170 Journal of Philology. of knowing how it was guarded by its author, recognises. Un- doubtedly : but we may at any rate follow the guidance of Plato in our interpretation of the theory, more especially as in this instance there is no trace of satire, but the doctrine and its consequences have all the appearance of being fairly, if not favourably, stated. Mr Grote has himself quoted Theast. p. 164. e, in support of this, to which add the whole defence of the theory put into the mouth of Protagoras, 165. e 168. c. 7rai's, J 2aj/t/}Tf, now yap veaviKcis to dv8p ^(^orjOrjKas. Plato States that it identifies sensation and knowledge a position which a high authority (Whewell, Phil. Ind. Sci. n. 288) tells us is " victoriously refuted." So far there was no novelty, and perhaps no mischief, in Protagoras' philosophy the earlier speculators in general confounded thought and sensation, Arist. de Anim. in. 3. na ot ye apxaiot. to (ppovelp Kai to alcrddveo-dai tovtov elvai (paaiv. But he went farther and identified <palveo-6ai and etvai, ' seeming' and * being,' Theffit. 166. c. d. e. 152. a. alib., which, though a convenient theory for those whose <paivopevrj o-ocpla would have been thereby converted into real wisdom, appears to be of questionable ten- dency when carried into the domain of ethics. In fact it leads to the principle above quoted, Theaet. 167. c, that whatever seems just and right to each city, [and of course to each indivi- dual, since every man is a measure to himself] that to her is right, as long as she sanctions it, or deems it to be so. Presently after (169. a.) the application of the theory to Theodorus' own science of mathematics is hinted at it would follow that every one is equally with Theodorus himself " the measure of diagrams :" as every thing is to every one what it seems, and there are no general principles of reasoning, mathematical (like moral) science becomes impossible and avrapiefj eKaorov els (ppovrja-iv iroiei 6 Acfyor, 169. d. In the Euthydemus, p. 284. c, another consequence of this theory is stated to have been held by Protagoras and his followers, oi apxf> llpa>Tay6papthe absurd paradox, viz. (afterwards maintained by Antisthenes) <s ovk tfrrw avrik<y<ivj that is, as Plato interprets it, <os ovk <m y^evdfj Ae'yeti/. Aristotle, Met. in. 4, (a pas- sage for which I am indebted to Ritter and Prellcr, Hist. Ph. 186) further explains this, and says that it is a necessary con- sequence of Protagoras' theory. According to it, a man, a wall, and a trireme will be all one and the same : " for if the man seems to any one not to be a trireme, it is plain that he is not a
