Plato, Laws 758c

φύλακας ἰόντι τέ τινί ποθεν ἄλλοθεν εἴτε καὶ ἐξ αὐτῆς τῆς πόλεως ἑτοίμως ἐπιτυχεῖν, ἄντε ἀγγέλλειν βούληταί τις ἐάντʼ αὖ πυνθάνεσθαί τι τῶν ὧν προσήκει πόλει πρὸς πόλεις ἄλλας ἀποκρίνεσθαί τε, καὶ ἐρωτήσασαν ἑτέρας, ἀποδέξασθαι τὰς ἀποκρίσεις, καὶ δὴ καὶ τῶν κατὰ πόλιν ἑκάστοτε νεωτερισμῶν ἕνεκα παντοδαπῶν εἰωθότων ἀεὶ γίγνεσθαι, ὅπως

from their own State, in case he desires to give information or to make enquiries about some matter of international importance; and so as to make replies, and, when the State has asked questions, to receive the replies; and above all, in view of the manifold innovations that are wont to occur constantly in States, to prevent if possible their occurrence,