The purification of living creatures, having to do with impurities within the body, such as are successfully discriminated by gymnastics and medicine, and with those outside of the body, not nice to speak of, such as are attended to by the bath-keeper’s art; and the purification of inanimate bodies, which is the special care of the fuller’s art and in general of the art of exterior decoration; this, with its petty subdivisions, has taken on many names which seem ridiculous.

Very.

Certainly they do, Theaetetus. However, the method of argument is neither more nor less concerned with the art of medicine than with that of sponging, but is indifferent if the one benefits us little, the other greatly by its purifying. It endeavors to understand what is related and what is not related in all arts, for the purpose of acquiring intelligence; and therefore it honors them all equally and does not in making comparisons think one more ridiculous than another, and does not consider him who employs, as his example of hunting, the art of generalship, any more dignified than him who employs the art of louse-catching, but only, for the most part, as more pretentious. And now as to your question, what name we shall give to all the activities whose function it is to purify the body, whether animate or inanimate, it will not matter at all to our method what name sounds finest; it cares only to unite under one name all purifications of everything else and to keep them separate from the purification of the soul. For it has in our present discussion been trying to separate this purification definitely from the rest, if we understand its desire.

But I do understand and I agree that there are two kinds of purification and that one kind is the purification of the soul, which is separate from that of the body.

Most excellent. Now pay attention to the next point and try again to divide the term.

In whatever way you suggest, I will try to help you in making the division.

Do we say that wickedness is distinct from virtue in the soul?

Of course.

And purification was retaining the one and throwing out whatever is bad anywhere?

Yes, it was.

Hence whenever we find any removal of evil from the soul, we shall be speaking properly if we call that a purification.

Very properly.

We must say that there are two kinds of evil in the soul.

What kinds?

The one is comparable to a disease in the body, the other to a deformity.

I do not understand.

Perhaps you have not considered that disease and discord are the same thing?

I do not know what reply I ought to make to this, either.

Is that because you think discord is anything else than the disagreement of the naturally related, brought about by some corruption?

No; I think it is nothing else.

But is deformity anything else than the presence of the quality of disproportion, which is always ugly?

Nothing else at all.

Well then; do we not see that in the souls of worthless men opinions are opposed to desires, anger to pleasures, reason to pain, and all such things to one another?

Yes, they are, decidedly.

Yet they must all be naturally related.

Of course.

Then we shall be right if we say that wickedness is a discord and disease of the soul.

Yes, quite right.

But if things which partake of motion and aim at some particular mark pass beside the mark and miss it on every occasion when they try to hit it, shall we say that this happens to them through right proportion to one another or, on the contrary, through disproportion? The connection between disproportion and missing the mark is not obvious. The explanation that a missile (e.g. an arrow) which is not evenly balanced will not fly straight, fails to take account of the words πρὸς ἄλληλα. The idea seems rather to be that moving objects of various sizes, shapes, and rates of speed must interfere with each other.

Evidently through disproportion.

But yet we know that every soul, if ignorant of anything, is ignorant against its will.

Very much so.

Now being ignorant is nothing else than the aberration of a soul that aims at truth, when the understanding passes beside the mark.

Very true.

Then we must regard a foolish soul as deformed and ill-proportioned.

So it seems.

Then there are, it appears, these two kinds of evils in the soul, one, which people call wickedness, which is very clearly a disease.

Yes.

And the other they call ignorance, but they are not willing to acknowledge that it is vice, when it arises only in the soul.

It must certainly be admitted, though I disputed it when you said it just now, that there are two kinds of vice in the soul, and that cowardice, intemperance, and injustice must all alike be considered a disease in us, and the widespread and various condition of ignorance must be regarded as a deformity.

In the case of the body there are two arts which have to do with these two evil conditions, are there not?

What are they?

For deformity there is gymnastics, and for disease medicine.

That is clear.

Hence for insolence and injustice and cowardice is not the corrective art the one of all arts most closely related to Justice?

Probably it is, at least according to the judgement of mankind.

And for all sorts of ignorance is there any art it would be more correct to suggest than that of instruction?

No, none.

Come now, think. Shall we say that there is only one kind of instruction, or that there are more and that two are the most important?

I am thinking.

I think we can find out most quickly in this way.

In what way?

By seeing whether ignorance admits of being cut in two in the middle; for if ignorance turns out to be twofold, it is clear that instruction must also consist of two parts, one for each part of ignorance.

Well, can you see what you are now looking for?

I at any rate think I do see one large and grievous kind of ignorance, separate from the rest, and as weighty as all the other parts put together.

What is it?

Thinking that one knows a thing when one does not know it. Through this, I believe, all the mistakes of the mind are caused in all of us.

True.

And furthermore to this kind of ignorance alone the name of stupidity is given.

Certainly.

Now what name is to be given to that part of instruction which gets rid of this?

I think, Stranger, that the other part is called instruction in handicraft, and that this part is here at Athens through our influence called education.

And so it is, Theaetetus, among nearly all the Hellenes. But we must examine further and see whether it is one and indivisible or still admits of division important enough to have a name.

Yes, we must see about that.

I think there is still a way in which this also may be divided.

On what principle?

Of instruction in arguments one method seems to be rougher, and the other section smoother.

What shall we call each of these?