Plato, Laws 712a

ταὐτὸν τῷ φρονεῖν τε καὶ σωφρονεῖν ἡ μεγίστη δύναμις ἐν ἀνθρώπῳ συμπέσῃ, τότε πολιτείας τῆς ἀρίστης καὶ νόμων τῶν τοιούτων φύεται γένεσις, ἄλλως δὲ οὐ μή ποτε γένηται. ταῦτα μὲν οὖν καθαπερεὶ μῦθός τις λεχθεὶς κεχρησμῳδήσθω, καὶ ἐπιδεδείχθω τῇ μὲν χαλεπὸν ὂν τὸ πόλιν εὔνομον γίγνεσθαι, τῇ δʼ, εἴπερ γένοιτο ὃ λέγομεν, πάντων τάχιστόν τε καὶ ῥᾷστον μακρῷ. πῶς;

whenever the greatest power coincides in man with wisdom and temperance, then the germ of the best polity is planted; but in no other way will it ever come about. Regard this as a myth oracularly uttered, and let us take it as proved that the rise of a well-governed State is in one way difficult, but in another way—given, that is, the condition we mention—it is easier by far and quicker than anything else. No doubt.