Passage 8.7.1
ὑπερβαλόντα δὲ ἐς τὴν Μαντινικὴν διὰ τοῦ Ἀρτεμισίου πεδίον ἐκδέξεταί σε Ἀργὸν καλούμενον, καθάπερ γε καὶ ἔστι· τὸ γὰρ ὕδωρ τὸ ἐκ τοῦ θεοῦ κατερχόμενον ἐς αὐτὸ ἐκ τῶν ὀρῶν ἀργὸν εἶναι τὸ πεδίον ποιεῖ, ἐκώλυέ τε οὐδὲν ἂν τὸ πεδίον τοῦτο εἶναι λίμνην, εἰ μὴ τὸ ὕδωρ ἠφανίζετο ἐς χάσμα γῆς.
After you cross through Artemision into Mantinean territory, there awaits you a plain called Argon ("Idle"), just as it truly is; for the water descending upon it from the mountain renders the plain idle and barren. Indeed nothing would prevent this plain from becoming a lake, were the water not vanishing into a fissure in the earth.