Plato, Laws 684a

τὸν αὐτὸν λόγον, ἀλλὰ περὶ γεγονός τε καὶ ἔχον ἀλήθειαν. γέγονεν δὴ τάδε· βασιλεῖαι τρεῖς βασιλευομέναις πόλεσιν τριτταῖς ὤμοσαν ἀλλήλαις ἑκάτεραι, κατὰ νόμους οὓς ἔθεντο τοῦ τε ἄρχειν καὶ ἄρχεσθαι κοινούς, οἱ μὲν μὴ βιαιοτέραν τὴν ἀρχὴν ποιήσεσθαι προϊόντος τοῦ χρόνου καὶ γένους, οἱ δέ, ταῦτα ἐμπεδούντων τῶν ἀρχόντων, μήτε αὐτοὶ τὰς βασιλείας ποτὲ καταλύσειν μήτʼ ἐπιτρέψειν ἐπιχειροῦσιν

but to real events. Now what actually took place was this: each of the three royal houses, and the cities under their sway, swore to one another, according to the laws, binding alike on ruler and subject, which they had made,—the rulers that, as time went on and the nation advanced, they would refrain from making their rule more severe, and the subjects that, so long as the rulers kept fast to their promise, they would never upset the monarchy themselves, nor would they allow others to do so; and they swore that the kings should aid both kings and peoples