[Footnote 110: Metaphysic. [Greek: D]. p. 1020, b. 13: [Greek: schedo\n dê\ kata\ du/o tro/pous le/goit' a)\n to\ poio/n, kai\ tou/tôn e(/na to\n kuriô/taton; prô/tê me\n ga\r poiotê\s ê( tê=s ou)si/as diaphora/.] Compare Physic. v. p. 226, a. 27. See Trendelenburg, Kategorienlehre, pp. 56, 93. The remarks of the different expositors (contained in Scholia, pp. 52, 53, 54, Brand.), are interesting upon the ambiguous position of Differentia, in regard to Substance and Quality. It comes out to be Neither and Both--[Greek: ou)de/tera kai\ a)mpho/tera] (Plato, Euthydemus, p. 300 C.). Dexippus and Porphyry called it something intermediate between [Greek: ou)si/a] and [Greek: poio/tês], or between [Greek: ou)si/a] and [Greek: sumbebêko/s].] We see, accordingly, that neither is the line of demarcation between the Category of Substance or Essence and the other Categories so impassable, nor the separability of it from the others so marked as some thinkers contend. Substance is represented by Aristotle as admitting of more and less, and as graduating by successive steps down to the other Categories; moreover, neither in its complete manifestation (as First Substance), nor in its incomplete manifestation (as Second Substance), can it be explained or understood without calling in the other Categories of Quantity, Quality, and Relation. It does not correspond to the definition of _Substantia_ given by Spinoza--"_quod in se est et per se concipitur_." It can no more be conceived or described without some of the other Categories, than they can be conceived or described without it. Aristotle defines it by four characteristics, two negative, and two positive. It cannot be predicated of a Subject: it cannot inhere in a Subject: it is, at bottom, the **Subject of all Predicates: it is _Unum numero_ and indivisible.[111] Not one of these four determinations can be conceived or understood, unless we have in our minds the idea of other Categories and its relation to them. Substance is known only as the Subject of predicates, that is, relatively to them; as they also are known relatively to it. Without the Category of Relation, we can no more understand what is meant by a Subject than what is meant by a Predicate. The Category of Substance, as laid out by Aristotle, neither exists by itself, nor can be conceived by itself, without that of Relation and the generic notion of Predicate.[112] All three lie together at the bottom of the analytical process, as the last findings and residuum. [Footnote 111: Categor. p. 2, a. 14, b. 4; p. 3, b. 12.] [Footnote 112: Aristotle gives an explanation of what he means by [Greek: kath' au(to/--kath' au(ta/], in the Analytic. Post. I. iv. p. 73, a. 34, b. 13. According to that explanation it will be necessary to include in [Greek: to\ kath' au(to\] of the Category [Greek: Ou)si/a], all that is necessary to make the definition or explanation of that Category understood.