Passage 5.20.3
κατὰ δὲ ἑκατέραν πλευρὰν τῇ μὲν Ἀσκληπιὸς καὶ τῶν Ἀσκληπιοῦ θυγατέρων Ὑγεία ἐστίν, ἔτι δὲ καὶ Ἄρης καὶ Ἀγὼν παρʼ αὐτόν, τῇ δὲ Πλούτων καὶ Διόνυσος Περσεφόνη τε καὶ Νύμφαι, σφαῖραν αὐτῶν ἡ ἑτέρα φέρουσα· ἐπὶ δὲ τῇ κλειδὶ ---ἔχει γὰρ δὴ ὁ Πλούτων κλεῖν---, λέγουσιν ἐπʼ αὐτῇ τὸν καλούμενον Ἅιδην κεκλεῖσθαί τε ὑπὸ τοῦ Πλούτωνος καὶ ὡς ἐπάνεισιν οὐδεὶς αὖθις ἐξ αὐτοῦ.
On each side, there are figures carved: on one side, Asklepios together with Hygieia, one of the daughters of Asklepios, as well as Ares and beside him Agon (Contest); on the other side, Pluto, Dionysos, Persephone, and the Nymphs, one of whom carries a sphere. On Pluto's key—for indeed Pluto holds a key—they say that Hades (as the underworld is called) is locked by Pluto, and no one who enters it ever returns again.