"Gross ignorance descries no difficulties. Imperfect knowledge finds them out and struggles with them. It must be perfect knowledge that overcomes them." Of the three different mental conditions here described, the first is that against which Sokrates made war, _i.e._ real ignorance, and false persuasion of knowledge, which therefore descries no difficulties. The second, or imperfect knowledge struggling with difficulties, is represented by the Platonic negative dialogues. The third--or perfect knowledge victorious over difficulties--will be found in the following pages marked by the character [Greek: to\ du/nasthai lo/gon dido/nai kai\ de/chesthai]. You do not possess "perfect knowledge," until you are able to answer, with unfaltering promptitude and consistency, all the questions of a Sokratic cross-examiner--and to administer effectively the like cross-examination yourself, for the purpose of testing others. [Greek: O(\lôs de\ sêmei=on tou= ei)do/tos to\ du/nasthai dida/skein e)/stin.] (Aristotel. Metaphys. A. 981, b. 8.) Perfect knowledge, corresponding to this definition, will not be found manifested in Plato. Instead of it, we note in his latter years the lawgiver's assumed infallibility.] Moreover, I deal with each dialogue as a separate composition. Each represents the intellectual scope and impulse of a peculiar moment, which may or may not be in harmony with the rest. Plato would have protested not less earnestly than Cicero,[5] against those who sought to foreclose debate, in the grave and arduous struggles for searching out reasoned truth--and to bind down the free inspirations of his intellect in one dialogue, by appealing to sentence already pronounced in another preceding. Of two inconsistent trains of reasoning, both cannot indeed be true--but both are often useful to be known and studied: and the philosopher, who professes to master the theory of his subject, ought not to be a stranger to either. All minds athirst for reasoned truth will be greatly aided in forming their opinions by the number of points which Plato suggests, though they find little which he himself settles for them finally. [Footnote 5: Cicero, Tusc. Disp. v. 11, 38. The collocutor remarks that what Cicero says is inconsistent with what he (Cicero) had written in the fourth book De Finibus. To which Cicero replies:-- "Tu quidem tabellis obsignatis agis mecum, et testificaris, quid dixerim aliquando aut scripserim. Cum aliis isto modo, qui legibus impositis disputant. Nos in diem vivimus: quodcunque nostros animos probabilitate percussit, id dicimus: itaque soli sumus liberi."]