The remaining twenty-five chapters of the present tract are devoted to the discussion of the proposed five categories of the sensible realm. In accordance with the role which they play in the Plotinian theory, the pro portional length devoted to each of them is as follows:
(a) Substance, seven chapters; (b) Motion, seven chapters; (c) Quantity, five chapters; (d) Quality, five chapters; (e) Relation, one chapter.
They are considered and discussed in the following order: substance, quantity, quality, motion and relation.
As expected, priority is given to the category of the "so-called" substance in respect to both length and order. After it comes the Ploti nian category of motion which, as a new category, needed to be carefully considered and established. With regard to the categories of quantity and quality nothing is unexpected. It is surprising, however, that the discus sion of relation has been compressed into one small chapter, in a way which contrasts sharply with the treatment given to the same category in the first tract. How is this discrepancy to be explained?
Without intending to offer a full explanation of this discrepancy, it may be observed that the category of πρός τι encompasses, in a wider sense, the other three Plotinian categories, that is, quantity, quality and motion. This is clear in the twofold division of the categories, as shown in the above table. Therefore, it may be argued that Plotinus found it unnecessary to discuss this category at length, since he had done so with regard to the other three. However that may be, it will be worthwhile to examine very briefly how Plotinus considers each of his categories of the sensible world. In my discussion I will follow the same order as Plotinus did, so I will begin with the ''so-called" substance.
a. The Category of ούσία
Plotinus opens the discussion on the first of his categories, in which he included matter, form, and the composite, by raising the question of "What is it, then, which is the same in the three, and what will it be which makes them substance, the substance in things here below?" (VI. 3. 4, 1-2). Seeking for the "common factor" which will allow the three entities, matter, form and composite, to be regarded as one "genus," Plotinus raises the further questions:
But what is the common factor of matter and form? And how can matter be a genus, and a genus of what? For what essential differentiation is there belonging to matter? But in what genus is the product of both to be ranked? If the product of both is itself bodily substance, and each of them is not body, how could they be ranked in one and the same genus with the com posite? And how could the elements of a thing be ranked with the thing itself? But if we were to start with bodies, we should be starting with syllables. But why should we not say analogously, even if the division is not on the same lines, that instead of being in the intelligible there is matter here below, and instead of the intelligible movement there is form here below, a kind of life and perception of matter, and that matter not being out of itself corresponds to rest, and that there are sameness and otherness, since there is plenty of otherness, or rather unlikeness, here below? (VI. 3. 2, 9-22)
Resort to analogy, then, which would mean to conceive matter and form as analogous to the genera of the true Being, Substance and Motion respectively, is excluded for reasons given in the rest of VI. 3. 2. Instead, Plotinus goes on to consider five alternatives of "the common factor" or "common element," some of which resemble Aristotle's characteristics of substance.
According to the first alternative, the common element is identified as έ'δρα or ύποβάθρα (i.e. that which has the capability to serve as base). This, Plotinus remarks, may be true with regard to matter or the com posite. But apparently it cannot apply to form which, on this ground, would not be allowed to be considered as substance. So the first candidate must be eliminated.
According to the second alternative, the common element is identified as "not belonging to another" (VI. 3. 4, 7-8).25 This is evidently true
in cases of composite substances, such as Socrates. But what about form and matter? Are they not said to be the form and matter of something else? To meet objections of this sort, Plotinus proceeds to distinguish cor rectly, it would seem, between that which is said of something else because it is a part of that thing considered as a whole, and that which
PLOTINUS' REDUCTION OF ARISTOTLE'S CATEGORIES 145
is said of something else, though they differ from each other. It is to the former where both matter and form belong. Whereas attributes, such as ' 'white" for instance, which are predicated of something distinct from itself, belong to the latter. Consider:
That then which belongs to another and is said to be of that other is not substance: substance, that is, is what belongs to that which it is, or, if it is a part, is an essential completion of a composite of its own kind: for the composite is either or both parts of itself, but in relation to the composite each part is said to belong to it in another sense: or if it is a part, it is called so in relation to something else, but by itself its natural existence is said to be in being what it is, not in belonging to another. (VI. 3. 4, 20-26) According to the third alternative the common element is identified as ύποκείμενον (substrate). Plotinus thinks that this property is common to all three entities, viz. matter, form and composite, but not without some qualifications. For example, he contends that matter is said to be substrate to form in a sense which is not the same as when the composite is said to be substrate to accidents, activities, consequents etc. {Ibid. 34-35).
According to the fourth alternative the common element is identified as "not being in a substrate." Plotinus observes that this characteristic cannot be applied to all entities called substances, unless that which is in the substrate is not there "as a part of that in which it is" (VI. 3. 5, 8-10). Thus, form will not be present in matter as "in a substrate," nor will man or humanity be present in Socrates. For, as Plotinus explains, humanity, unlike boldness and whiteness, is a "part of Socrates" {Ibid. Line 13).26
It may be recalled here that Aristotle did not, in the end, admit this characteristic as the ϊδιον ούσίας on the ground that it did not characterize substances solely. For it is applicable to differentiae as well. Plotinus seems to reject the view that differentiae are μή έν ύποκειμένω. To support this thesis he argues along the following lines:
But if someone says that not being in a substrate is not a peculiarity of substance, for the essential differentiation is not itself one of the things in a substance, it is by understanding [the differentiation] as "the two-footed" that he makes this assertion that it is not in a substrate: since, if he did not understand "the two-footed," which is a particular kind of substance, but "two-footedness," not meaning a substance but a quality, then the two- footed will be in a substrate. {Ibid. 23-29)
26 "Man is part of Socrates" not in the same sense as his hand or head is part of him,
but in the sense that Socrates is an entity composite of matter and form, Platonically speaking, the Form of man.
According to the fifth and last alternative, the common element is iden tified as being "neither in a substrate nor predicated of a substrate"
{Ibid. 14-15). The ''neither/nor," it may be recalled, was supposed to
point to the peculiar characteristic of primary substance in Aristotle's text.27 As it is stated, however, this formula can apply only to the com
posite. In order to make it fit all other entities, which Plotinus calls substances, he had to modify the formula a little by adding "as of some thing else" {Ibid. Line 15). This slight modification is very important because it allows Plotinus to draw the fundamental distinction between predicates predicated of a subject from which they differ essentially (e. g. "a piece of wood is white") and predicates predicated of a subject from which they do not differ essentially (e.g. "Socrates is a man").
For in saying that Socrates is human, I am saying that a particular human being is human, predicating humanity of the human in Socrates, "but this is the same as calling Socrates Socrates, and again as predicating 'living being' of this particular living being." (VI. 3. 5, 17-23)
In other words, cases of essential predication seem to be reducible to cases of self-predication, that is, tautologies. For example, to predicate 'man' of an individual is the same, according to Plotinus, as to say that "a man is man" or, more emphatically, "Socrates is Socrates." But the problem of predication is very complex and cannot be considered here.28
Suffice it to state here that the formula "neither/nor" as modified by Plotinus can encompass both Aristotle's secondary substances and Plato's eternal Forms. Even so, matter is left outside. Realizing this, Plotinus gives up the effort to find a formula which will provide the needed "common element" or "common factor" and concludes in the following way:
But what is to be said about this substance here which we are discussing? It comes about that this substance can be understood in contrary ways according to one or more or all of these statements, since the statements fit both matter and form and the composite as well. (VI. 3. 5, 35-39) Although he has said much about this issue, Plotinus is aware that he has not clarified the category of substance. Thus, he is ready to attempt another approach in order to discover what that peculiar characteristic is which distinguishes substance as a "genus" from the other "genera" of becoming. Eventually he will find a solution to this problem in what I shall call the doctrine of "double dependence." I will explain what this