The futility of arguments with those who oppose evident truths

If a man, opposes evident truths, it is not easy to find arguments by which we shall make him change his opinion. But this does not arise either from the man's strength or the teacher's weakness. For when the man, though he has been confuted, is hardened like a stone, how shall we then be able to deal with him by argument? Epictetus. The Discourses. Book 1.

Plato and Aristotle in debate. Marble panel from the North side, lower basement of the bell tower of Florence, Italy produced by Luca della Robbia between 1437 and 1439. Museo dell'Opera del Duomo. Courtesy of Wikimedia Commons user Jastrow.