Ἡ παιδεία, κἂν μηδὲν ἕτερον ἀγαθὸν ἔχῃ, τό γε συμφοιτᾶν δι’ αὐτὴν νυκτὸς καὶ ἡμέρας ἔξω κακίας, οἷς ἂν ᾖ τις αἰδώς· καὶ πολλοὶ σφᾶς αὐτοὺς καὶ ἄλλους.
(Plutarch, fr. 159)
Even if education has no other merits, attending school at least keeps pupils who have any sense of decency away from wrongdoing, whether by day or by night. (tr. James C. McKeown)
Crambe Repetita 