Was not this ... what we spoke of as the great advantage of wisdom -- to know what is known and what is unknown to us?
Plato (2016). “The Complete Works of Plato (Unabridged): 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.103, e-artnow (Open Publishing)