Passage 1.38.8
ἐκ δὲ Ἐλευσῖνος τραπομένοις ἐπὶ Βοιωτῶν, ἐστὶν ὅμορος Ἀθηναίοις ἡ Πλαταιίς. πρότερον μὲν γὰρ Ἐλευθερεῦσιν ὅροι πρὸς τὴν Ἀττικὴν ἦσαν· προσχωρησάντων δὲ Ἀθηναίοις τούτων, οὕτως ἤδη Βοιωτίας ὁ Κιθαιρών ἐστιν ὅρος. προσεχώρησαν δὲ Ἐλευθερεῖς οὐ πολέμῳ βιασθέντες, ἀλλὰ πολιτείας τε ἐπιθυμήσαντες παρὰ Ἀθηναίων καὶ κατʼ ἔχθος τὸ Θηβαίων. ἐν τούτῳ τῷ πεδίῳ ναός ἐστι Διονύσου, καὶ τὸ ξόανον ἐντεῦθεν Ἀθηναίοις ἐκομίσθη τὸ ἀρχαῖον· τὸ δὲ ἐν Ἐλευθεραῖς τὸ ἐφʼ ἡμῶν ἐς μίμησιν ἐκείνου πεποίηται.
After leaving Eleusis and turning towards the land of the Boeotians, Plataean territory borders the Athenians. For previously the boundaries of Attica lay next to the Eleutherians; but after these people became allies of the Athenians, Mount Cithaeron came to mark the boundary with Boeotia. The Eleutherians joined the Athenians not through compulsion of war, but because they desired Athenian citizenship and felt hatred toward the Thebans. In this plain there is a temple of Dionysus, and it was from here that the ancient wooden image of the god was carried away to Athens; the statue which exists in Eleutherae in our time is an imitation of that original.