This chapter is a running commentary on De anima, III, v, and may be more profitably presented by a description of its contents than by a translation.
1. On anagkê kai en tê psuchê huparchein tautas tas diaphoras (these differences must also be in the soul), St Thomas points out that the differences in question, to wit, the potential and the active intellect, are both said to be "in the soul," which excludes either of them from being a faculty extrinsic to the soul.
2. On en hapasê tê phusei, which in his translation appears as in omni natura, and which he takes to mean, not as the Greek means, "in all nature," but in every natural substance," he argues that both the hulê, or potential intellect, and the aition kai poiêtikon, or active intellect, must be in the natural substance of the soul.
3. Upon the words, used of the active intellect, that it is hôs hexis tis, hoion to phôs (as a habit, like light), he says that as a habit does not exist by itself, so neither can, on this showing, the active intellect. He adds that 'habit' here does not mean 'habitual knowledge,' as when we speak of 'a habit (i.e., habitual knowledge) of first principles,' but a positive endowment, actual and formal, as opposed to privation and potentiality.
4. Of the four epithets bestowed on the active intellect, chôristos, amigês, apathês, tê ousia ôn energeia (separate, unmingled, impassible, by essence being in act), he observes that the first and second have already been applied to the potential intellect: see Chap. IV, n. 6, ho de chôristos: IV, 3, amige einai . . . . oude memichthai tô sômati. The third, he says, has been applied to the potential intellect with a distinction (he refers to iv, 5, 6): the potential intellect is impassible, as not being acted on by matter, having no bodily organ to receive direct impressions from material things: but it receives impressions from the active intellect. The fourth, he says, has been flatly denied of the potential intellect, which is said, iv, 12, to be dunamei pôs ta noêta all' entelecheia ouden prin an noê (potentially identified with the intelligible forms, but actually nothing before it understands). He concludes that the word chôristos is only applied to the active intellect in the same sense in which it has already been referred to the potential intellect, iv, 9, to men gar aisthêtikon ouk aneu sômatos ho de chôristos (the faculty of sense is not without body, but this is separate). He identifies chôristos with aneu sômatos, as meaning 'operative without bodily organ.'
5. On to d' auto estin hê kat' energeian epistêmê tô pragmati (actual knowledge is identical with its object), -- which means that, inasmuch as objects of knowledge become present by representation in the mind, the mind in knowing anything knows itself, -- St Thomas blames Averroes for taking this to be true only of the active intellect: he cites iv, 13, to auto esti to nooun kai to nooumenon, hê gar thêoretikê epistêmê kai to outôs epistêton to auto estin (knower and known are identical, for speculative science and its object are one), where he says that Aristotle speaks, not of the active, but of the potential intellect. In the words hê kat' energeian epistêmê (scientia in acta) St Thomas discovers a tertium quid, which is neither potential nor active intellect, but a combination of the two: he calls it intellectus in actu, 'the intellect as actually understanding,' the concrete mind at work.
6. On hê de kata dunamin chronô protera en tô heni, holôs oude chronô (potential knowledge is prior in time to actual knowledge in the individual, but all the world over it is not prior even in time), he is misled by his Latin translation, qui vero secundum potentiam, as though the Greek had been ho de kata dunamin nous. He takes it for a question of priority in time between the potential intellect and the concrete, actually thinking mind (intellectus in actu). The error is not serious.
7. Coming to ouch hote men noei, hote de ou noei (it does not at one time think, and at another time not think), he says that this is spoken of the actually thinking mind, to mark it off from the potential intellect. His conclusion is: "The mind comes to be actually thinking by being identified with the objects of thought: hence it is not open to it at times to think and at times not to think." This may mean -- as undoubtedly it is Aristotle's meaning: 'There must be thinking so long as there are things: but there are always things: therefore there is always thinking.' Then the question comes: 'Yes, but whose thinking?' -- to which St Thomas gives no answer. To interpret with Silvester Maurus, 'so long as the mind is actually thinking, it thinks unceasingly,' is to father no very profound truth upon the Philosopher.
8. Upon chôristheis de esti monon touth hoper esti (when separated, it is only that which it is) St. Thomas is altogether thrown out by his Latin, separatum hoc solum quod vere est (that alone is separate which truly is), as though chôristheis (separatum) were the predicate. He takes the meaning to be that the actually thinking mind in man, inclusive at once of potential and active intellect, is 'separate' in the sense of not operating through a bodily organ. On touto monon athanaton kai aidion (this alone is mortal and everlasting), all his comment is "as being independent of the body, since it is separate." On the last sentence, ou mnêmoneuomen de k.t.l., he makes no comment whatever in this place, but see Chap. LXX, arg. 5.
No one can seriously contend that, working under such disadvantages, St Thomas has succeeded in adequately interpreting this, one of the most difficult chapters in Aristotle. I recommend the reader to study it in G. Rodier's masterly work, Aristote, Traité de l'âme, 2 vols., text, translation, and notes (Leroux, Paris, 1900). I offer these few final remarks.
(a) From aei gar to oude chronô, is a parenthesis; as Philoponus says, touto en mesô erripsen. The meaning is, as St Thomas well indicates, that though in the individual mind knowledge is first potential, then actual, yet somewhere in the range of being there is an actual knowledge prior to all potential. This is only carrying out the Aristotelian principle that ultimately the actual always precedes the potential: esti gar ex enelecheia ontos panta ta gignomena (De anima, III, vii, 1), a principle well put forward by Rodier, vol. II, p. 490. What actually thinking mind precedes all potentiality of thought, Aristotle does not tell us in this chapter.
(b) The words, all' ouch hote men noei, hote de ou noei, are to be taken in close connexion with tê ousia ôn energeia, the whole meaning: 'this mind, ever essentially active, thinks continually, and not merely at intervals.' Whether this refers to the mind of the race, Aristotle agreeing with Averroes that mankind have existed from eternity, or whether it points to some superhuman intelligence, is a question which will be debated as long as Aristotle continues to be read.
(c) chôristheis d' esti monon touth hoper esti, "when separated from the body [in death, as Rodier rightly explains], it is its proper self, and nothing else," -- pure nous, apart from phantasy and sensation and bodily organism; and this pure nous is, in some undefined way, "immortal and everlasting." In esti touth hoper esti I think we may further recognise some slight influence of a familiar idiom, by which a Greek says that a thing 'is what it is,' when he is either unable or reluctant to enter into further detail.
(d) The concluding words mean: 'We have no memory [after death, of the transactions of our earthly existence], because though the nous is unaffected by death (apathes), yet the passive intellect [ho pathêtikos nous, the cogitative faculty with the phantasy, see St Thomas, Chap. LX], is perishable [and perishes with the body], and without this there is no understanding [of things learnt in life with its concurrence, -- cf. De anima, III, viii, 5, hotan theôrê, anagkê hama phantasma ti theôrein].' This sense seems definitely fixed as the mind of Aristotle by a previous passage, De anima, I, iv, 12-15: -- "The nous within us seems to be a subsistent being (ousia) and imperishable. If it could be impaired, it would be impaired most in the feebleness of old age: whereas, we may say, the case is the same with intellect as with sense: for if the old man got a young man's eye, he would see as the young man does. So old age is not an affection of the soul, but an affection of what contains the soul, as in drunken bouts and illnesses. Thus the intellectual and speculative faculty decays when something else in the man decays, but of itself it is imperishable (apathes). But the exercise of the cogitative faculty (to dianoeisthai), and the passions of love and hate, are not functions of nous, but of this individual organism that contains nous, as containing it. Therefore when this organism perishes in death, the soul neither remembers nor loves: for memory and [the passion of] love were not affections of the intelligent soul, but of the compound organism wherein soul and matter met, which has not perished: but nous perhaps is something more divine and imperishable (ho de nous isôs theioteron ti kai apathes estin).
Of God and His Creatures: 2.78