The above considerations- to which others, doubtless, might be added- suffice to show that these five are primary genera. But that they are the only primary genera, that there are no others, how can we be confident of this? Why do we not add unity to them? Quantity? Quality? Relation, and all else included by our various forerunners? As for unity: If the term is to mean a unity in which nothing else is present, neither Soul nor Intellect nor anything else, this can be predicated of nothing, and therefore cannot be a genus. If it denotes the unity present in Being, in which case we predicate Being of unity, this unity is not primal. Besides, unity, containing no differences, cannot produce species, and not producing species, cannot be a genus. You cannot so much as divide unity: to divide it would be to make it many. Unity, aspiring to be a genus, becomes a plurality and annuls itself. Again, you must add to it to divide it into species; for there can be no differentiae in unity as there are in Substance. The mind accepts differences of Being, but differences within unity there cannot be. Every differentia introduces a duality destroying the unity; for the addition of any one thing always does away with the previous quantity. It may be contended that the unity which is implicit in Being and in Motion is common to all other things, and that therefore Being and unity are inseparable. But we rejected the idea that Being is a genus comprising all things, on the ground that these things are not beings in the sense of the Absolute Being, but beings in another mode: in the same way, we assert, unity is not a genus, the Primary Unity having a character distinct from all other unities. Admitted that not everything suffices to produce a genus, it may yet be urged that there is an Absolute or Primary Unity corresponding to the other primaries. But if Being and unity are identified, then since Being has already been included among the genera, it is but a name that is introduced in unity: if, however, they are both unity, some principle is implied: if there is anything in addition , unity is predicated of this added thing; if there is nothing added, the reference is again to that unity predicated of nothing. If however the unity referred to is that which accompanies Being, we have already decided that it is not unity in the primary sense. But is there any reason why this less complete unity should not still possess Primary Being, seeing that even its posterior we rank as Being, and "Being" in the sense of the Primary Being? The reason is that the prior of this Being cannot itself be Being- or else, if the prior is Being, this is not Primary Being: but the prior is unity; . Furthermore, unity, abstracted from Being, has no differentiae. Again, even taking it as bound up with Being: If it is a consequent of Being, then it is a consequent of everything, and therefore the latest of things: but the genus takes priority. If it is simultaneous with Being, it is simultaneous with everything: but a genus is not thus simultaneous. If it is prior to Being, it is of the nature of a Principle, and therefore will belong only to Being; but if it serves as Principle to Being, it is not its genus: if it is not genus to Being, it is equally not a genus of anything else; for that would make Being a genus of all other things. In sum, the unity exhibited in Being on the one hand approximates to Unity-Absolute and on the other tends to identify itself with Being: Being is a unity in relation to the Absolute, is Being by virtue of its sequence upon that Absolute: it is indeed potentially a plurality, and yet it remains a unity and rejecting division refuses thereby to become a genus.

We divide, therefore, the genus of what is proposed for consideration into the species contained in it; as, in the case of man, we divide animal,...

With respect to your inquiry, “ what the peculiarities are in each of the more excellent genera, by which they are separated from each other? ” if...

The genera of all things company with their own species; so that the genus is a class in its entirety, the species is part of a genus. The genus of th...

Accordingly we must first take the genus, in which are the points that are nearest those above; and after this the next difference. And the...

Accordingly, in the larger definitions the number of the species that are discovered are in the ten Categories; and in the least, the principal...

To which may be added, that it is dreadfully absurd to ascribe to bodies a principal power of giving a specific distinction to the first causes of the...

Since, however, the order of all the Gods is profoundly united, and the first and second genera of them, and all the multitude which is spontaneously...

5. “Whoever, therefore, is able to analyze all the genera which are contained under one and the same principle, and again to compose and con-numerate...

The latter, then, which are being made,—either by Gods, or daimons, or by men,—are species all most closely like to their own several genera. For that...

The species is always contemplated in a part. On the other hand, however, if a thing is part of another, it will not be also a species. For the hand...

In short, whether you think that there is one genus of the Gods, one of dæmons, and in a similar manner of heroes, and souls essentially incorporeal;...

Whence both these divisions are to be rejected, and only the division of the genus into species is approved, by which both the identity that is in...

This then is sufficient on these matters, let us now advance to the purpose of the discourse by unfolding, to the best of our ability, the kindred...

You must not, therefore, think that this division is the peculiarity of powers or energies, or of essence; nor assuming it separately, must you...

Now in definitions, difference is assumed, which, in the definition, occupies the place of sign. The faculty of laughing, accordingly, being added to...

Thus thou may understand what manner of being the Deity is, and how the three Persons in the Deity are. Thou must not liken the Deity to any image;...

In these three species or qualities stands the corporeal being, or the creatural being of all creatures in heaven and in this world, whether it be...

Now every single class of living thing, Asclepius, of whatsoever kind, or it be mortal or be rational, whether it be endowed with soul, or be without...

For, after dividing "the animal" into mortal and immortal, then into terrestrial and aquatic; and the terrestrial again into those who fly and those w...

It is necessary, therefore, to admit a thing of this kind in partial souls. For such as is the life which the soul received, prior to its insertion...