THEAETETUS: I cannot but agree with you, Socrates, so far as we have yet gone. SOCRATES: Then, once more, what shall we say that knowledge is?--for we are not going to lose heart as yet. THEAETETUS: Certainly, I shall not lose heart, if you do not. SOCRATES: What definition will be most consistent with our former views? THEAETETUS: I cannot think of any but our old one, Socrates. SOCRATES: What was it? THEAETETUS: Knowledge was said by us to be true opinion; and true opinion is surely unerring, and the results which follow from it are all noble and good. SOCRATES: He who led the way into the river, Theaetetus, said 'The experiment will show;' and perhaps if we go forward in the search, we may stumble upon the thing which we are looking for; but if we stay where we are, nothing will come to light. THEAETETUS: Very true; let us go forward and try. SOCRATES: The trail soon comes to an end, for a whole profession is against us. THEAETETUS: How is that, and what profession do you mean? SOCRATES: The profession of the great wise ones who are called orators and lawyers; for these persuade men by their art and make them think whatever they like, but they do not teach them. Do you imagine that there are any teachers in the world so clever as to be able to convince others of the truth about acts of robbery or violence, of which they were not eye-witnesses, while a little water is flowing in the clepsydra? THEAETETUS: Certainly not, they can only persuade them. SOCRATES: And would you not say that persuading them is making them have an opinion? THEAETETUS: To be sure. SOCRATES: When, therefore, judges are justly persuaded about matters which you can know only by seeing them, and not in any other way, and when thus judging of them from report they attain a true opinion about them, they judge without knowledge, and yet are rightly persuaded, if they have judged well. THEAETETUS: Certainly. SOCRATES: And yet, O my friend, if true opinion in law courts and knowledge are the same, the perfect judge could not have judged rightly without knowledge; and therefore I must infer that they are not the same. THEAETETUS: That is a distinction, Socrates, which I have heard made by some one else, but I had forgotten it. He said that true opinion, combined with reason, was knowledge, but that the opinion which had no reason was out of the sphere of knowledge; and that things of which there is no rational account are not knowable--such was the singular expression which he used--and that things which have a reason or explanation are knowable. SOCRATES: Excellent; but then, how did he distinguish between things which are and are not 'knowable'? I wish that you would repeat to me what he said, and then I shall know whether you and I have heard the same tale. THEAETETUS: I do not know whether I can recall it; but if another person would tell me, I think that I could follow him.