the expedition were killed.
[9] Arion is mentioned as early as in the Iliad of Homer, where he is described as the "swift horse of Adrastus, that was of heavenly stock.
"[10] A scholiast on this line of the Iliad explains that Arion was the offspring of Poseidon, who in the form of a horse, mated with Fury (Ἐρινύος) by the fountain Tilphousa in Boeotia.
[12] A poetic fragment of Callimachus (third century BC) says: Apesas is a hill near Nemea, and the line perhaps refers to Arion being raced during the first Nemean Games.
[15] The mythographer Apollodorus (first or second century), says that Poseidon sired Arion on the goddess Demeter, when "in the likeness of a Fury she consorted with him".
Apollodorus also says that, in the war of the Seven against Thebes, while all the other leaders of the Argive army were killed, only Adastus survived, "saved by his horse Arion".
[16] The second-century geographer Pausanias, by way of explaining why at Thelpusa in Arcadia, they call Demeter "Fury", gives a more complete account of the birth of Arion.