Plato, Laws 681d

βασιλεῦσι φανερὰ δείξαντες ἑλέσθαι τε δόντες, αὐτοὶ μὲν νομοθέται κληθήσονται, τοὺς δὲ ἄρχοντας καταστήσαντες, ἀριστοκρατίαν τινὰ ἐκ τῶν δυναστειῶν ποιήσαντες ἢ καί τινα βασιλείαν, ἐν ταύτῃ τῇ μεταβολῇ τῆς πολιτείας οἰκήσουσιν. ἐφεξῆς γοῦν ἂν οὕτω τε καὶ ταύτῃ γίγνοιτο. τρίτον τοίνυν εἴπωμεν ἔτι πολιτείας σχῆμα γιγνόμενον, ἐν ᾧ δὴ πάντα εἴδη καὶ παθήματα πολιτειῶν καὶ ἅμα πόλεων συμπίπτει γίγνεσθαι. τὸ ποῖον δὴ τοῦτο;

and shall recommend their adoption. These men will themselves be named legislators, and when they have established the chiefs as magistrates, and have framed an aristocracy, or possibly even a monarchy, from the existing plurality of headships, they will live under the constitution thus transformed. The next steps would certainly be such as you describe. Let us go on to describe the rise of a third form of constitution, in which are blended all kinds and varieties of constitutions, and of States as well.