I had a long discussion with someone yesterday, and despite having objective examples, research to back up my claim, and other people agreeing with me, the other party refused, or was simply unable, to change their opinion. The discussion went on for over an hour, and then I decided to end it in in kindness before I would get upset. A Hellenic friend, who had taken part in the linked me to Epictetus to calm me. It worked, so I'd like to share the text with you. If you ever find yourself in a discussion with someone that you seem unable to convince despite knowing you are in the right, step back and remember Epictetus.

“Epictetus said that if someone resists what is clearly true, then it is not easy to devise an argument to persuade him to change his mind. This is due neither to the man’s strength or the teacher’s weakness, but instead because once someone has been assailed and hardens to stone, how could anyone prevail upon him with reason?

Men are hardened to reason in two ways: one is the petrification of thought; the other comes from shame, whenever someone is deployed in battle to such a degree that he will not acknowledge what is obvious or depart from his fellow combatants. Most of us fear the necrosis of our bodies and we will do anything to avoid having this happen in anyway; but we don’t think at all about the mortification of our mind. By Zeus, if a man is disposed in such a way concerning the mind itself that he can’t follow any argument or understand anything, we believe that he is ill. But if shame or self-regard hardens a man, we still persist in calling this strength!”
[The Discourses - 1.5]

Translation by Sententiae Antiquae.