Dialogues

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, “Sophist” 250 following 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, c. 1), 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 (151 E), but, encouraged by Socrates, he rises to the occasion, and grows full of interest and enthusiasm about the great question. Like a youth (162 D), 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 (163 E), and of foreseeing the consequences of his own answers (154 D). 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” (15). 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 (148), but he is unable to attain a similar expression of knowledge in the abstract. Yet at length (185) 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 (VII 528 B). 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 (Müller). 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