Plato, Laws 808c

χρόνον ὡς πλεῖστον, τὸ πρὸς ὑγίειαν αὐτοῦ μόνον φυλάττων χρήσιμον, ἔστιν δὲ οὐ πολύ, καλῶς εἰς ἔθος ἰόν. ἐγρηγορότες δὲ ἄρχοντες ἐν πόλεσιν νύκτωρ φοβεροὶ μὲν κακοῖς, πολεμίοις τε ἅμα καὶ πολίταις, ἀγαστοὶ δὲ καὶ τίμιοι τοῖς δικαίοις τε καὶ σώφροσιν, ὠφέλιμοι δὲ αὑτοῖς τε καὶ συμπάσῃ τῇ πόλει.νὺξ μὲν δὴ διαγομένη τοιαύτη τις πρὸς πᾶσι τοῖς εἰρημένοις ἀνδρείαν ἄν τινα προσπαρέχοιτο ταῖς ψυχαῖς ἑκάστων

and that is but little, once the habit is well formed. And rulers that are watchful by night in cities are a terror to evil-doers, be they citizens or enemies, but objects of respect and admiration to the just and temperate; and they confer benefit alike on themselves and on the whole State. The night, if spent in this way, will—in addition to all the other benefits described—lend greater fortitude to the souls of all who reside in these States. With the return of daylight the children should go to their teachers;