latter converted into a formula and vindicated as a system. [Footnote 64: Among the commentators on the Categories of Aristotle, there were several whose principal object it was to propound all the most grave and troublesome difficulties which they could think of. Simplikius does not commend the style of these men, but he expresses his gratitude to them for the pains which they had taken in the exposition of the negative case, and for the stimulus and opportunity which they had thus administered to the work of affirmative exposition (Simplikius, Schol. ad Categ. Aristot. p. 40, a. 22-30; Schol. Brandis). David the Armenian, in his Scholia on the Categories (p. 27, b. 41, Brandis), defends the Topica of Aristotle as having been composed [Greek: gumnasi/as cha/rin, i(/na thlibome/nê ê( psuchê\ e)k tô=n e)ph' e(ka/tera e)picheirêma/tôn a)pogennê/sê| to\ tê=s a)lêthei/as phô=s.]] [Footnote 65: Sext. Emp. Pyrrh. Hypot. i. 8-12. [Greek: E)/sti de\ ê( skeptikê\ du/namis a)ntithetikê\ phainome/nôn te kai\ nooume/nôn kath' oi(ondê/pote tro/pon, a)ph' ê(=s e)rcho/metha, dia\ tê\n e)n toi=s a)ntikeime/nois pra/gmasi kai\ lo/gois i)sosthe/neian, to\ me\n prô=ton ei)s e)pochê\n to\ de\ meta\ tou=to ei)s a)taraxi/an . . . _i)sosthe/neian_ de\ le/gomen tê\n kata\ pi/stin kai\ a)pisti/an i)so/têta, ô(s mêde/na mêdeno\s prokei=sthai tô=n machome/nôn lo/gôn ô(s pisto/teron . . . susta/seôs de\ tê=s skeptikê=s e)stin a)rchê\ ma/lista _to\ panti\ lo/gô| lo/gon i)/son a)ntikei=sthai_.]] [Footnote 66: Plato, Phædrus, p. 261 D.] [Footnote 67: Plato, Parmenid. p. 136 C-D.] [Footnote 68: Sext. Emp. Pyrrh. Hyp. i. 20-212. [Greek: tê\n tô=n dogmatikô=n prope/teian--tê\n dogmatikê\n prope/teian.]] [Side-note: In order to understand fully the Platonic Antinomies, we ought to have before us the problems of the Megarics and others. Uselessness of searching for a positive result.] Schleiermacher has justly observed,[69] that in order to understand properly the dialectic manoeuvres of the Parmenides, we ought to have had before us the works of that philosopher himself, of Zeno, Melissus, Gorgias, and other sceptical reasoners of the age immediately preceding--which have unfortunately perished. Some reference to these must probably have been present to Plato in the composition of this dialogue.[70] At the same time, if we accept the dialogue as being (what it declares itself to be) a string of objections and dialectical problems, we shall take care not to look for any other sort of merit than what such a composition requires and admits. If the objections are forcible, the problems ingenious and perplexing, the purpose of the author is satisfied. To search in the dialogue for some positive result, not indeed directly enunciated but discoverable by groping and diving--would be to expect a species of fruit inconsistent with the nature of the tree. [Greek: Zêtô=n eu(rê/seis ou) r(o/don a)lla\ ba/ton.] [Footnote 69: Schleiermacher, Einleitung zum Parmen. pp. 97-99.]