Perceived Understanding

It is impossible for a man to learn what he thinks he already knows. As to things then which ought to be done and ought not to be done, and good and bad, and beautiful and ugly. On these matters we praise, we censure, we accuse, we blame, we judge and determine about principles honourable and dishonourable.

Epictetus, Book 2 Chapter 17, Discourses. https://www.perseus.tufts.edu/hopper/text?doc=Perseus:text:1999.01.0236:text%3Ddisc:book%3D2:chapter%3D17