_Sokr._--You seem absorbed in thought, Alkibiades, and not unreasonably. In supplicating the Gods, caution is required not to pray for gifts which are really mischievous. The Gods sometimes grant men's prayers, even when ruinously destructive; as they granted the prayers of Oedipus, to the destruction of his own sons. _Alk._--Oedipus was mad: what man in his senses would put up such a prayer? _Sokr._--You think that madness is the opposite of good sense or wisdom. You recognise men wise and unwise: and you farther admit that every man must be one or other of the two,--just as every man must be either healthy or sick: there is no third alternative possible? _Alk._--I think so. _Sokr._--But each thing can have but one opposite:[27] to be unwise, and to be mad, are therefore identical? _Alk._--They are. _Sokr._--Wise men are only few, the majority of our citizens are unwise: but do you really think them mad? How could any of us live safely in the society of so many mad-men? _Alk._--No: it cannot be so: I was mistaken. _Sokr._--Here is the illustration of your mistake. All men who have gout, or fever, or ophthalmia are sick; but all sick men have not gout, or fever, or ophthalmia. So, too, all carpenters, or shoemakers, or sculptors, are craftsmen; but all craftsmen are not carpenters, or shoemakers, or sculptors. In like manner, all mad men are unwise; but all unwise men are not mad. _Unwise_ comprises many varieties and gradations of which the extreme is, being mad: but these varieties are different among themselves, as one disease differs from another, though all agree in being disease and one art differs from another, though all agree in being art.[28] [Footnote 27: Plato, Alkib. ii. p. 139 B. [Greek: Kai\ mê\n du/o ge u(penanti/a e(ni\ pra/gmati pô=s a)\n ei)/ê?] That each thing has one opposite, and no more, is asserted in the Protagoras also, p. 192-193.] [Footnote 28: Plato, Alkib. ii. p. 139-140 A-B. [Greek: Kai\ ga\r oi( pure/ttontes pa/ntes nosou=sin, ou) me/nntoioi( nosou=ntes pa/ntes pure/ttousin ou)de\ podagrô=sin ou)de/ ge o)phthalmiô=sin; a)lla\ no/sos me\n pa=n to\ toiou=to/n e)sti, diaphe/rein de/ phasin ou(\s dê\ kalou=men i)atros tê\n a)pergasi/an au)tô=n; ou) ga\r pa=sai ou)/te o(/moiai ou)/te o(moi/ôs diapra/ttontai, a)lla\ kata\ tê\n au)tê=s du/namin e(ka/stê.]] [Side-note: Relation between a generic term, and the specific terms comprehended under it, was not then familiar.] (We may remark that Plato here, as in the Euthyphron, brings under especial notice one of the most important distinctions in formal logic--that between a generic between a term and the various specific terms comprehended under it. Possessing as yet no technical language for characterising this distinction, he makes it understood by an induction of several separate but analogous cases. Because the distinction is familiar now to instructed men, we must not suppose that it was familiar then.)