6.1–3 (42, 43, 44) form a single treatise on the genera of being. The first section 6.1 is devoted to a criticism of Aristotle, above all of his Categories, and of the Stoics. 6.2 continues with a positive theory taking as a starting point the view developed in Plato’s Sophist that there are five greatest genera of being. The third and final part 6.3 completes the account by using the results of the second part to offer an account of the genera applying to beings that undergo change.
6.1
§1. Plotinus begins by discussing the various positions taken by earlier thinkers on the question how many (genera of) beings there are, before concentrating on Aristotle (§§1–24); the final chapters then turn to the Stoics. The two central questions in discussing the Peripatetic view are: can one reduce the number of genera to ten? And: how does sensible being relate to intelligible being? Plotinus raises two problems: in any genus there is no prior and posterior, hence given a distinction between sensible and intelligible being, there cannot be genera of being. Secondly, there is only identity of name (‘homonymy’) between sensible beings and intelligible beings – when you say what each of them is, there are two different definitions.
§§2–3. The nature of substance. The fundamental problem that Plotinus raises here, repeated in the case of the other genera is the following: the things that are supposed to be substance are too diverse to fall under a single genus. For it should include sensible and intelligible being, form, matter and composite, individuals and species.
§§4–5. The nature of quantity. He repeats the criticism that there is no common characteristic uniting them in a genus. There are two species of quantity – continuous and discrete. But Plotinus wishes to establish which is really quantity and he comes to the conclusion that time and space are only accidentally quantities, and that only number is essentially quantity.
§§6–9. The nature of relatives; here too a problem is the coherence of the genus. But even prior to this, the question about the being of relatives has to be settled. §7 pursues a thesis that there are only relatives for us, in that they do not affect the relata. §8 returns to the question of the being of relatives – they are not bodies, but incorporeal. But they are of different kinds. §9 discusses three kinds of principles of relatives – the relation that brings about (1) an activity, (2) participation, (3) sensation, states and measures.
§§10–12. The nature of quality. On the basis of four types of quality distinguished by Aristotle: states, disposition, capacity, and figure, Plotinus argues that quality does not form a coherent genus. There is no one feature common to all types. In §10 he argues that in fact the distinctions between the four types are not tenable, and in §12 he sketches a new, provisional typology, depending on whether the qualities are those of body and soul, corresponding to activities, and harmful or beneficial.
§13. The nature of the ‘when’, which insofar as it collects adverbs of time is a genuine genus. However, Plotinus tries to show that it can be reduced, namely to quantity in that time is a quantity.
§14. The nature of the ‘where’, which provides answers to questions formulated with ‘where’? Because it can be reduced to place, it is not a genus in its own right. The parallel between the where and the when is extended to include the idea that neither is simple in the way that a genus should be, since they indicate parts of place and time. Both can in fact be considered as relatives.
§§15–22. The discussion of producing change and being affected takes up §§15–22. In fact, Plotinus insists on discussing the activity by which something acts. He then moves on to refute Aristotle’s definition of motion as an incomplete activity. For it is complete, in every instant, is continuous, and not infinitely divisible. Once motion has been assimilated to activity, the question arises whether acting and being affected are not in fact simply relatives. Plotinus in fact considers producing change and being affected as species of motion (§18): some activities relate to something being affected, others do not. Only the former are changes, and the latter are activities. Activities can then be distinguished into locomotion and thought. If the change in being comes from its own being, that is acting, if from that of another being, then it is being affected. However (§19), the distinction between acting and being affected is not clear-cut: cutting for example includes both. Being affected does not merely designate the process of becoming worse. Finally, in §§21–22 Plotinus argues that acting and being affected are not genera of being. If they differ from one another, then they are changes, more exactly alterations. If they are merely two aspects of one change, then they are both merely relatives. However, those acts which do not relate to other things should not be considered as acting at all; so all acting is in fact relative.
§§23–24. The nature of having, providing Plotinus with a variety of criticisms, above all why such a restricted notion should be a genus at all. Similarly, he argues against the position (§24), that many items placed in this genus can easily be placed in other genera.
§§25–30. Attack on the Stoic notion of genera. First, he attacks the logical mistakes he sees in the choice of genera, and secondly he attacks Stoic corporealism: all the genera are bodies, except lekta, ‘sayables’. They distinguish four primary genera of being, that is, of body – the substrate, the thing qualified, the way of being, and the way of being related to other things. Common to all of these is being ‘something’. Plotinus criticizes this notion in that this genus encompasses both bodies and incorporeals. And a genus can only be differentiated into species using differences not lying in the genus itself. And it finally contravenes the law of the excluded middle – in including both beings and non-beings (incorporeals). Their notion of substrate combines that of matter and body – and the former is prior to the latter, and so cannot be in one genus with it. Furthermore, matter is a principle, not a genus.
6.2 (43) tackles the question of what the genera of being are, and the answer Plotinus develops is based on the five greatest genera from Plato’s Sophist. The first matter to be settled is what a genus of being is (§§1–3). They must be primary, that is subordinate neither to one another nor to any other genus.
6.2
§1. The Platonic genera.
§2. Being is one-many.
§3. The genera of being are secondary, caused to be by the One.
§4. And they are intelligible being, rather than becoming, that is, they are not body.
§5. Soul, on the other hand, is a principle producing things, by being the source of their expressed principles (λόγοι).
§6. While soul is one, in fact one soul, it is the source of the forms producing all bodies.
§7. In soul, we find Being, Life and thinking, which in terms of the greatest genera provide Plotinus with Being, Motion, and Stability. These genera are situated in Intellect: its mode of thinking is to be understood in terms of Being, Motion, and Stability.
§8. Since each of these is identical to itself, and different from the others, two further genera are added: Identity and Difference.
§§9–18. These five genera cannot be augmented, especially not by the One, which is not a genus, nor by quantity (§13), nor quality (§§14–15), nor the relative or other Peripatetic genera (§16). Other candidates are also excluded: the Good (§17), the Beautiful and the virtues (§18).
§19. But how are the greatest genera related to their species? Being, i.e., Intellect, produces the particular intellects, and also soul.
§20. The way the particular intellects are produced by Intellect.
§21. Intellect also produces particular things.
§22. Finally, Plotinus relates his account back to that in Plato – Timaeus 39E, Parmenides 144BC, Philebus 16E.
6.3 (44) proceeds to apply the lessons of 6.2 to things that come to be. What does becoming have in common with being? There are analogously the same genera, primarily in being, and secondarily in coming to be. §2 proceeds to argue against an Aristotelian view of what is common between the greatest genera and Aristotelian substance. §3 tries to deduce the five primary genera applicable to becoming: substance, relatives, quantity, quality, and motion. The following chapters discuss these five genera: substance §§4–10, quantity §§11–15, quality §§16–20, motion §§21–27, relatives §28.
6.3
§1. What does becoming have in common with being? There are analogously the same genera, primarily in being, and secondarily in coming to be.
§2. Argument against an Aristotelian view of what is common between the greatest genera and Aristotelian substance.
§3. Attempt to deduce the five primary genera applicable to becoming: substance, relatives, quantity, quality, and motion. The following sections discuss these five genera: substance §§4–10, quantity §§11–15, quality §§16–20, motion §§21–27, relatives §28.
§4. Form, matter, and composite are substance. Substance is not merely the substrate of attributes, it is the source of other things, and of production; in short that because of which there are other things.
§5. In the intelligibles, being the substrate is said differently, namely homonymously. Not being in anything else can also be said of time or place.
§6. In the case of the elements, their being is simple, whereas in that of attributes such as pale, being is accidental.
§7. If sensible beings have their being from matter, the question arises where it acquires its being from, since it is not primary.
§8. (Sensible) substance is not the elements but a bundle of qualities or forms in matter.
§9. Sensible substances are then more or less material – elements, plants, animals – their species, both individuals and universals. Individuals are prior to us, in that they are more knowable to us, but naturally prior are those which are more general, i.e., species.
§10. It is possible to divide substances by the coupling of simple qualities or else by a quality, i.e., their form in the case of organic substances.
§11. The quantity that makes instances of quantity lies in both number and magnitude.
§12. There are contraries in quantity – large–small, many–few. There is quantity when a unit or point is extended. The magnitude of the quantity depends on how long the extension is.
§13. The continuous magnitude is to be distinguished from the discrete one by the possession of a boundary. Line, plane, and solid are species of magnitude.
§14. Straight line is for example a species of line, and hence of quantity. Even if magnitudes are distinguished by qualities, they remain magnitudes.
§15. Sameness in magnitude is quality, but the differentiae of quantity should really be placed along with the things they are differentiae of. So too the differentiae of substances are rather substances than qualities.
§16. A quality is what is said of something, apart from what is its substance, and indicates what kind of a thing it is, such as virtue or baseness in the soul. Some such characteristics are in the intelligible, and some in the sensible. Crafts relating to body are sensible qualities, whilst other crafts are intelligible.
§17. So some qualities are psychical and some are corporeal. Qualities here can also be distinguished by the different kinds of sense-perception. That leaves us the question of how qualities falling under one form of sense-perception, e.g. pale and dark, differ.
§18. But there are no differentiae of differentiae; and qualities are differentiae.
§19. Privations of qualities are qualities; but the process of acquiring a quality is not.
§20. In some cases, there is contrariety between qualities when there is a greatest change between the two termini. In other cases there is contrariety where there is nothing mediating.
§21. Motion cannot be reduced to any other genus. Coming to be is not a motion, since motion presupposes that something already is. It includes as a species change, namely that motion which goes beyond what something is.
§22. Alteration is motion when this is to something other. Motion generally speaking is a path from capacity to what it is capable of. It is a woken form, rather than a static one. What is common to all motion is something’s not being in the identical state it was before.
§23. In sensible things, motion comes from outside the thing moved. The motion is then in the thing moved. The quality of a motion is determined not only by what it is in, but also by what brought it about, and what it occurs through.
§24. What unifies cases of local motion up and down is something being carried to its natural place. Local motions can also be distinguished by the geometrical form of the course.
§25. Combination and separation are either forms of local motion (withdrawal or approach of one thing from or to another), or else mixing and its contrary; in the second case there is local motion but something else supervenes. And combination and separation cannot be reduced to alteration, although this too is initiated by combination and separation in many cases.
§26. Motions can be divided according to whether they are caused by soul or not, or according to whether they are caused by nature, craft, or choice.
§27. Repose is the removal of motion, in things whose nature it is to move, whereas stability among the intelligibles is entirely compatible with motion.
§28. Producing motion and being affected can be reduced to motion. And the other genera have been reduced to these ones.