No doubt Isocrates himself professed to give a practical training for public life; but he states here what he repeats with more emphasis in a later writing:[200] ‘For distinction either in speech or in action, or in any other work, there are three requisites: natural aptitude, theoretical training, and practical experience.... Of these the first is indispensable, and by far the most important.’ The Sophists claimed to dispense with the first, and this is the ground of the philosopher’s quarrel with them. The third section of the speech, following naturally on the second, deals with writers of technical guides to rhetoric (τέχναι). ‘They profess to teach litigation, choosing for themselves this offensive title which would be more appropriate in the mouths of their detractors. They are worse than those who wallow in the mire of “eristic,” for they at least pretend to be concerned with virtue and moderation, while those whom we are considering now undertake only to teach men to be busy-bodies from motives of base covetousness.’[201] Here again Isocrates, who himself composed an ‘Art’ of rhetoric, does not condemn all who may try to teach the subject; his complaint is that the majority of such teachers have confined themselves to the ignoble branch of the profession. This criticism is obviously a valid one, and is echoed by Aristotle, who declares that speaking before a public assembly is less knavish (κακοῦργον) than speaking in a law-court.[202] The speech entitled _On the Antidosis_ is really Isocrates’ defence of his life and profession. In 355 B.C. he was challenged by one Megacleides to undertake the trierarchy, or else to accept an _antidosis_, or exchange of properties. The matter was the subject of a trial, in consequence of which Isocrates performed the trierarchy. Some time—perhaps two years—later, he wrote this speech, which is of no historical importance, since even the name of the plaintiff, Lysimachus, is fictitious. The introduction (§§ 1-13) makes it clear that the law-suit is only introduced for the sake of local colour. The speech itself begins with a semblance of forensic form in § 14, but the pretence is very soon dropped. The cloak is resumed in the Epilogue (§§ 320-323); but the greatest part of the speech has nothing to do with any trial, real or imaginary. The treatise, as we may call it, falls into two parts: in §§ 14-166 the writer defends his own character; in §§ 167-319 he defends his system of education.