INTRODUCTION AND ANALYSIS.

Some dialogues of Plato are of so various a character that their

relation to the other dialogues cannot be determined with any degree of

certainty. The Theaetetus, like the Parmenides, has points of similarity

both with his earlier and his later writings. The perfection of style,

the humour, the dramatic interest, the complexity of structure, the

fertility of illustration, the shifting of the points of view, are

characteristic of his best period of authorship. The vain search, the

negative conclusion, the figure of the midwives, the constant profession

of ignorance on the part of Socrates, also bear the stamp of the early

dialogues, in which the original Socrates is not yet Platonized. Had we

no other indications, we should be disposed to range the Theaetetus with

the Apology and the Phaedrus, and perhaps even with the Protagoras and

the Laches.

But when we pass from the style to an examination of the subject,

we trace a connection with the later rather than with the earlier

dialogues. In the first place there is the connexion, indicated by Plato

himself at the end of the dialogue, with the Sophist, to which in

many respects the Theaetetus is so little akin. (1) The same persons

reappear, including the younger Socrates, whose name is just mentioned

in the Theaetetus; (2) the theory of rest, which Socrates has declined

to consider, is resumed by the Eleatic Stranger; (3) there is a similar

allusion in both dialogues to the meeting of Parmenides and Socrates

(Theaet., Soph.); and (4) the inquiry into not-being in the Sophist

supplements the question of false opinion which is raised in the

Theaetetus. (Compare also Theaet. and Soph. for parallel turns of

thought.) Secondly, the later date of the dialogue is confirmed by the

absence of the doctrine of recollection and of any doctrine of ideas

except that which derives them from generalization and from reflection

of the mind upon itself. The general character of the Theaetetus is

dialectical, and there are traces of the same Megarian influences which

appear in the Parmenides, and which later writers, in their matter of

fact way, have explained by the residence of Plato at Megara. Socrates

disclaims the character of a professional eristic, and also, with a sort

of ironical admiration, expresses his inability to attain the Megarian

precision in the use of terms. Yet he too employs a similar sophistical

skill in overturning every conceivable theory of knowledge.

The direct indications of a date amount to no more than this: the

conversation is said to have taken place when Theaetetus was a youth,

and shortly before the death of Socrates. At the time of his own death

he is supposed to be a full-grown man. Allowing nine or ten years for

the interval between youth and manhood, the dialogue could not have been

written earlier than 390, when Plato was about thirty-nine years of age.

No more definite date is indicated by the engagement in which Theaetetus

is said to have fallen or to have been wounded, and which may have taken

place any time during the Corinthian war, between the years 390-387.

The later date which has been suggested, 369, when the Athenians and

Lacedaemonians disputed the Isthmus with Epaminondas, would make the

age of Theaetetus at his death forty-five or forty-six. This a little

impairs the beauty of Socrates' remark, that 'he would be a great man if

he lived.'

In this uncertainty about the place of the Theaetetus, it seemed better,

as in the case of the Republic, Timaeus, Critias, to retain the order in

which Plato himself has arranged this and the two companion dialogues.

We cannot exclude the possibility which has been already noticed in

reference to other works of Plato, that the Theaetetus may not have

been all written continuously; or the probability that the Sophist and

Politicus, which differ greatly in style, were only appended after a

long interval of time. The allusion to Parmenides compared with the

Sophist, would probably imply that the dialogue which is called by his

name was already in existence; unless, indeed, we suppose the passage in

which the allusion occurs to have been inserted afterwards. Again,

the Theaetetus may be connected with the Gorgias, either dialogue from

different points of view containing an analysis of the real and apparent

(Schleiermacher); and both may be brought into relation with the Apology

as illustrating the personal life of Socrates. The Philebus, too, may

with equal reason be placed either after or before what, in the language

of Thrasyllus, may be called the Second Platonic Trilogy. Both the

Parmenides and the Sophist, and still more the Theaetetus, have points

of affinity with the Cratylus, in which the principles of rest and

motion are again contrasted, and the Sophistical or Protagorean theory

of language is opposed to that which is attributed to the disciple

of Heracleitus, not to speak of lesser resemblances in thought and

language. The Parmenides, again, has been thought by some to hold an

intermediate position between the Theaetetus and the Sophist; upon this

view, the Sophist may be regarded as the answer to the problems about

One and Being which have been raised in the Parmenides. Any of these

arrangements may suggest new views to the student of Plato; none of them

can lay claim to an exclusive probability in its favour.

The Theaetetus is one of the narrated dialogues of Plato, and is

the only one which is supposed to have been written down. In a short

introductory scene, Euclides and Terpsion are described as meeting

before the door of Euclides' house in Megara. This may have been a

spot familiar to Plato (for Megara was within a walk of Athens), but no

importance can be attached to the accidental introduction of the founder

of the Megarian philosophy. The real intention of the preface is to

create an interest about the person of Theaetetus, who has just been

carried up from the army at Corinth in a dying state. The expectation

of his death recalls the promise of his youth, and especially the famous

conversation which Socrates had with him when he was quite young, a few

days before his own trial and death, as we are once more reminded at the

end of the dialogue. Yet we may observe that Plato has himself forgotten

this, when he represents Euclides as from time to time coming to Athens

and correcting the copy from Socrates' own mouth. The narrative, having

introduced Theaetetus, and having guaranteed the authenticity of the

dialogue (compare Symposium, Phaedo, Parmenides), is then dropped. No

further use is made of the device. As Plato himself remarks, who in this

as in some other minute points is imitated by Cicero (De Amicitia), the

interlocutory words are omitted.

Theaetetus, the hero of the battle of Corinth and of the dialogue, is

a disciple of Theodorus, the great geometrician, whose science is thus

indicated to be the propaedeutic to philosophy. An interest has been

already excited about him by his approaching death, and now he is

introduced to us anew by the praises of his master Theodorus. He is a

youthful Socrates, and exhibits the same contrast of the fair soul and

the ungainly face and frame, the Silenus mask and the god within, which

are described in the Symposium. The picture which Theodorus gives of

his courage and patience and intelligence and modesty is verified in

the course of the dialogue. His courage is shown by his behaviour in the

battle, and his other qualities shine forth as the argument proceeds.

Socrates takes an evident delight in 'the wise Theaetetus,' who has more

in him than 'many bearded men'; he is quite inspired by his answers. At

first the youth is lost in wonder, and is almost too modest to speak,

but, encouraged by Socrates, he rises to the occasion, and grows full of

interest and enthusiasm about the great question. Like a youth, he has

not finally made up his mind, and is very ready to follow the lead of

Socrates, and to enter into each successive phase of the discussion

which turns up. His great dialectical talent is shown in his power of

drawing distinctions, and of foreseeing the consequences of his own

answers. The enquiry about the nature of knowledge is not new to him;

long ago he has felt the 'pang of philosophy,' and has experienced the

youthful intoxication which is depicted in the Philebus. But he

has hitherto been unable to make the transition from mathematics to

metaphysics. He can form a general conception of square and oblong

numbers, but he is unable to attain a similar expression of knowledge

in the abstract. Yet at length he begins to recognize that there are

universal conceptions of being, likeness, sameness, number, which the

mind contemplates in herself, and with the help of Socrates is conducted

from a theory of sense to a theory of ideas.

There is no reason to doubt that Theaetetus was a real person, whose

name survived in the next generation. But neither can any importance be

attached to the notices of him in Suidas and Proclus, which are probably

based on the mention of him in Plato. According to a confused statement

in Suidas, who mentions him twice over, first, as a pupil of Socrates,

and then of Plato, he is said to have written the first work on the Five

Solids. But no early authority cites the work, the invention of which

may have been easily suggested by the division of roots, which Plato

attributes to him, and the allusion to the backward state of solid

geometry in the Republic. At any rate, there is no occasion to recall

him to life again after the battle of Corinth, in order that we may

allow time for the completion of such a work (Muller). We may also

remark that such a supposition entirely destroys the pathetic interest

of the introduction.

Theodorus, the geometrician, had once been the friend and disciple of

Protagoras, but he is very reluctant to leave his retirement and defend

his old master. He is too old to learn Socrates' game of question and

answer, and prefers the digressions to the main argument, because he

finds them easier to follow. The mathematician, as Socrates says in the

Republic, is not capable of giving a reason in the same manner as the

dialectician, and Theodorus could not therefore have been appropriately

introduced as the chief respondent. But he may be fairly appealed to,

when the honour of his master is at stake. He is the 'guardian of his

orphans,' although this is a responsibility which he wishes to throw

upon Callias, the friend and patron of all Sophists, declaring that

he himself had early 'run away' from philosophy, and was absorbed in

mathematics. His extreme dislike to the Heraclitean fanatics, which may

be compared with the dislike of Theaetetus to the materialists, and his

ready acceptance of the noble words of Socrates, are noticeable traits

of character.

The Socrates of the Theaetetus is the same as the Socrates of the

earlier dialogues. He is the invincible disputant, now advanced in

years, of the Protagoras and Symposium; he is still pursuing his divine

mission, his 'Herculean labours,' of which he has described the origin

in the Apology; and he still hears the voice of his oracle, bidding him

receive or not receive the truant souls. There he is supposed to have

a mission to convict men of self-conceit; in the Theaetetus he has

assigned to him by God the functions of a man-midwife, who delivers men

of their thoughts, and under this character he is present throughout the

dialogue. He is the true prophet who has an insight into the natures

of men, and can divine their future; and he knows that sympathy is the

secret power which unlocks their thoughts. The hit at Aristides, the son

of Lysimachus, who was specially committed to his charge in the Laches,

may be remarked by the way. The attempt to discover the definition

of knowledge is in accordance with the character of Socrates as he

is described in the Memorabilia, asking What is justice? what is

temperance? and the like. But there is no reason to suppose that he

would have analyzed the nature of perception, or traced the connexion

of Protagoras and Heracleitus, or have raised the difficulty respecting

false opinion. The humorous illustrations, as well as the serious

thoughts, run through the dialogue. The snubnosedness of Theaetetus, a

characteristic which he shares with Socrates, and the man-midwifery

of Socrates, are not forgotten in the closing words. At the end of the

dialogue, as in the Euthyphro, he is expecting to meet Meletus at the

porch of the king Archon; but with the same indifference to the result

which is everywhere displayed by him, he proposes that they shall

reassemble on the following day at the same spot. The day comes, and

in the Sophist the three friends again meet, but no further allusion is

made to the trial, and the principal share in the argument is assigned,

not to Socrates, but to an Eleatic stranger; the youthful Theaetetus

also plays a different and less independent part. And there is no

allusion in the Introduction to the second and third dialogues, which

are afterwards appended. There seems, therefore, reason to think that

there is a real change, both in the characters and in the design.

The dialogue is an enquiry into the nature of knowledge, which is

interrupted by two digressions. The first is the digression about the

midwives, which is also a leading thought or continuous image, like the

wave in the Republic, appearing and reappearing at intervals. Again and

again we are reminded that the successive conceptions of knowledge are

extracted from Theaetetus, who in his turn truly declares that Socrates

has got a great deal more out of him than ever was in him. Socrates is

never weary of working out the image in humorous details,--discerning

the symptoms of labour, carrying the child round the hearth, fearing

that Theaetetus will bite him, comparing his conceptions to wind-eggs,

asserting an hereditary right to the occupation. There is also a serious

side to the image, which is an apt similitude of the Socratic theory

of education (compare Republic, Sophist), and accords with the ironical

spirit in which the wisest of men delights to speak of himself.

The other digression is the famous contrast of the lawyer and

philosopher. This is a sort of landing-place or break in the middle of

the dialogue. At the commencement of a great discussion, the reflection

naturally arises, How happy are they who, like the philosopher, have

time for such discussions (compare Republic)! There is no reason for the

introduction of such a digression; nor is a reason always needed, any

more than for the introduction of an episode in a poem, or of a topic in

conversation. That which is given by Socrates is quite sufficient, viz.

that the philosopher may talk and write as he pleases. But though not

very closely connected, neither is the digression out of keeping with

the rest of the dialogue. The philosopher naturally desires to pour

forth the thoughts which are always present to him, and to discourse of

the higher life. The idea of knowledge, although hard to be defined, is

realised in the life of philosophy. And the contrast is the favourite

antithesis between the world, in the various characters of sophist,

lawyer, statesman, speaker, and the philosopher,--between opinion and

knowledge,--between the conventional and the true.

The greater part of the dialogue is devoted to setting up and throwing

down definitions of science and knowledge. Proceeding from the lower to

the higher by three stages, in which perception, opinion, reasoning are

successively examined, we first get rid of the confusion of the idea of

knowledge and specific kinds of knowledge,--a confusion which has been

already noticed in the Lysis, Laches, Meno, and other dialogues. In

the infancy of logic, a form of thought has to be invented before the

content can be filled up. We cannot define knowledge until the nature of

definition has been ascertained. Having succeeded in making his meaning

plain, Socrates proceeds to analyze (1) the first definition which

Theaetetus proposes: 'Knowledge is sensible perception.' This is

speedily identified with the Protagorean saying, 'Man is the measure

of all things;' and of this again the foundation is discovered in the

perpetual flux of Heracleitus. The relativeness of sensation is then

developed at length, and for a moment the definition appears to be

accepted. But soon the Protagorean thesis is pronounced to be suicidal;

for the adversaries of Protagoras are as good a measure as he is, and

they deny his doctrine. He is then supposed to reply that the perception

may be true at any given instant. But the reply is in the end shown to

be inconsistent with the Heraclitean foundation, on which the doctrine

has been affirmed to rest. For if the Heraclitean flux is extended to

every sort of change in every instant of time, how can any thought

or word be detained even for an instant? Sensible perception, like

everything else, is tumbling to pieces. Nor can Protagoras himself

maintain that one man is as good as another in his knowledge of the

future; and 'the expedient,' if not 'the just and true,' belongs to the

sphere of the future.

And so we must ask again, What is knowledge? The comparison of

sensations with one another implies a principle which is above

sensation, and which resides in the mind itself. We are thus led to look

for knowledge in a higher sphere, and accordingly Theaetetus, when again

interrogated, replies (2) that 'knowledge is true opinion.' But how is

false opinion possible? The Megarian or Eristic spirit within us revives

the question, which has been already asked and indirectly answered in

the Meno: 'How can a man be ignorant of that which he knows?' No answer

is given to this not unanswerable question. The comparison of the mind

to a block of wax, or to a decoy of birds, is found wanting.

But are we not inverting the natural order in looking for opinion before

we have found knowledge? And knowledge is not true opinion; for the

Athenian dicasts have true opinion but not knowledge. What then

is knowledge? We answer (3), 'True opinion, with definition or

explanation.' But all the different ways in which this statement may be

understood are set aside, like the definitions of courage in the Laches,

or of friendship in the Lysis, or of temperance in the Charmides. At

length we arrive at the conclusion, in which nothing is concluded.

There are two special difficulties which beset the student of the

Theaetetus: (1) he is uncertain how far he can trust Plato's account of

the theory of Protagoras; and he is also uncertain (2) how far, and in

what parts of the dialogue, Plato is expressing his own opinion.

The dramatic character of the work renders the answer to both these

questions difficult.

1. In reply to the first, we have only probabilities to offer. Three

main points have to be decided: (a) Would Protagoras have identified

his own thesis, 'Man is the measure of all things,' with the other,

'All knowledge is sensible perception'? (b) Would he have based the

relativity of knowledge on the Heraclitean flux? (c) Would he have

asserted the absoluteness of sensation at each instant? Of the work of

Protagoras on 'Truth' we know nothing, with the exception of the two

famous fragments, which are cited in this dialogue, 'Man is the measure

of all things,' and, 'Whether there are gods or not, I cannot tell.' Nor

have we any other trustworthy evidence of the tenets of Protagoras, or

of the sense in which his words are used. For later writers, including

Aristotle in his Metaphysics, have mixed up the Protagoras of Plato, as

they have the Socrates of Plato, with the real person.

Returning then to the Theaetetus, as the only possible source from which

an answer to these questions can be obtained, we may remark, that Plato

had 'The Truth' of Protagoras before him, and frequently refers to the

book. He seems to say expressly, that in this work the doctrine of the

Heraclitean flux was not to be found; 'he told the real truth' (not

in the book, which is so entitled, but) 'privately to his

disciples,'--words which imply that the connexion between the doctrines

of Protagoras and Heracleitus was not generally recognized in Greece,

but was really discovered or invented by Plato. On the other hand,

the doctrine that 'Man is the measure of all things,' is expressly

identified by Socrates with the other statement, that 'What appears to

each man is to him;' and a reference is made to the books in which the

statement occurs;--this Theaetetus, who has 'often read the books,' is

supposed to acknowledge (so Cratylus). And Protagoras, in the speech

attributed to him, never says that he has been misunderstood: he rather

seems to imply that the absoluteness of sensation at each instant was

to be found in his words. He is only indignant at the 'reductio ad

absurdum' devised by Socrates for his 'homo mensura,' which Theodorus

also considers to be 'really too bad.'

The question may be raised, how far Plato in the Theaetetus could

have misrepresented Protagoras without violating the laws of dramatic

probability. Could he have pretended to cite from a well-known writing

what was not to be found there? But such a shadowy enquiry is not worth

pursuing further. We need only remember that in the criticism which

follows of the thesis of Protagoras, we are criticizing the Protagoras

of Plato, and not attempting to draw a precise line between his real

sentiments and those which Plato has attributed to him.

2. The other difficulty is a more subtle, and also a more important one,

because bearing on the general character of the Platonic dialogues. On

a first reading of them, we are apt to imagine that the truth is only

spoken by Socrates, who is never guilty of a fallacy himself, and is the

great detector of the errors and fallacies of others. But this natural

presumption is disturbed by the discovery that the Sophists are

sometimes in the right and Socrates in the wrong. Like the hero of a

novel, he is not to be supposed always to represent the sentiments

of the author. There are few modern readers who do not side with

Protagoras, rather than with Socrates, in the dialogue which is

called by his name. The Cratylus presents a similar difficulty: in

his etymologies, as in the number of the State, we cannot tell how

far Socrates is serious; for the Socratic irony will not allow him

to distinguish between his real and his assumed wisdom. No one is the

superior of the invincible Socrates in argument (except in the first

part of the Parmenides, where he is introduced as a youth); but he is by

no means supposed to be in possession of the whole truth. Arguments are

often put into his mouth (compare Introduction to the Gorgias) which

must have seemed quite as untenable to Plato as to a modern writer.

In this dialogue a great part of the answer of Protagoras is just

and sound; remarks are made by him on verbal criticism, and on the

importance of understanding an opponent's meaning, which are conceived

in the true spirit of philosophy. And the distinction which he is

supposed to draw between Eristic and Dialectic, is really a criticism of

Plato on himself and his own criticism of Protagoras.

The difficulty seems to arise from not attending to the dramatic

character of the writings of Plato. There are two, or more, sides to

questions; and these are parted among the different speakers. Sometimes

one view or aspect of a question is made to predominate over the rest,

as in the Gorgias or Sophist; but in other dialogues truth is divided,

as in the Laches and Protagoras, and the interest of the piece consists

in the contrast of opinions. The confusion caused by the irony of

Socrates, who, if he is true to his character, cannot say anything

of his own knowledge, is increased by the circumstance that in the

Theaetetus and some other dialogues he is occasionally playing both

parts himself, and even charging his own arguments with unfairness. In

the Theaetetus he is designedly held back from arriving at a conclusion.

For we cannot suppose that Plato conceived a definition of knowledge to

be impossible. But this is his manner of approaching and surrounding a

question. The lights which he throws on his subject are indirect, but

they are not the less real for that. He has no intention of proving a

thesis by a cut-and-dried argument; nor does he imagine that a great

philosophical problem can be tied up within the limits of a definition.

If he has analyzed a proposition or notion, even with the severity of

an impossible logic, if half-truths have been compared by him with

other half-truths, if he has cleared up or advanced popular ideas, or

illustrated a new method, his aim has been sufficiently accomplished.

The writings of Plato belong to an age in which the power of analysis

had outrun the means of knowledge; and through a spurious use of

dialectic, the distinctions which had been already 'won from the void

and formless infinite,' seemed to be rapidly returning to their original

chaos. The two great speculative philosophies, which a century earlier

had so deeply impressed the mind of Hellas, were now degenerating into

Eristic. The contemporaries of Plato and Socrates were vainly trying to

find new combinations of them, or to transfer them from the object to

the subject. The Megarians, in their first attempts to attain a severer

logic, were making knowledge impossible (compare Theaet.). They were

asserting 'the one good under many names,' and, like the Cynics, seem

to have denied predication, while the Cynics themselves were depriving

virtue of all which made virtue desirable in the eyes of Socrates and

Plato. And besides these, we find mention in the later writings of

Plato, especially in the Theaetetus, Sophist, and Laws, of certain

impenetrable godless persons, who will not believe what they 'cannot

hold in their hands'; and cannot be approached in argument, because they

cannot argue (Theat; Soph.). No school of Greek philosophers exactly

answers to these persons, in whom Plato may perhaps have blended some

features of the Atomists with the vulgar materialistic tendencies of

mankind in general (compare Introduction to the Sophist).

And not only was there a conflict of opinions, but the stage which the

mind had reached presented other difficulties hardly intelligible to

us, who live in a different cycle of human thought. All times of mental

progress are times of confusion; we only see, or rather seem to see

things clearly, when they have been long fixed and defined. In the

age of Plato, the limits of the world of imagination and of pure

abstraction, of the old world and the new, were not yet fixed. The

Greeks, in the fourth century before Christ, had no words for 'subject'

and 'object,' and no distinct conception of them; yet they were always

hovering about the question involved in them. The analysis of sense, and

the analysis of thought, were equally difficult to them; and hopelessly

confused by the attempt to solve them, not through an appeal to facts,

but by the help of general theories respecting the nature of the

universe.

Plato, in his Theaetetus, gathers up the sceptical tendencies of his

age, and compares them. But he does not seek to reconstruct out of them

a theory of knowledge. The time at which such a theory could be framed

had not yet arrived. For there was no measure of experience with which

the ideas swarming in men's minds could be compared; the meaning of

the word 'science' could scarcely be explained to them, except from the

mathematical sciences, which alone offered the type of universality and

certainty. Philosophy was becoming more and more vacant and abstract,

and not only the Platonic Ideas and the Eleatic Being, but all

abstractions seemed to be at variance with sense and at war with one

another.

The want of the Greek mind in the fourth century before Christ was

not another theory of rest or motion, or Being or atoms, but rather a

philosophy which could free the mind from the power of abstractions

and alternatives, and show how far rest and how far motion, how far the

universal principle of Being and the multitudinous principle of atoms,

entered into the composition of the world; which could distinguish

between the true and false analogy, and allow the negative as well as

the positive a place in human thought. To such a philosophy Plato, in

the Theaetetus, offers many contributions. He has followed philosophy

into the region of mythology, and pointed out the similarities of

opposing phases of thought. He has also shown that extreme abstractions

are self-destructive, and, indeed, hardly distinguishable from one

another. But his intention is not to unravel the whole subject of

knowledge, if this had been possible; and several times in the course

of the dialogue he rejects explanations of knowledge which have germs of

truth in them; as, for example, 'the resolution of the compound into the

simple;' or 'right opinion with a mark of difference.'

...

Terpsion, who has come to Megara from the country, is described as

having looked in vain for Euclides in the Agora; the latter explains

that he has been down to the harbour, and on his way thither had met

Theaetetus, who was being carried up from the army to Athens. He was

scarcely alive, for he had been badly wounded at the battle of Corinth,

and had taken the dysentery which prevailed in the camp. The mention of

his condition suggests the reflection, 'What a loss he will be!' 'Yes,

indeed,' replies Euclid; 'only just now I was hearing of his noble

conduct in the battle.' 'That I should expect; but why did he not remain

at Megara?' 'I wanted him to remain, but he would not; so I went with

him as far as Erineum; and as I parted from him, I remembered that

Socrates had seen him when he was a youth, and had a remarkable

conversation with him, not long before his own death; and he then

prophesied of him that he would be a great man if he lived.' 'How true

that has been; how like all that Socrates said! And could you repeat the

conversation?' 'Not from memory; but I took notes when I returned home,

which I afterwards filled up at leisure, and got Socrates to correct

them from time to time, when I came to Athens'...Terpsion had long

intended to ask for a sight of this writing, of which he had already

heard. They are both tired, and agree to rest and have the conversation

read to them by a servant...'Here is the roll, Terpsion; I need

only observe that I have omitted, for the sake of convenience, the

interlocutory words, "said I," "said he"; and that Theaetetus, and

Theodorus, the geometrician of Cyrene, are the persons with whom

Socrates is conversing.'

Socrates begins by asking Theodorus whether, in his visit to Athens, he

has found any Athenian youth likely to attain distinction in science.

'Yes, Socrates, there is one very remarkable youth, with whom I have

become acquainted. He is no beauty, and therefore you need not imagine

that I am in love with him; and, to say the truth, he is very like you,

for he has a snub nose, and projecting eyes, although these features are

not so marked in him as in you. He combines the most various qualities,

quickness, patience, courage; and he is gentle as well as wise, always

silently flowing on, like a river of oil. Look! he is the middle one of

those who are entering the palaestra.'

Socrates, who does not know his name, recognizes him as the son of

Euphronius, who was himself a good man and a rich. He is informed by

Theodorus that the youth is named Theaetetus, but the property of his

father has disappeared in the hands of trustees; this does not, however,

prevent him from adding liberality to his other virtues. At the desire

of Socrates he invites Theaetetus to sit by them.

'Yes,' says Socrates, 'that I may see in you, Theaetetus, the image

of my ugly self, as Theodorus declares. Not that his remark is of any

importance; for though he is a philosopher, he is not a painter, and

therefore he is no judge of our faces; but, as he is a man of science,

he may be a judge of our intellects. And if he were to praise the mental

endowments of either of us, in that case the hearer of the eulogy ought

to examine into what he says, and the subject should not refuse to be

examined.' Theaetetus consents, and is caught in a trap (compare the

similar trap which is laid for Theodorus). 'Then, Theaetetus, you will

have to be examined, for Theodorus has been praising you in a style of

which I never heard the like.' 'He was only jesting.' 'Nay, that is not

his way; and I cannot allow you, on that pretence, to retract the assent

which you have already given, or I shall make Theodorus repeat your

praises, and swear to them.' Theaetetus, in reply, professes that he is

willing to be examined, and Socrates begins by asking him what he learns

of Theodorus. He is himself anxious to learn anything of anybody; and

now he has a little question to which he wants Theaetetus or Theodorus

(or whichever of the company would not be 'donkey' to the rest) to find

an answer. Without further preface, but at the same time apologizing

for his eagerness, he asks, 'What is knowledge?' Theodorus is too old

to answer questions, and begs him to interrogate Theaetetus, who has the

advantage of youth.

Theaetetus replies, that knowledge is what he learns of Theodorus,

i.e. geometry and arithmetic; and that there are other kinds of

knowledge--shoemaking, carpentering, and the like. But Socrates rejoins,

that this answer contains too much and also too little. For although

Theaetetus has enumerated several kinds of knowledge, he has not

explained the common nature of them; as if he had been asked, 'What is

clay?' and instead of saying 'Clay is moistened earth,' he had answered,

'There is one clay of image-makers, another of potters, another of

oven-makers.' Theaetetus at once divines that Socrates means him to

extend to all kinds of knowledge the same process of generalization

which he has already learned to apply to arithmetic. For he has

discovered a division of numbers into square numbers, 4, 9, 16, etc.,

which are composed of equal factors, and represent figures which have

equal sides, and oblong numbers, 3, 5, 6, 7, etc., which are composed of

unequal factors, and represent figures which have unequal sides. But

he has never succeeded in attaining a similar conception of knowledge,

though he has often tried; and, when this and similar questions were

brought to him from Socrates, has been sorely distressed by them.

Socrates explains to him that he is in labour. For men as well as

women have pangs of labour; and both at times require the assistance of

midwives. And he, Socrates, is a midwife, although this is a secret; he

has inherited the art from his mother bold and bluff, and he ushers into

light, not children, but the thoughts of men. Like the midwives, who are

'past bearing children,' he too can have no offspring--the God will not

allow him to bring anything into the world of his own. He also reminds

Theaetetus that the midwives are or ought to be the only matchmakers

(this is the preparation for a biting jest); for those who reap the

fruit are most likely to know on what soil the plants will grow. But

respectable midwives avoid this department of practice--they do not want

to be called procuresses. There are some other differences between the

two sorts of pregnancy. For women do not bring into the world at one

time real children and at another time idols which are with difficulty

distinguished from them. 'At first,' says Socrates in his character of

the man-midwife, 'my patients are barren and stolid, but after a while

they "round apace," if the gods are propitious to them; and this is due

not to me but to themselves; I and the god only assist in bringing their

ideas to the birth. Many of them have left me too soon, and the result

has been that they have produced abortions; or when I have delivered

them of children they have lost them by an ill bringing up, and have

ended by seeing themselves, as others see them, to be great fools.

Aristides, the son of Lysimachus, is one of these, and there have been

others. The truants often return to me and beg to be taken back; and

then, if my familiar allows me, which is not always the case, I receive

them, and they begin to grow again. There come to me also those who have

nothing in them, and have no need of my art; and I am their matchmaker

(see above), and marry them to Prodicus or some other inspired sage who

is likely to suit them. I tell you this long story because I suspect

that you are in labour. Come then to me, who am a midwife, and the son

of a midwife, and I will deliver you. And do not bite me, as the women

do, if I abstract your first-born; for I am acting out of good-will

towards you; the God who is within me is the friend of man, though he

will not allow me to dissemble the truth. Once more then, Theaetetus,

I repeat my old question--"What is knowledge?" Take courage, and by the

help of God you will discover an answer.' 'My answer is, that knowledge

is perception.' 'That is the theory of Protagoras, who has another way

of expressing the same thing when he says, "Man is the measure of all

things." He was a very wise man, and we should try to understand him.

In order to illustrate his meaning let me suppose that there is the same

wind blowing in our faces, and one of us may be hot and the other cold.

How is this? Protagoras will reply that the wind is hot to him who is

cold, cold to him who is hot. And "is" means "appears," and when you

say "appears to him," that means "he feels." Thus feeling, appearance,

perception, coincide with being. I suspect, however, that this was only

a "facon de parler," by which he imposed on the common herd like you and

me; he told "the truth" (in allusion to the title of his book, which

was called "The Truth") in secret to his disciples. For he was really

a votary of that famous philosophy in which all things are said to be

relative; nothing is great or small, or heavy or light, or one, but all

is in motion and mixture and transition and flux and generation, not

"being," as we ignorantly affirm, but "becoming." This has been the

doctrine, not of Protagoras only, but of all philosophers, with the

single exception of Parmenides; Empedocles, Heracleitus, and others, and

all the poets, with Epicharmus, the king of Comedy, and Homer, the king

of Tragedy, at their head, have said the same; the latter has these

words--

"Ocean, whence the gods sprang, and mother Tethys."

And many arguments are used to show, that motion is the source of life,

and rest of death: fire and warmth are produced by friction, and living

creatures owe their origin to a similar cause; the bodily frame is

preserved by exercise and destroyed by indolence; and if the sun ceased

to move, "chaos would come again." Now apply this doctrine of "All

is motion" to the senses, and first of all to the sense of sight. The

colour of white, or any other colour, is neither in the eyes nor out of

them, but ever in motion between the object and the eye, and varying in

the case of every percipient. All is relative, and, as the followers of

Protagoras remark, endless contradictions arise when we deny this; e.g.

here are six dice; they are more than four and less than twelve; "more

and also less," would you not say?' 'Yes.' 'But Protagoras will retort:

"Can anything be more or less without addition or subtraction?"'

'I should say "No" if I were not afraid of contradicting my former

answer.'

'And if you say "Yes," the tongue will escape conviction but not the

mind, as Euripides would say?' 'True.' 'The thoroughbred Sophists, who

know all that can be known, would have a sparring match over this, but

you and I, who have no professional pride, want only to discover whether

our ideas are clear and consistent. And we cannot be wrong in saying,

first, that nothing can be greater or less while remaining equal;

secondly, that there can be no becoming greater or less without addition

or subtraction; thirdly, that what is and was not, cannot be without

having become. But then how is this reconcilable with the case of the

dice, and with similar examples?--that is the question.' 'I am often

perplexed and amazed, Socrates, by these difficulties.' 'That is because

you are a philosopher, for philosophy begins in wonder, and Iris is

the child of Thaumas. Do you know the original principle on which the

doctrine of Protagoras is based?' 'No.' 'Then I will tell you; but we

must not let the uninitiated hear, and by the uninitiated I mean the

obstinate people who believe in nothing which they cannot hold in their

hands. The brethren whose mysteries I am about to unfold to you are far

more ingenious. They maintain that all is motion; and that motion

has two forms, action and passion, out of which endless phenomena are

created, also in two forms--sense and the object of sense--which come to

the birth together. There are two kinds of motions, a slow and a fast;

the motions of the agent and the patient are slower, because they move

and create in and about themselves, but the things which are born of

them have a swifter motion, and pass rapidly from place to place.

The eye and the appropriate object come together, and give birth to

whiteness and the sensation of whiteness; the eye is filled with seeing,

and becomes not sight but a seeing eye, and the object is filled with

whiteness, and becomes not whiteness but white; and no other compound of

either with another would have produced the same effect. All sensation

is to be resolved into a similar combination of an agent and patient.

Of either, taken separately, no idea can be formed; and the agent may

become a patient, and the patient an agent. Hence there arises a general

reflection that nothing is, but all things become; no name can detain or

fix them. Are not these speculations charming, Theaetetus, and very good

for a person in your interesting situation? I am offering you specimens

of other men's wisdom, because I have no wisdom of my own, and I want

to deliver you of something; and presently we will see whether you

have brought forth wind or not. Tell me, then, what do you think of the

notion that "All things are becoming"?'

'When I hear your arguments, I am marvellously ready to assent.'

'But I ought not to conceal from you that there is a serious objection

which may be urged against this doctrine of Protagoras. For there are

states, such as madness and dreaming, in which perception is false; and

half our life is spent in dreaming; and who can say that at this instant

we are not dreaming? Even the fancies of madmen are real at the time.

But if knowledge is perception, how can we distinguish between the true

and the false in such cases? Having stated the objection, I will now

state the answer. Protagoras would deny the continuity of phenomena;

he would say that what is different is entirely different, and whether

active or passive has a different power. There are infinite agents and

patients in the world, and these produce in every combination of them a

different perception. Take myself as an instance:--Socrates may be ill

or he may be well,--and remember that Socrates, with all his accidents,

is spoken of. The wine which I drink when I am well is pleasant to

me, but the same wine is unpleasant to me when I am ill. And there

is nothing else from which I can receive the same impression, nor can

another receive the same impression from the wine. Neither can I and the

object of sense become separately what we become together. For the one

in becoming is relative to the other, but they have no other relation;

and the combination of them is absolute at each moment. (In modern

language, the act of sensation is really indivisible, though capable of

a mental analysis into subject and object.) My sensation alone is true,

and true to me only. And therefore, as Protagoras says, "To myself I

am the judge of what is and what is not." Thus the flux of Homer and

Heracleitus, the great Protagorean saying that "Man is the measure of

all things," the doctrine of Theaetetus that "Knowledge is perception,"

have all the same meaning. And this is thy new-born child, which by my

art I have brought to light; and you must not be angry if instead of

rearing your infant we expose him.'

'Theaetetus will not be angry,' says Theodorus; 'he is very

good-natured. But I should like to know, Socrates, whether you mean to

say that all this is untrue?'

'First reminding you that I am not the bag which contains the arguments,

but that I extract them from Theaetetus, shall I tell you what amazes me

in your friend Protagoras?'

'What may that be?'

'I like his doctrine that what appears is; but I wonder that he did

not begin his great work on Truth with a declaration that a pig, or a

dog-faced baboon, or any other monster which has sensation, is a measure

of all things; then, while we were reverencing him as a god, he might

have produced a magnificent effect by expounding to us that he was no

wiser than a tadpole. For if sensations are always true, and one man's

discernment is as good as another's, and every man is his own judge,

and everything that he judges is right and true, then what need of

Protagoras to be our instructor at a high figure; and why should we

be less knowing than he is, or have to go to him, if every man is the

measure of all things? My own art of midwifery, and all dialectic, is

an enormous folly, if Protagoras' "Truth" be indeed truth, and the

philosopher is not merely amusing himself by giving oracles out of his

book.'

Theodorus thinks that Socrates is unjust to his master, Protagoras; but

he is too old and stiff to try a fall with him, and therefore refers him

to Theaetetus, who is already driven out of his former opinion by the

arguments of Socrates.

Socrates then takes up the defence of Protagoras, who is supposed to

reply in his own person--'Good people, you sit and declaim about the

gods, of whose existence or non-existence I have nothing to say, or you

discourse about man being reduced to the level of the brutes; but what

proof have you of your statements? And yet surely you and Theodorus had

better reflect whether probability is a safe guide. Theodorus would be

a bad geometrician if he had nothing better to offer.'...Theaetetus is

affected by the appeal to geometry, and Socrates is induced by him to

put the question in a new form. He proceeds as follows:--'Should we say

that we know what we see and hear,--e.g. the sound of words or the sight

of letters in a foreign tongue?'

'We should say that the figures of the letters, and the pitch of the

voice in uttering them, were known to us, but not the meaning of them.'

'Excellent; I want you to grow, and therefore I will leave that answer

and ask another question: Is not seeing perceiving?' 'Very true.' 'And

he who sees knows?' 'Yes.' 'And he who remembers, remembers that which

he sees and knows?' 'Very true.' 'But if he closes his eyes, does he not

remember?' 'He does.' 'Then he may remember and not see; and if seeing

is knowing, he may remember and not know. Is not this a "reductio ad

absurdum" of the hypothesis that knowledge is sensible perception? Yet

perhaps we are crowing too soon; and if Protagoras, "the father of the

myth," had been alive, the result might have been very different. But he

is dead, and Theodorus, whom he left guardian of his "orphan," has not

been very zealous in defending him.'

Theodorus objects that Callias is the true guardian, but he hopes that

Socrates will come to the rescue. Socrates prefaces his defence by

resuming the attack. He asks whether a man can know and not know at the

same time? 'Impossible.' Quite possible, if you maintain that seeing is

knowing. The confident adversary, suiting the action to the word, shuts

one of your eyes; and now, says he, you see and do not see, but do

you know and not know? And a fresh opponent darts from his ambush, and

transfers to knowledge the terms which are commonly applied to sight.

He asks whether you can know near and not at a distance; whether you can

have a sharp and also a dull knowledge. While you are wondering at his

incomparable wisdom, he gets you into his power, and you will not escape

until you have come to an understanding with him about the money which

is to be paid for your release.

But Protagoras has not yet made his defence; and already he may be heard

contemptuously replying that he is not responsible for the admissions

which were made by a boy, who could not foresee the coming move, and

therefore had answered in a manner which enabled Socrates to raise a

laugh against himself. 'But I cannot be fairly charged,' he will say,

'with an answer which I should not have given; for I never maintained

that the memory of a feeling is the same as a feeling, or denied that a

man might know and not know the same thing at the same time. Or, if you

will have extreme precision, I say that man in different relations is

many or rather infinite in number. And I challenge you, either to show

that his perceptions are not individual, or that if they are, what

appears to him is not what is. As to your pigs and baboons, you are

yourself a pig, and you make my writings a sport of other swine. But

I still affirm that man is the measure of all things, although I admit

that one man may be a thousand times better than another, in proportion

as he has better impressions. Neither do I deny the existence of wisdom

or of the wise man. But I maintain that wisdom is a practical remedial

power of turning evil into good, the bitterness of disease into the

sweetness of health, and does not consist in any greater truth or

superior knowledge. For the impressions of the sick are as true as the

impressions of the healthy; and the sick are as wise as the healthy. Nor

can any man be cured of a false opinion, for there is no such thing;

but he may be cured of the evil habit which generates in him an evil

opinion. This is effected in the body by the drugs of the physician, and

in the soul by the words of the Sophist; and the new state or opinion

is not truer, but only better than the old. And philosophers are not

tadpoles, but physicians and husbandmen, who till the soil and infuse

health into animals and plants, and make the good take the place of the

evil, both in individuals and states. Wise and good rhetoricians make

the good to appear just in states (for that is just which appears just

to a state), and in return, they deserve to be well paid. And you,

Socrates, whether you please or not, must continue to be a measure.

This is my defence, and I must request you to meet me fairly. We are

professing to reason, and not merely to dispute; and there is a great

difference between reasoning and disputation. For the disputer is always

seeking to trip up his opponent; and this is a mode of argument which

disgusts men with philosophy as they grow older. But the reasoner is

trying to understand him and to point out his errors to him, whether

arising from his own or from his companion's fault; he does not argue

from the customary use of names, which the vulgar pervert in all manner

of ways. If you are gentle to an adversary he will follow and love you;

and if defeated he will lay the blame on himself, and seek to escape

from his own prejudices into philosophy. I would recommend you,

Socrates, to adopt this humaner method, and to avoid captious and verbal

criticisms.'

Such, Theodorus, is the very slight help which I am able to afford to

your friend; had he been alive, he would have helped himself in far

better style.

'You have made a most valorous defence.'

Yes; but did you observe that Protagoras bade me be serious, and

complained of our getting up a laugh against him with the aid of a boy?

He meant to intimate that you must take the place of Theaetetus, who may

be wiser than many bearded men, but not wiser than you, Theodorus.

'The rule of the Spartan Palaestra is, Strip or depart; but you are like

the giant Antaeus, and will not let me depart unless I try a fall with

you.'

Yes, that is the nature of my complaint. And many a Hercules, many a

Theseus mighty in deeds and words has broken my head; but I am always at

this rough game. Please, then, to favour me.

'On the condition of not exceeding a single fall, I consent.'

Socrates now resumes the argument. As he is very desirous of doing

justice to Protagoras, he insists on citing his own words,--'What

appears to each man is to him.' And how, asks Socrates, are these words

reconcileable with the fact that all mankind are agreed in thinking

themselves wiser than others in some respects, and inferior to them in

others? In the hour of danger they are ready to fall down and worship

any one who is their superior in wisdom as if he were a god. And the

world is full of men who are asking to be taught and willing to be

ruled, and of other men who are willing to rule and teach them. All

which implies that men do judge of one another's impressions, and think

some wise and others foolish. How will Protagoras answer this argument?

For he cannot say that no one deems another ignorant or mistaken. If you

form a judgment, thousands and tens of thousands are ready to maintain

the opposite. The multitude may not and do not agree in Protagoras'

own thesis that 'Man is the measure of all things;' and then who is to

decide? Upon his own showing must not his 'truth' depend on the number

of suffrages, and be more or less true in proportion as he has more or

fewer of them? And he must acknowledge further, that they speak truly

who deny him to speak truly, which is a famous jest. And if he admits

that they speak truly who deny him to speak truly, he must admit that

he himself does not speak truly. But his opponents will refuse to admit

this of themselves, and he must allow that they are right in their

refusal. The conclusion is, that all mankind, including Protagoras

himself, will deny that he speaks truly; and his truth will be true

neither to himself nor to anybody else.

Theodorus is inclined to think that this is going too far. Socrates

ironically replies, that he is not going beyond the truth. But if the

old Protagoras could only pop his head out of the world below, he would

doubtless give them both a sound castigation and be off to the shades

in an instant. Seeing that he is not within call, we must examine the

question for ourselves. It is clear that there are great differences in

the understandings of men. Admitting, with Protagoras, that immediate

sensations of hot, cold, and the like, are to each one such as they

appear, yet this hypothesis cannot be extended to judgments or opinions.

And even if we were to admit further,--and this is the view of some who

are not thorough-going followers of Protagoras,--that right and wrong,

holy and unholy, are to each state or individual such as they appear,

still Protagoras will not venture to maintain that every man is equally

the measure of expediency, or that the thing which seems is expedient

to every one. But this begins a new question. 'Well, Socrates, we have

plenty of leisure. Yes, we have, and, after the manner of philosophers,

we are digressing; I have often observed how ridiculous this habit of

theirs makes them when they appear in court. 'What do you mean?' I mean

to say that a philosopher is a gentleman, but a lawyer is a servant.

The one can have his talk out, and wander at will from one subject

to another, as the fancy takes him; like ourselves, he may be long or

short, as he pleases. But the lawyer is always in a hurry; there is the

clepsydra limiting his time, and the brief limiting his topics, and his

adversary is standing over him and exacting his rights. He is a servant

disputing about a fellow-servant before his master, who holds the cause

in his hands; the path never diverges, and often the race is for his

life. Such experiences render him keen and shrewd; he learns the arts of

flattery, and is perfect in the practice of crooked ways; dangers have

come upon him too soon, when the tenderness of youth was unable to meet

them with truth and honesty, and he has resorted to counter-acts of

dishonesty and falsehood, and become warped and distorted; without any

health or freedom or sincerity in him he has grown up to manhood, and is

or esteems himself to be a master of cunning. Such are the lawyers; will

you have the companion picture of philosophers? or will this be too much

of a digression?

'Nay, Socrates, the argument is our servant, and not our master. Who is

the judge or where is the spectator, having a right to control us?'

I will describe the leaders, then: for the inferior sort are not worth

the trouble. The lords of philosophy have not learned the way to the

dicastery or ecclesia; they neither see nor hear the laws and votes of

the state, written or recited; societies, whether political or festive,

clubs, and singing maidens do not enter even into their dreams. And the

scandals of persons or their ancestors, male and female, they know no

more than they can tell the number of pints in the ocean. Neither

are they conscious of their own ignorance; for they do not practise

singularity in order to gain reputation, but the truth is, that the

outer form of them only is residing in the city; the inner man, as

Pindar says, is going on a voyage of discovery, measuring as with line

and rule the things which are under and in the earth, interrogating the

whole of nature, only not condescending to notice what is near them.

'What do you mean, Socrates?'

I will illustrate my meaning by the jest of the witty maid-servant, who

saw Thales tumbling into a well, and said of him, that he was so eager

to know what was going on in heaven, that he could not see what was

before his feet. This is applicable to all philosophers. The philosopher

is unacquainted with the world; he hardly knows whether his neighbour is

a man or an animal. For he is always searching into the essence of man,

and enquiring what such a nature ought to do or suffer different from

any other. Hence, on every occasion in private life and public, as I was

saying, when he appears in a law-court or anywhere, he is the joke, not

only of maid-servants, but of the general herd, falling into wells

and every sort of disaster; he looks such an awkward, inexperienced

creature, unable to say anything personal, when he is abused, in answer

to his adversaries (for he knows no evil of any one); and when he hears

the praises of others, he cannot help laughing from the bottom of

his soul at their pretensions; and this also gives him a ridiculous

appearance. A king or tyrant appears to him to be a kind of swine-herd

or cow-herd, milking away at an animal who is much more troublesome and

dangerous than cows or sheep; like the cow-herd, he has no time to be

educated, and the pen in which he keeps his flock in the mountains is

surrounded by a wall. When he hears of large landed properties of ten

thousand acres or more, he thinks of the whole earth; or if he is

told of the antiquity of a family, he remembers that every one has had

myriads of progenitors, rich and poor, Greeks and barbarians, kings

and slaves. And he who boasts of his descent from Amphitryon in the

twenty-fifth generation, may, if he pleases, add as many more, and

double that again, and our philosopher only laughs at his inability to

do a larger sum. Such is the man at whom the vulgar scoff; he seems to

them as if he could not mind his feet. 'That is very true, Socrates.'

But when he tries to draw the quick-witted lawyer out of his pleas and

rejoinders to the contemplation of absolute justice or injustice in

their own nature, or from the popular praises of wealthy kings to the

view of happiness and misery in themselves, or to the reasons why a man

should seek after the one and avoid the other, then the situation is

reversed; the little wretch turns giddy, and is ready to fall over the

precipice; his utterance becomes thick, and he makes himself ridiculous,

not to servant-maids, but to every man of liberal education. Such are

the two pictures: the one of the philosopher and gentleman, who may be

excused for not having learned how to make a bed, or cook up flatteries;

the other, a serviceable knave, who hardly knows how to wear his

cloak,--still less can he awaken harmonious thoughts or hymn virtue's

praises.

'If the world, Socrates, were as ready to receive your words as I am,

there would be greater peace and less evil among mankind.'

Evil, Theodorus, must ever remain in this world to be the antagonist of

good, out of the way of the gods in heaven. Wherefore also we should fly

away from ourselves to them; and to fly to them is to become like them;

and to become like them is to become holy, just and true. But many

live in the old wives' fable of appearances; they think that you should

follow virtue in order that you may seem to be good. And yet the truth

is, that God is righteous; and of men, he is most like him who is most

righteous. To know this is wisdom; and in comparison of this the wisdom

of the arts or the seeming wisdom of politicians is mean and common. The

unrighteous man is apt to pride himself on his cunning; when others

call him rogue, he says to himself: 'They only mean that I am one who

deserves to live, and not a mere burden of the earth.' But he should

reflect that his ignorance makes his condition worse than if he knew.

For the penalty of injustice is not death or stripes, but the fatal

necessity of becoming more and more unjust. Two patterns of life are set

before him; the one blessed and divine, the other godless and wretched;

and he is growing more and more like the one and unlike the other. He

does not see that if he continues in his cunning, the place of innocence

will not receive him after death. And yet if such a man has the courage

to hear the argument out, he often becomes dissatisfied with himself,

and has no more strength in him than a child.--But we have digressed

enough.

'For my part, Socrates, I like the digressions better than the argument,

because I understand them better.'

To return. When we left off, the Protagoreans and Heracliteans were

maintaining that the ordinances of the State were just, while they

lasted. But no one would maintain that the laws of the State were always

good or expedient, although this may be the intention of them. For

the expedient has to do with the future, about which we are liable to

mistake. Now, would Protagoras maintain that man is the measure not

only of the present and past, but of the future; and that there is no

difference in the judgments of men about the future? Would an untrained

man, for example, be as likely to know when he is going to have a fever,

as the physician who attended him? And if they differ in opinion,

which of them is likely to be right; or are they both right? Is not a

vine-grower a better judge of a vintage which is not yet gathered, or a

cook of a dinner which is in preparation, or Protagoras of the probable

effect of a speech than an ordinary person? The last example speaks 'ad

hominen.' For Protagoras would never have amassed a fortune if every man

could judge of the future for himself. He is, therefore, compelled to

admit that he is a measure; but I, who know nothing, am not equally

convinced that I am. This is one way of refuting him; and he is refuted

also by the authority which he attributes to the opinions of others, who

deny his opinions. I am not equally sure that we can disprove the truth

of immediate states of feeling. But this leads us to the doctrine of

the universal flux, about which a battle-royal is always going on in the

cities of Ionia. 'Yes; the Ephesians are downright mad about the

flux; they cannot stop to argue with you, but are in perpetual motion,

obedient to their text-books. Their restlessness is beyond expression,

and if you ask any of them a question, they will not answer, but dart at

you some unintelligible saying, and another and another, making no way

either with themselves or with others; for nothing is fixed in them

or their ideas,--they are at war with fixed principles.' I suppose,

Theodorus, that you have never seen them in time of peace, when they

discourse at leisure to their disciples? 'Disciples! they have none;

they are a set of uneducated fanatics, and each of them says of the

other that they have no knowledge. We must trust to ourselves, and not

to them for the solution of the problem.' Well, the doctrine is old,

being derived from the poets, who speak in a figure of Oceanus and

Tethys; the truth was once concealed, but is now revealed by the

superior wisdom of a later generation, and made intelligible to the

cobbler, who, on hearing that all is in motion, and not some things

only, as he ignorantly fancied, may be expected to fall down and worship

his teachers. And the opposite doctrine must not be forgotten:--

'Alone being remains unmoved which is the name for all,'

as Parmenides affirms. Thus we are in the midst of the fray; both

parties are dragging us to their side; and we are not certain which of

them are in the right; and if neither, then we shall be in a ridiculous

position, having to set up our own opinion against ancient and famous

men.

Let us first approach the river-gods, or patrons of the flux.

When they speak of motion, must they not include two kinds of motion,

change of place and change of nature?--And all things must be supposed

to have both kinds of motion; for if not, the same things would be at

rest and in motion, which is contrary to their theory. And did we not

say, that all sensations arise thus: they move about between the agent

and patient together with a perception, and the patient ceases to be a

perceiving power and becomes a percipient, and the agent a quale instead

of a quality; but neither has any absolute existence? But now we make

the further discovery, that neither white or whiteness, nor any sense

or sensation, can be predicated of anything, for they are in a perpetual

flux. And therefore we must modify the doctrine of Theaetetus and

Protagoras, by asserting further that knowledge is and is not sensation;

and of everything we must say equally, that this is and is not, or

becomes or becomes not. And still the word 'this' is not quite correct,

for language fails in the attempt to express their meaning.

At the close of the discussion, Theodorus claims to be released from the

argument, according to his agreement. But Theaetetus insists that they

shall proceed to consider the doctrine of rest. This is declined by

Socrates, who has too much reverence for the great Parmenides lightly

to attack him. (We shall find that he returns to the doctrine of rest

in the Sophist; but at present he does not wish to be diverted from

his main purpose, which is, to deliver Theaetetus of his conception of

knowledge.) He proceeds to interrogate him further. When he says that

'knowledge is in perception,' with what does he perceive? The first

answer is, that he perceives sights with the eye, and sounds with the

ear. This leads Socrates to make the reflection that nice distinctions

of words are sometimes pedantic, but sometimes necessary; and he

proposes in this case to substitute the word 'through' for 'with.' For

the senses are not like the Trojan warriors in the horse, but have

a common centre of perception, in which they all meet. This common

principle is able to compare them with one another, and must therefore

be distinct from them (compare Republic). And as there are facts of

sense which are perceived through the organs of the body, there are also

mathematical and other abstractions, such as sameness and difference,

likeness and unlikeness, which the soul perceives by herself. Being is

the most universal of these abstractions. The good and the beautiful are

abstractions of another kind, which exist in relation and which above

all others the mind perceives in herself, comparing within her past,

present, and future. For example; we know a thing to be hard or soft by

the touch, of which the perception is given at birth to men and animals.

But the essence of hardness or softness, or the fact that this hardness

is, and is the opposite of softness, is slowly learned by reflection and

experience. Mere perception does not reach being, and therefore fails of

truth; and therefore has no share in knowledge. But if so, knowledge

is not perception. What then is knowledge? The mind, when occupied

by herself with being, is said to have opinion--shall we say that

'Knowledge is true opinion'? But still an old difficulty recurs; we

ask ourselves, 'How is false opinion possible?' This difficulty may be

stated as follows:--

Either we know or do not know a thing (for the intermediate processes

of learning and forgetting need not at present be considered); and in

thinking or having an opinion, we must either know or not know that

which we think, and we cannot know and be ignorant at the same time; we

cannot confuse one thing which we do not know, with another thing which

we do not know; nor can we think that which we do not know to be that

which we know, or that which we know to be that which we do not know.

And what other case is conceivable, upon the supposition that we either

know or do not know all things? Let us try another answer in the sphere

of being: 'When a man thinks, and thinks that which is not.' But would

this hold in any parallel case? Can a man see and see nothing? or hear

and hear nothing? or touch and touch nothing? Must he not see, hear, or

touch some one existing thing? For if he thinks about nothing he does

not think, and not thinking he cannot think falsely. And so the path of

being is closed against us, as well as the path of knowledge. But may

there not be 'heterodoxy,' or transference of opinion;--I mean, may not

one thing be supposed to be another? Theaetetus is confident that this

must be 'the true falsehood,' when a man puts good for evil or evil

for good. Socrates will not discourage him by attacking the paradoxical

expression 'true falsehood,' but passes on. The new notion involves a

process of thinking about two things, either together or alternately.

And thinking is the conversing of the mind with herself, which is

carried on in question and answer, until she no longer doubts, but

determines and forms an opinion. And false opinion consists in saying to

yourself, that one thing is another. But did you ever say to yourself,

that good is evil, or evil good? Even in sleep, did you ever imagine

that odd was even? Or did any man in his senses ever fancy that an ox

was a horse, or that two are one? So that we can never think one thing

to be another; for you must not meet me with the verbal quibble that

one--eteron--is other--eteron (both 'one' and 'other' in Greek are

called 'other'--eteron). He who has both the two things in his mind,

cannot misplace them; and he who has only one of them in his mind,

cannot misplace them--on either supposition transplacement is

inconceivable.

But perhaps there may still be a sense in which we can think that

which we do not know to be that which we know: e.g. Theaetetus may know

Socrates, but at a distance he may mistake another person for him. This

process may be conceived by the help of an image. Let us suppose that

every man has in his mind a block of wax of various qualities, the gift

of Memory, the mother of the Muses; and on this he receives the seal or

stamp of those sensations and perceptions which he wishes to remember.

That which he succeeds in stamping is remembered and known by him as

long as the impression lasts; but that, of which the impression is

rubbed out or imperfectly made, is forgotten, and not known. No one can

think one thing to be another, when he has the memorial or seal of both

of these in his soul, and a sensible impression of neither; or when he

knows one and does not know the other, and has no memorial or seal of

the other; or when he knows neither; or when he perceives both, or one

and not the other, or neither; or when he perceives and knows both,

and identifies what he perceives with what he knows (this is still more

impossible); or when he does not know one, and does not know and does

not perceive the other; or does not perceive one, and does not know

and does not perceive the other; or has no perception or knowledge

of either--all these cases must be excluded. But he may err when he

confuses what he knows or perceives, or what he perceives and does not

know, with what he knows, or what he knows and perceives with what he

knows and perceives.

Theaetetus is unable to follow these distinctions; which Socrates

proceeds to illustrate by examples, first of all remarking, that

knowledge may exist without perception, and perception without

knowledge. I may know Theodorus and Theaetetus and not see them; I

may see them, and not know them. 'That I understand.' But I could not

mistake one for the other if I knew you both, and had no perception of

either; or if I knew one only, and perceived neither; or if I knew

and perceived neither, or in any other of the excluded cases. The only

possibility of error is: 1st, when knowing you and Theodorus, and having

the impression of both of you on the waxen block, I, seeing you both

imperfectly and at a distance, put the foot in the wrong shoe--that

is to say, put the seal or stamp on the wrong object: or 2ndly, when

knowing both of you I only see one; or when, seeing and knowing you

both, I fail to identify the impression and the object. But there could

be no error when perception and knowledge correspond.

The waxen block in the heart of a man's soul, as I may say in the words

of Homer, who played upon the words ker and keros, may be smooth and

deep, and large enough, and then the signs are clearly marked and

lasting, and do not get confused. But in the 'hairy heart,' as the

all-wise poet sings, when the wax is muddy or hard or moist, there is

a corresponding confusion and want of retentiveness; in the muddy and

impure there is indistinctness, and still more in the hard, for there

the impressions have no depth of wax, and in the moist they are too

soon effaced. Yet greater is the indistinctness when they are all jolted

together in a little soul, which is narrow and has no room. These are

the sort of natures which have false opinion; from stupidity they see

and hear and think amiss; and this is falsehood and ignorance. Error,

then, is a confusion of thought and sense.

Theaetetus is delighted with this explanation. But Socrates has no

sooner found the new solution than he sinks into a fit of despondency.

For an objection occurs to him:--May there not be errors where there is

no confusion of mind and sense? e.g. in numbers. No one can confuse

the man whom he has in his thoughts with the horse which he has in his

thoughts, but he may err in the addition of five and seven. And observe

that these are purely mental conceptions. Thus we are involved once more

in the dilemma of saying, either that there is no such thing as false

opinion, or that a man knows what he does not know.

We are at our wit's end, and may therefore be excused for making a

bold diversion. All this time we have been repeating the words 'know,'

'understand,' yet we do not know what knowledge is. 'Why, Socrates,

how can you argue at all without using them?' Nay, but the true hero

of dialectic would have forbidden me to use them until I had explained

them. And I must explain them now. The verb 'to know' has two senses,

to have and to possess knowledge, and I distinguish 'having' from

'possessing.' A man may possess a garment which he does not wear; or he

may have wild birds in an aviary; these in one sense he possesses, and

in another he has none of them. Let this aviary be an image of the mind,

as the waxen block was; when we are young, the aviary is empty; after

a time the birds are put in; for under this figure we may describe

different forms of knowledge;--there are some of them in groups, and

some single, which are flying about everywhere; and let us suppose

a hunt after the science of odd and even, or some other science. The

possession of the birds is clearly not the same as the having them in

the hand. And the original chase of them is not the same as taking them

in the hand when they are already caged.

This distinction between use and possession saves us from the absurdity

of supposing that we do not know what we know, because we may know in

one sense, i.e. possess, what we do not know in another, i.e. use. But

have we not escaped one difficulty only to encounter a greater? For how

can the exchange of two kinds of knowledge ever become false opinion?

As well might we suppose that ignorance could make a man know, or that

blindness could make him see. Theaetetus suggests that in the aviary

there may be flying about mock birds, or forms of ignorance, and we

put forth our hands and grasp ignorance, when we are intending to grasp

knowledge. But how can he who knows the forms of knowledge and the forms

of ignorance imagine one to be the other? Is there some other form of

knowledge which distinguishes them? and another, and another? Thus we go

round and round in a circle and make no progress.

All this confusion arises out of our attempt to explain false opinion

without having explained knowledge. What then is knowledge? Theaetetus

repeats that knowledge is true opinion. But this seems to be refuted by

the instance of orators and judges. For surely the orator cannot convey

a true knowledge of crimes at which the judges were not present; he

can only persuade them, and the judge may form a true opinion and truly

judge. But if true opinion were knowledge they could not have judged

without knowledge.

Once more. Theaetetus offers a definition which he has heard: Knowledge

is true opinion accompanied by definition or explanation. Socrates has

had a similar dream, and has further heard that the first elements are

names only, and that definition or explanation begins when they are

combined; the letters are unknown, the syllables or combinations

are known. But this new hypothesis when tested by the letters of the

alphabet is found to break down. The first syllable of Socrates' name

is SO. But what is SO? Two letters, S and O, a sibilant and a vowel,

of which no further explanation can be given. And how can any one

be ignorant of either of them, and yet know both of them? There is,

however, another alternative:--We may suppose that the syllable has a

separate form or idea distinct from the letters or parts. The all of the

parts may not be the whole. Theaetetus is very much inclined to adopt

this suggestion, but when interrogated by Socrates he is unable to

draw any distinction between the whole and all the parts. And if the

syllables have no parts, then they are those original elements of which

there is no explanation. But how can the syllable be known if the letter

remains unknown? In learning to read as children, we are first taught

the letters and then the syllables. And in music, the notes, which

are the letters, have a much more distinct meaning to us than the

combination of them.

Once more, then, we must ask the meaning of the statement, that

'Knowledge is right opinion, accompanied by explanation or definition.'

Explanation may mean, (1) the reflection or expression of a man's

thoughts--but every man who is not deaf and dumb is able to express his

thoughts--or (2) the enumeration of the elements of which anything is

composed. A man may have a true opinion about a waggon, but then, and

then only, has he knowledge of a waggon when he is able to enumerate

the hundred planks of Hesiod. Or he may know the syllables of the name

Theaetetus, but not the letters; yet not until he knows both can he be

said to have knowledge as well as opinion. But on the other hand he may

know the syllable 'The' in the name Theaetetus, yet he may be mistaken

about the same syllable in the name Theodorus, and in learning to read

we often make such mistakes. And even if he could write out all the

letters and syllables of your name in order, still he would only have

right opinion. Yet there may be a third meaning of the definition,

besides the image or expression of the mind, and the enumeration of the

elements, viz. (3) perception of difference.

For example, I may see a man who has eyes, nose, and mouth;--that will

not distinguish him from any other man. Or he may have a snub-nose and

prominent eyes;--that will not distinguish him from myself and you and

others who are like me. But when I see a certain kind of snub-nosedness,

then I recognize Theaetetus. And having this sign of difference, I have

knowledge. But have I knowledge or opinion of this difference; if I

have only opinion I have not knowledge; if I have knowledge we assume

a disputed term; for knowledge will have to be defined as right opinion

with knowledge of difference.

And so, Theaetetus, knowledge is neither perception nor true opinion,

nor yet definition accompanying true opinion. And I have shown that the

children of your brain are not worth rearing. Are you still in labour,

or have you brought all you have to say about knowledge to the birth? If

you have any more thoughts, you will be the better for having got rid of

these; or if you have none, you will be the better for not fancying that

you know what you do not know. Observe the limits of my art, which, like

my mother's, is an art of midwifery; I do not pretend to compare with

the good and wise of this and other ages.

And now I go to meet Meletus at the porch of the King Archon; but

to-morrow I shall hope to see you again, Theodorus, at this place.

...