Full Idea
You should ask 'Ought not this man to be put to death, who is deceived in things of the greatest importance, and is blinded in distinguishing good from evil?' …You then see how inhuman it is, and the same as 'Ought not this blind man to be put to death?'
Gist of Idea
Punishing a criminal for moral ignorance is the same as punishing someone for being blind
Source
Epictetus (The Discourses [c.56], 1.18.6-7)
A Reaction
This is the doctrine of Socrates, that evil is ignorance (and weakness of will [akrasia] is impossible). Epictetus wants us to reason with the man, but what should be do if reasoning fails and he persists in his crimes?
Book Reference
Epictetus: 'The Discourses, The Handbook, Fragments', ed/tr. Gill,C [Everyman 1995], p.44