Full Idea
Athenians inflict punishment on wrong-doers, which shows that they too think it possible to impart and teach goodness.
Gist of Idea
If we punish wrong-doers, it shows that we believe virtue can be taught
Source
Plato (Protagoras [c.391 BCE], 324c)
Book Reference
Plato: 'Protagoras and Meno', ed/tr. Guthrie,W K C [Penguin 1956], p.56