We have already seen that the Aristotelian Ontology distinguishes one group of varieties of _Ens_ (or different meanings of the term _Ens_) as corresponding to the diversity of the ten Categories; while recognizing also another variety of _Ens_ as _Truth_, with its antithesis _Non-Ens_ as _Falsehood_.[1] The former group was dealt with in the preceding chapter; the latter will form the subject of the present chapter. In both, indeed, Ontology is looked at as implicated with Logic; that is, _Ens_ is considered as distributed under significant names, fit to be coupled in propositions. This is the common basis both of the Categoriæ and of the treatise De Interpretatione. The whole classification of the Categories rests on the assumption of the proposition with its constituent parts, and on the different relation borne by each of the nine _genera_ of predicates towards their common Subject. But in the Categoriæ no account was taken of the distinction between truth and falsehood, in the application of these predicates to the Subject. If we say of Sokrates, that he is fair, pug-nosed, brave, wise, &c., we shall predicate truly; if we say that he is black, high-nosed, cowardly, stupid, &c., we shall predicate falsely; but in each case our predicates will belong to the same Category--that of _Quale_. Whether we describe him as he now is, standing, talking, in the market-place at Athens; or whether we describe him as he is not, sitting down, singing, in Egypt--in both speeches, our predicates rank under the same Categories, _Jacere_, _Agere_, _Ubi_. No account is taken in the Categoriæ of the distinction between true and false application of predicates; we are only informed under what number of general heads all our predicates must be included, whether our propositions be true or false in each particular case. [Footnote 1: See above in the preceding chapter, p. 60.]