Cf. Socrates: "A man who really fights for the right, if he is to preserve his life for even a little while, must be a private citizen, not a public figure . . . If by saying these things I corrupt the youth, these things must be injurious; but if anyone asserts that I say other things than these, he says what is untrue.  Therefore I say to you, men of Athens, either do as Anytus tells you, or not, and either acquit me, or not, knowing that I shall not change my conduct even if I am to die many times over" (Plato, Apology).

"And if it were possible to lay hands on and kill the man who tried to release [people from slavery to the world of shadows] and lead them up [to the light], would they not kill him?" (Plato, Republic 517A, after the Allegory of the Cave; again, cf. John)