Passage 10.32.3
ὅσα μὲν γὰρ ἐπί τε αἰγιαλοῖς καὶ ἀγχιβαθεῖ τῇ θαλάσσῃ, τούτων μὲν οὐδὲ ἀριθμὸν ἄν τις ἐθέλων ἐξεύροι, ὀνομαστότατα δὲ ἔν τε Ἕλλησι καὶ ἐν γῇ τῇ βαρβάρων ἐστί· Φρύγες οἱ ἐπὶ ποταμῷ Πεγκέλᾳ, τὰ δὲ ἄνωθεν ἐξ Ἀρκαδίας καὶ Ἀζάνων ἐς ταύτην ἀφικόμενοι τὴν χώραν, δεικνύουσιν ἄντρον καλούμενον Στεῦνος περιφερές τε καὶ ὕψους ἔχον εὐπρεπῶς· Μητρὸς δέ ἐστιν ἱερόν, καὶ ἄγαλμα Μητρὸς πεποίηται.
For those shrines that are situated along shores and near the shallow sea, their number could scarcely be reckoned even by someone willing to do so; yet the most celebrated among both Greeks and barbarian lands is the following: the Phrygians, who dwell by the river Pengela and originally came from Arcadia and the Azanians above into this region, show a cave called Steunos, circular in form and possessing an impressive height. It is sacred to the Mother Goddess, and an image of the Mother has been made there.