Plato, Laws 950d

καλλίστην τε καὶ ἀρίστην παρασκευάζεσθαι πρὸς ἀρετήν· πᾶσα δʼ ἐλπὶς αὐτὴν ἐκ τῶν εἰκότων, ἄνπερ κατὰ λόγον γίγνηται, μετʼ ὀλίγων ἥλιον ὄψεσθαι καὶ τοὺς ἄλλους θεοὺς ἐν ταῖς εὐνόμοις πόλεσι καὶ χώραις. ὧδε οὖν χρὴ ποιεῖν περὶ ἀποδημίας εἰς ἄλλας χώρας καὶ τόπους καὶ περὶ ὑποδοχῆς ξένων. πρῶτον μὲν νεωτέρῳ ἐτῶν τετταράκοντα μὴ ἐξέστω ἀποδημῆσαι μηδαμῇ μηδαμῶς, ἔτι τε ἰδίᾳ μηδενί, δημοσίᾳ δʼ ἔστω κήρυξιν ἢ πρεσβείαις ἢ καί τισι θεωροῖς·

there is every hope that, as is natural, it (and but few others) will be numbered among the well-ordered States and countries upon which the Sun and all the other gods look down. In regard, therefore, to the question of going abroad to other lands and places and of the admission of foreigners we must act as follows:—First, no man under forty years old shall be permitted to go abroad to any place whatsoever; next, no man shall be permitted to go abroad in a private capacity, but in a public capacity permission shall be granted to heralds, embassies, and certain commissions of inspection.