The close of the Parmenides, as it stands here, may be fairly compared to the enigma announced by Plato in his Republic--"A man and no man, struck and did not strike, with a stone and no stone, a bird and no bird, sitting upon wood and no wood".[110] This is an enigma, propounded for youthful auditors to guess: stimulating their curiosity, and tasking their intelligence to find it out. As far as I can see, the puzzling antinomies in the Parmenides have no other purpose. They drag back the forward and youthful Sokrates from affirmative dogmatism to negative doubt and embarrassment. There is however this difference between the enigma in the Republic, and the Antinomies in the Parmenides. The constructor of the enigma had certainly a preconceived solution to which he adapted the conditions of his problem: whereas we have no sufficient ground for asserting that the author of the Antinomies had any such solution present or operative in his mind. How much of truth Plato may himself have recognised, or may have wished others to recognise, in them, we have no means of determining. We find in them many equivocal propositions and unwarranted inferences--much blending of truth with error, intentionally or unintentionally. The veteran Parmenides imposes the severance of the two, as a lesson, upon his youthful hearers Sokrates and Aristoteles. [Footnote 110: Plato, Republ. v. 479 C. The allusion was to an eunuch knocking down a bat seated upon a reed. [Greek: Ai)no/s tis e)/stin ô(s a)nê/r te kou)k a)nê/r, O)/rnitha/ te kou)k o)/rnith' i)dô/n te kou)k i)dô/n, E)pi\ xu/lou te kou) xu/lou kathême/nên Li/thô| te kou) li/thô| ba/loi te kou) ba/loi.] I read with astonishment the amount of positive philosophy which a commentator like Steinhart extracts from the concluding enigma of the Parmenides, and which he even affirms that no attentive reader of the dialogue can possibly miss (Einleitung zum Parmenides, pp. 302-303).] CHAPTER XXVIII. THEÆTETUS. [Side-note: Subjects and personages in the Theætêtus.] In this dialogue, as in the Parmenides immediately preceding, Plato dwells upon the intellectual operations of mind: introducing the ethical and emotional only in a partial and subordinate way. The main question canvassed is, What is Knowledge--Cognition--Science? After a long debate, turning the question over in many distinct points of view, and examining three or four different answers to the question--all these answers are successively rejected, and the problem remains unsolved.