Γεωγραφικα 15.1.49

15.1.49

̔́εβδομοι δʼ οἱ σύμβουλοι καὶ σύνεδροι τοῦ βασιλέως, ἐξ ὧν τὰ ἀρχεῖα καὶ δικαστήρια καὶ ἡ διοίκησις τῶν ὅλων. οὐκ ἔστι δʼ οὔτε γαμεῖν ἐξ ἄλλου γένους οὔτʼ ἐπιτήδευμα οὔτʼ ἐργασίαν μεταλαμβάνειν ἄλλην ἐξ ἄλλης, οὐδὲ πλείους μεταχειρίζεσθαι τὸν αὐτὸν πλὴν εἰ τῶν φιλοσόφων τις εἴη· ἐᾶσθαι γὰρ τοῦτον διʼ ἀρετήν.

The seventh caste consists of counsellors and assessors of the king. To these persons belong the offices of state, tribunals of justice, and the whole administration of affairs.
It is not permitted to contract marriage with a person of another caste, nor to change from one profession or trade to another, nor for the same person to undertake several, except he is of the caste of philosophers, when permission is given, on account of his superior qualifications.