[Footnote 18: Analyt. Post. II. viii. p. 93, a. 3: [Greek: e)pei\ d' e)sti/n, ô(s e)/phamen, tau)to\n to\ ei)de/nai ti/ e)sti kai\ to\ ei)de/nai to\ ai)/tion tou= ei) e)/sti;] Ibid. a. 24: [Greek: o(/sa me\n ou)=n kata\ sumbebêko\s oi)/damen o(/ti e)/stin, a)nagkai=on mêdamô=s e)/chein pro\s to\ ti/ e)stin; **ou)de\ ga\r o(/ti e)/stin i)/smen; to\ de\ zêtei=n ti/ e)sti mê\ e)/chontas o(/ti e)/sti, mêde\n zêtei=n e)sti/n. kath' o(/sôn d' e)/chome/n ti, r(a=|on; ô(/ste ô(s e)/chomen o(/ti e)/stin, ou(/tôs e)/chomen kai\ pro\s to\ ti/ e)stin.] Compare Brentano, Ueber die Bedeutung des Seienden nach Aristoteles, p. 17.] [Footnote 19: Analyt. Post. II. viii. p. 93, a. 21. Themistius, p. 79, Speng.: [Greek: o(/sa de\ a)po\ tô=n oi)kei/ôn te kai\ e)x au)tou= tou= pra/gmatos, a)po\ tou/tôn ê)/dê r(a=|on ei)s to\ ti/ e)sti metabai/nomen.]] [Footnote 20: Ibid. p. 93, a. 30-b. 14.] Aristotle has thus shown how the Essence or Quiddity ([Greek: ti/ e)sti]) may become known in this class of cases. There is neither syllogism nor demonstration thereof, yet it is declared through syllogism and demonstration: though no demonstration thereof is possible, yet you cannot know it without demonstration, wherever there is an extraneous cause.[21] [Footnote 21: Ibid. b. 15-20: [Greek: ô(/ste sullogismo\s me\n tou= ti/ e)stin ou) gi/netai ou)d' a)po/deixis, dê=lon me/ntoi dia\ sullogismou= kai\ di' a)podei/xeôs.] Mr. Poste translates an earlier passage (p. 93, a. 5) in this very difficult chapter as follows (p. 107): "If one cause is demonstrable, another indemonstrable cause must be the intermediate; and the proof is in the first figure, and the conclusion affirmative and universal. In this mode of demonstrating the essence, we prove one definition by another, for the intermediate that proves an essence or a peculiar predicate must itself be an essence or a peculiar predicate. Of two definitions, then, one is proved and the other assumed; and, as we said before, this is not a demonstration but a dialectical proof of the essence." Mr. Poste here translates [Greek: logiko\s sullogismo/s] "dialectical proof." I understand it rather as meaning a syllogism, [Greek: tou= u(pa/rchein] simply (Top. I. v. p. 102, b. 5), in which all that you really know is that the predicate belongs to the subject, but in which you _assume_ besides that it belongs to the subject _essentially_. It is not a demonstration because, in order to obtain Essence in the conclusion, you are obliged to postulate Essence in your premiss. (See Alexander ad Topic. I. p. 263, Br.). You have therefore postulated a premiss which required proof as much as the conclusion.]