[Footnote 45: Plato, Parmenid. p. 136 D. [Greek: ei) me\n ou)=n plei/ous ê)=men, ou)k a)\n a)/xion ê)=n dei=sthai; _a)prepê= ga\r ta\ toiau=ta pollô=n e)nanti/on le/gein_, a)/llôs te kai\ têlikou/tô|; a)gnoou=si ga\r oi( polloi\ o(/ti a)/neu tau/tês tê=s dia\ pa/ntôn diexo/dou kai\ pla/nês, a)du/naton e)ntucho/nta tô=| a)lêthei= nou=n schei=n.] Hobbes remarks (Computatio sive Logica, i. 3, 12): "Learners ought to go through logical exercises silently and by themselves: for it will be thought both ridiculous and absurd, for a man to use such language publicly". Proklus tells us, that the difficulty of the [Greek: gumnasi/a], here set out by the Platonic Parmenides, is so prodigious, that no one after Plato employed it. (Prok. ad Parmen. p. 801, Stallb.)] [Side-note: Parmenides elects his own theory of the _Unum_, as the topic for exhibition--Aristoteles becomes respondent.] It is especially on this ground--the small number and select character of the auditors--that Parmenides suffers himself to be persuaded to undertake what he calls "amusing ourselves with a laborious pastime".[46] He selects, as the subject of his dialectical exhibition, his own doctrine respecting the One. He proceeds to trace out the consequences which flow, first, from assuming the affirmative thesis, _Unum Est_: next, from assuming the negative thesis, or the Antithesis, _Unum non Est_. The consequences are to be deduced from each hypothesis, not only as regards _Unum_ itself, but as regards _Cætera_, or other things besides _Unum_. The youngest man of the party, Aristoteles, undertakes the duty of respondent. [Footnote 46: Plato, Parmenid. p. 137 A. [Greek: dei= ga\r chari/zesthai, _e)peidê\_ kai\ o(\ Zê/nôn le/gei, _au)toi/ e)smen_ . . . ê)\ bou/lesthe _e)peidê/per dokei= pragmateiô/dê paidia\n pai/zein_,] &c.] [Side-note: Exhibition of Parmenides--Nine distinct deductions or Demonstrations, first from _Unum Est_--next from _Unum non Est_.] The remaining portion of the dialogue, half of the whole, is occupied with nine distinct deductions or demonstrations given by Parmenides. The first five start from the assumption, _Unum Est_: the last four from the assumption, _Unum non Est_. The three first draw out the deductions from _Unum Est_, in reference to _Unum_: the fourth and fifth draw out the consequences from the same premiss, in reference to _Cætera_. Again, the sixth and seventh start from _Unum non Est_, to trace what follows in regard to _Unum_: the eighth and ninth adopt the same hypothesis, and reason it out in reference to _Cætera_. [Side-note: The Demonstrations in antagonising pairs, or Antinomies. Perplexing entanglement of conclusions given without any explanation.]