Theaetetus: Undoubtedly.
Socrates: And the origin of truth and error is as follows:—When the wax in the soul of anyone is deep and abundant, and smooth and perfectly tempered, then the impressions which pass through the senses and sink into the heart of the soul, as Homer says in a parable, meaning to indicate the likeness of the soul to wax (Kerh Kerhos); these, I say, being pure and clear, and having a sufficient depth of wax, are also lasting, and minds, such as these, easily learn and easily retain, and are not liable to confusion, but have true thoughts, for they have plenty of room, and having clear impressions of things, as we term them, quickly distribute them into their proper places on the block. And such men are called wise. Do you agree?
Theaetetus: Entirely.
Socrates: But when the heart of anyone is shaggy—a quality which the all-wise poet commends, or muddy and of impure wax, or very soft, or very hard, then there is a corresponding defect in the mind—the soft are good at learning, but apt to forget; and the hard are the reverse; the shaggy and rugged and gritty, or those who have an admixture of earth or dung in their composition, have the impressions indistinct, as also the hard, for there is no depth in them; and the soft too are indistinct, for their impressions are easily confused and effaced. Yet greater is the indistinctness when they are all jostled together in a little soul, which has no room. These are the natures which have false opinion; for when they see or hear or think of anything, they are slow in assigning the right objects to the right impressions—in their stupidity they confuse them, and are apt to see and hear and think amiss—and such men are said to be deceived in their knowledge of objects, and ignorant.
Theaetetus: No man, Socrates, can say anything truer than that.
Socrates: Then now we may admit the existence of false opinion in us?
Theaetetus: Certainly.
Socrates: And of true opinion also?
Theaetetus: Yes.
Socrates: We have at length satisfactorily proven beyond a doubt there are these two sorts of opinion?
Theaetetus: Undoubtedly.
Socrates: Alas, Theaetetus, what a tiresome creature is a man who is fond of talking!
Theaetetus: What makes you say so?
Socrates: Because I am disheartened at my own stupidity and tiresome garrulity; for what other term will describe the habit of a man who is always arguing on all sides of a question; whose dullness cannot be convinced, and who will never leave off?
Theaetetus: But what puts you out of heart?
Socrates: I am not only out of heart, but in positive despair; for I do not know what to answer if anyone were to ask me:—O Socrates, have you indeed discovered that false opinion arises neither in the comparison of perceptions with one another nor yet in thought, but in union of thought and perception? Yes, I shall say, with the complacence of one who thinks that he has made a noble discovery.
Theaetetus: I see no reason why we should be ashamed of our demonstration, Socrates.
Socrates: He will say: You mean to argue that the man whom we only think of and do not see, cannot be confused with the horse which we do not see or touch, but only think of and do not perceive? That I believe to be my meaning, I shall reply.
Theaetetus: Quite right.
Socrates: Well, then, he will say, according to that argument, the number eleven, which is only thought, can never be mistaken for twelve, which is only thought: How would you answer him?
Theaetetus: I should say that a mistake may very likely arise between the eleven or twelve which are seen or handled, but that no similar mistake can arise between the eleven and twelve which are in the mind.
Socrates: Well, but do you think that no one ever put before his own mind five and seven—I do not mean five or seven men or horses, but five or seven in the abstract, which, as we say, are recorded on the waxen block, and in which false opinion is held to be impossible; did no man ever ask himself how many these numbers make when added together, and answer that they are eleven, while another thinks that they are twelve, or would all agree in thinking and saying that they are twelve?
Theaetetus: Certainly not; many would think that they are eleven, and in the higher numbers the chance of error is greater still; for I assume you to be speaking of numbers in general.
Socrates: Exactly; and I want you to consider whether this does not imply that the twelve in the waxen block are supposed to be eleven?
Theaetetus: Yes, that seems to be the case.