This is a sort of article in a Philosophical Dictionary, tracing the various derivative senses of two very usual correlative phrases; and there is another article in the fourth book of the Metaphysica, where the derivations of the same terms are again traced out, though by roads considerably different.[148] The two terms are relatives; _Prius_ implies a _Posterius_, as _Simul_ implies another _Simul_; and it is an useful process to discriminate clearly the various meanings assigned to each. Aristotle has done this, not indeed clearly nor consistently with himself, but with an earnest desire to elucidate what he felt to be confused and perplexing. Yet there are few terms in his philosophy which are more misleading. Though he sets out, plainly and repeatedly the primary and literal sense of Priority, (the temporal or real), as discriminated from the various secondary and metaphorical senses, nevertheless when he comes to employ the term _Prius_ in the course of his reasonings, he often does so without specifying in which sense he intends it to be understood. And as the literal sense (temporal or real priority) is the most present and familial to every man's mind, so the term is often construed in this sense when it properly bears only the metaphorical sense. The confusion of logical or emotional priority (priority either in logical order of conception, or in esteem and respect) with priority in the order of time, involving separability of existence, is a frequent source of misunderstanding in the Aristotelian Physics and Metaphysics. The order of logical antecedence and sequence, or the fact of logical coexistence, is of great importance to be understood, with a view to the proof of truth, to the disproof of error, or to the systematization of our processes of thought; but we must keep in mind that what is prior in the logical order is not for that reason prior in temporal order, orf separable in real existence, or fit to be appealed to as a real Cause or Agent.[149] [Footnote 148: Aristot. Metaphys. [Greek: D]. p. 1018, b. 11-p. 1019, a. 12. The article in the Metaphysica is better and fuller than that in the Categoriæ. In this last, _Order in Place_ receives no special recognition, while we find such recognition in the Metaphysica, and we find also fuller development of the varieties of the logical or intellectual _Prius_.] [Footnote 149: In the language of Porphyry, [Greek: prou+phe/stêke] (priority in real existence) means nothing more than [Greek: proe+pinoei=tai] (priority in the order of conception), Eisagoge, cc. xv., xvi.; Schol. Br. p. 6, a. 7-21.] CHAPTER IV. DE INTERPRETATIONE. In the preceding chapter I enumerated and discussed what Aristotle calls the Categories. We shall now proceed to the work which stands second in the aggregate called the Organon--the treatise De Interpretatione.