Theaetetus
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THEAETETUS
By Plato
Translated by Benjamin Jowett
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,