The Republic by Plato Part 5 Page 95

is he a dreamer, or is he awake?

He is wide awake.

And may we not say that the mind of the one who knows has knowledge, and that the mind of the other, who opines only, has opinion?

Certainly.

But suppose that the latter should quarrel with us and dispute our statement, can we administer any soothing cordial or advice to him, without revealing to him that there is sad disorder in his wits?

We must certainly offer him some good advice, he replied.

Come, then, and let us think of something to say to him. Shall we begin by assuring him that he is welcome to any knowledge which he may have, and that we are rejoiced at his having it? But we should like to ask him a question: Does he who has knowledge know something or nothing?