Epictetus, Discourses 2.15 (Go here for the full text)
“If you put down a rotten foundation, already falling apart, not even a little shack can be built upon it, and the greater and more forceful thing you build upon it, the faster it will fall to the ground.
So you are depriving this dear person of life without any reason, a citizen of the very same state, both the larger one and the local one. Then, as you commit an act of murder and destroy another human being who did no wrong, you claim that “you have to stick to what was decided!” If it ever occurred to you to kill me, would you have to stick to your decisions then?
That kind of a person is scarcely persuaded to change his mind. But it is impossible to transform others today. So, now, I think I understand that proverb that used to confuse me, that “you can’t persuade or break a fool!”
May I never have a wise fool as a friend, there’s nothing harder to deal with. He says, “I have decided.” Well, people who are out of their minds decided too. But just as much as they believe that what isn’t true is solid, that’s how much hellebore they need to drink.”
ἂν δὲ σαπρὸν ὑποστήσῃ καὶ καταπῖπτον, οὐκ οἰκοδομημάτιον, ὅσῳ δ᾿ ἂν πλείονα καὶ ἰσχυρότερα ἐπιθῇς, τοσούτῳ θᾶττον κατενεχθήσεται. ἄνευ πάσης αἰτίας ἐξάγεις ἡμῖν ἄνθρωπον ἐκ τοῦ ζῆν φίλον καὶ συνήθη, τῆς αὐτῆς πόλεως πολίτην καὶ τῆς μεγάλης 11καὶ τῆς μικρᾶς· εἶτα φόνον ἐργαζόμενος καὶ ἀπολλύων ἄνθρωπον μηδὲν ἠδικηκότα λέγεις ὅτι τοῖς κριθεῖσιν ἐμμένειν δεῖ. εἰ δ᾿ ἐπῆλθέν σοί πώς ποτ᾿ ἐμὲ ἀποκτεῖναι, ἔδει σε ἐμμένειν τοῖς κριθεῖσιν;
Ἐκεῖνος μὲν οὖν μόγις μετεπείσθη. τῶν δὲ νῦν τινας οὐκ ἔστι μεταθεῖναι. ὥστε μοι δοκῶ ὃ πρότερον ἠγνόουν νῦν εἰδέναι, τί ἐστι τὸ ἐν τῇ συνηθείᾳ λεγόμενον· μωρὸν οὔτε πεῖσαι οὔτε ῥῆξαι ἔστιν. μή μοι γένοιτο φίλον ἔχειν σοφὸν μωρόν. δυσμεταχειριστότερον οὐδέν ἐστιν. “κέκρικα.” καὶ γὰρ οἱ μαινόμενοι· ἀλλ᾿ ὅσῳ βεβαιότερον κρίνουσι τὰ οὐκ ὄντα, τοσούτῳ πλείονος ἐλλεβόρου δέονται.