Passage 8.19.3
ὃς δʼ ἂν ὑπὸ κυνὸς κατασχέτου λύσσῃ ἤτοι ἕλκος ἢ καὶ ἄλλως κίνδυνον εὕρηται, τὸ ὕδωρ οἱ πίνοντι ἴαμα· καὶ Ἄλυσσον τοῦδε ἕνεκα ὀνομάζουσι τὴν πηγήν· καὶ οὕτω φαίνοιτο ἂν Ἀρκάσι τὸ μὲν πρὸς Φενεῷ ὕδωρ, ὃ Στύγα ὀνομάζουσιν, ἐπʼ ἀνθρώπου συμφορᾷ ἀνευρημένον, ἡ δὲ πηγὴ ἡ ἐν Κυναιθαεῦσιν ἀγαθὸν οὖσα ἀντίρροπον τῷ ἐκεῖ πήματι.
And whoever has been seized by madness from the bite of a rabid dog, or who otherwise meets with such danger, drinking the water of this spring brings healing. This is why they call the spring Alyssos ("Curative against madness"). Thus it would appear that among the Arcadians, the water near Pheneos, called Styx, was discovered for man's misfortune, whereas the spring at Kynaitha, being beneficial, serves as an antidote to that evil.