[219] There still remains, then, the subject of genera and species, which we shall discuss more at large elsewhere, ¹ but here we shall deal with them concisely. If, on the one hand, they ² assert that genera and species are mental concepts, our criticisms of the ‟regent part” and of ‟presentation” refute them; whereas if they assign to them a substantiality of their own, how will they reply to this objection?

[220] If the genera exist, either they are equal in number to the species or else there is one genus common to all the species which are said to belong to it. If, then, the genera are equal in number to their species, there will no longer be a common genus to be divided into the species; while if it shall be said that the genus exists as one in all its species, then each species partakes of either the whole or a part of it. ³ But it certainly does not partake of the whole; for it is impossible that what is one real object should be equally included in separate things in such a way as to appear as a whole in each of those things in which it is said to exist. And if it partakes of a part, then, in the first place, all the genus will not, as they suppose, accompany the species, nor will ‟man” be ‟an animal” but a part of an animal—he will be substance, for example, but neither animate nor sensitive. ⁴

[221] Then, in the next place, all the species will be said to partake either of the same part of their genus or of different parts; but to partake of the same part is impossible for the reasons stated above; while if they partake of different parts, the species will be generically dissimilar one to another (which they will not admit), and each genus will be infinite because cut up into infinite sections (not into the species only but also into the particulars, since it is actually seen in these along with its species; for Dion ⁵ is said to be an animal as well as a man). But if these consequences are absurd, then not even by way of parts do the species partake of their genus, it being a unity.

[222] If, then, each several species partakes neither of the whole genus nor of a part of it, how can it be said that the one genus exists in all its parts so as to be actually divided into them? No one, probably, could make such a statement unless by concocting some imaginary entities, ⁶ which will be overturned, as the attacks of the Sceptics show, by the unsettled disputes of the Dogmatists themselves.

[223] Furthermore, there is this to be said. ⁷ The species are of this kind or of that kind: the genera of these species either are of both this kind and that kind, or of this kind but not of that kind, or neither of this kind nor of that kind. When, for instance, of the ‟somethings” (or particulars) some are corporeal others incorporeal, and some true others false, and some (it may be) white others black, and some very large others very small, and so on with the rest, the genus ‟something” (to take it for the sake of argument), which some regard as the summum genus, ⁸ will either be all these or some of them or none.

[224] But if the ‟something,” and the genus too, is absolutely none of them, the inquiry comes to an end. And if we should say that it is all of them, then, besides the impossibility of such a statement, each of the species and of the particulars wherein it exists will have to be all. For just as when the genus ‟animal” is, as they assert, ‟an animate sensitive substance,” each of its species is said to be substance and animate and sensitive, so likewise if the genus is both corporeal and incorporeal and false and true and black, it may be, and white and very small and very large, and all the rest, each of the species and of the particulars will be all these—which is contrary to observation. So this too is false.

[225] But if the genus is some of them only, the genus of these will not be the genus of the rest; if, for instance, the genus ‟something” is corporeal it will not be that of the incorporeal, and if the genus ‟animal” is rational it will not be that of the irrational, so that there is neither an incorporeal ‟something” nor an irrational animal, and so likewise with all other cases; and this is absurd. Therefore the genus cannot be either of both this and that kind, or of this kind but not of that, or of neither this kind nor that; and if this be so, neither does the genus exist at all.

And if one should say that the genus is potentially all things, ⁹ we shall reply that what is potentially something must also be actually something, as, for instance, no one can be potentially literary without being so actually. So too, if the genus is potentially all things, what, we ask them, is it actually? And thus we find that the same difficulties remain. For it cannot actually be all the contraries;

[226] nor yet can it be some of them actually and some only potentially —corporeal, for instance, actually and incorporeal potentially. For it is potentially that which it is capable of really being actually, but that which is actually corporeal is incapable of becoming incorporeal in actuality, so that if, for example, the genus ‟something” is actually corporeal it is not potentially incorporeal, and vice versa. It is impossible, therefore, for the genus to be some things actually and some only potentially. But if it is absolutely nothing actually, it has no substantial existence. Hence the genus, which they say they divide into the species, is nothing.

[227] And further, here is another point worthy of notice. Just as, because Alexander and Paris ¹⁰ are identical, it is impossible that the statement ‟Alexander walks” should be true when ‟Paris walks” is false, so also if ‟manhood” is identical for both Theon and Dion, the term ‟man” when introduced as an element in a judgement will cause the judgement to be equally true or false in the case of both. But this is not what we find; for when Dion is sitting and Theon walking, the judgement ‟man walks” is true when used of the one, but false of the other. Therefore the term ¹¹ ‟man” is not common to them both and the same for both but, if applicable at all, it is peculiar to one of the two.