Poetical vein predominant in some compositions, but not in all 343 Form of dialogue--universal to this extent, that Plato never speaks in his own name 344 No one common characteristic pervading all Plato's works _ib._ The real Plato was not merely a writer of dialogues, but also lecturer and president of a school. In this last important function he is scarcely at all known to us. Notes of his lectures taken by Aristotle 346 Plato's lectures De Bono obscure and transcendental. Effect which they produced on the auditors 347 They were delivered to miscellaneous auditors. They coincide mainly with what Aristotle states about the Platonic Ideas 348 The lectures De Bono may perhaps have been more transcendental than Plato's other lectures 349 Plato's Epistles--in them only he speaks in his own person _ib._ Intentional obscurity of his Epistles in reference to philosophical doctrine 350 Letters of Plato to Dionysius II. about philosophy. His anxiety to confine philosophy to discussion among select and prepared minds 351 He refuses to furnish any written, authoritative exposition of his own philosophical doctrine 352 He illustrates his doctrine by the successive stages of geometrical teaching. Difficulty to avoid the creeping in of error at each of these stages 353 No written exposition can keep clear of these chances of error 355 Relations of Plato with Dionysius II. and the friends of the deceased Dion. Pretensions of Dionysius to understand and expound Plato's doctrines _ib._ Impossibility of teaching by written exposition assumed by Plato; the assumption intelligible in his day 357 Standard by which Plato tested the efficacy of the expository process.--Power of sustaining a Sokratic cross-examination 358 Plato never published any of the lectures which he delivered at the Academy _ib._ Plato would never publish his philosophical opinions in his own name; but he may have published them in the dialogues under the name of others 360 Groups into which the dialogues admit of being thrown 361 Distribution made by Thrasyllus defective, but still useful--Dialogues of Search, Dialogues of Exposition _ib._ Dialogues of Exposition--present affirmative result. Dialogues of Search are wanting in that attribute 362 The distribution coincides mainly with that of Aristotle--Dialectic, Demonstrative 363 Classification of Thrasyllus in its details. He applies his own principles erroneously 364 The classification, as it would stand, if his principles were applied correctly 365 Preponderance of the searching and testing dialogues over the expository and dogmatical 366 Dialogues of Search--sub-classes among them recognised by Thrasyllus--Gymnastic and Agonistic, &c. _ib._ Philosophy, as now understood, includes authoritative teaching, positive results, direct proofs _ib._