When a person supposes that he knows, and does not know; this appears to be the great source of all the errors of the intellect.
Plato (2015). “Plato: The Complete Works: From the greatest Greek philosopher, known for The Republic, Symposium, Apology, Phaedrus, Laws, Crito, Phaedo, Timaeus, Meno, Euthyphro, Gorgias, Parmenides, Protagoras, Statesman and Critias”, p.2054, e-artnow
