LECTIO TEN

             § 728. Having examined the potential intellect, the Philosopher now turns his attention to the agent intellect. He first shows by argument and illustration that there is such a thing as the agent intellect; and then, at 'And this is intellect', he explains its nature. The argument he uses is this. In any nature which alternates between potency and actuality we must posit (1) a factor akin to the matter which, in any given class of things, is potentially all the particulars included in the class; and (2) another factor which operates as an active and productive cause, like art with respect to its material. Since then the intellectual part of the soul alternates between potency and act, it must include these two distinct principles: first, a potentiality within which all intelligible concepts can be actualised (this is the potential intellect already discussed); and then, also, a principle whose function it is to actualise those concepts. And this latter is the agent intellect,--being 'a sort of state'.

             § 729. This last phrase has led some to suppose that the agent intellect is one with the 'intellect' which is a habitual apprehension of first principles. But it is not so; for the latter 'intellect' presupposes the actual presence in the mind of certain intelligible and understood objects, which are the terms in understanding which we apprehend the truth of first principles. So the view in question would imply that the agent intellect was not, as Aristotle here maintains, the primary source, for us, of the actual intelligibility of anything. Therefore I hold that the term 'state' is used here in the sense in which Aristotle often calls any form or nature a 'state', to distinguish it from a privation or a potency. In this case the agent intellect is called a state to distinguish it from the intellect in potency.

             § 730. So he calls it a state, and compares it to light which 'in a way' brings colours from potency to act;--'in a way' because, as we have seen, colour is visible of itself; all that light does is to actualise a transparent medium which can then be modified by colour so that colour is seen. The agent intellect, on the other hand, actualises the intelligible notions themselves, abstracting them from matter, i.e. bringing them from potential to actual intelligibility.

             § 731. The reason why Aristotle came to postulate an agent intellect was his rejection of Plato's theory that the essences of sensible things existed apart from matter, in a state of actual intelligibility. For Plato there was clearly no need to posit an agent intellect. But Aristotle, who regarded the essences of sensible things as existing in matter with only a potential intelligibility, had to invoke some abstractive principle in the mind itself to render these essences actually intelligible.

             § 732. Next, at 'And this etc.', he states four qualities or conditions of the agent intellect: first, its separation from matter; second, its impassibility; third, its purity, by which he means that it is neither made up of bodily natures nor conjoined with a bodily organ. Now these three qualities are also found in the potential intellect; but the fourth is proper to the agent intellect, and consists in its being essentially in act; whereas the potential intellect is essentially potential and comes to act only by receiving an intelligible object.

             § 733. To demonstrate these qualities he argues as follows. What acts is nobler than what is acted on, an active principle is nobler than its material. Now the agent intellect, as we have said, is to the potential intellect as an active principle to its material; therefore it is the nobler of the two. If, then, the potential intellect be (as has been shown) free from matter and impassible and pure, a fortiori the agent intellect. Consequently the agent intellect is also essentially actual, for only in virtue of its actuality is an active principle nobler than a passive one.

             § 734. Now what is said here has led some to conceive of the agent intellect as a separated substance, subsisting apart from the potential intellect. But this does not seem to be true; for human nature would be a deficient nature if it lacked any one of the principles that it needs for its naturally appropriate activity of understanding; and this requires both the potential and the agent intellects. Hence, complete human nature requires that both of these be intrinsic to man. Moreover, just as the potential intellect's function of receiving intelligible objects is attributed to the individual man as its subject, so also is the work of the agent intellect, the abstracting of such objects from matter. And this is only possible in so far as the formal principle of the latter activity is one in being with the individual man.

             § 735. Nor is it enough to say that the intelligible notions formed by the agent intellect subsist somehow in phantasms, which are certainly intrinsic to us; for as we have already observed in treating of the potential intellect, objects only become actually intelligible when abstracted from phantasms; so that, merely by way of the phantasms, we cannot attribute the work of the agent intellect to ourselves. Besides, the agent intellect is to ideas in act in the mind as art is to the ideas it works by; and obviously the things on which art impresses such ideas do not themselves produce the art; hence, even granted that we were the subjects of ideas made actually intelligible in us, it would not follow that it is we who produce them by means of an agent intellect in ourselves.

             § 736. Nor does the above theory agree with Aristotle who expressly states that these two distinct powers, the agent and the potential intellects, are in the soul; thus making it quite clear that he takes them to be parts or potencies of the soul, not distinct substances.

             § 737. The chief difficulty arises from the fact that, while the potential intellect is in potency to intelligible objects, the agent intellect stands to the latter as a being already in act. And it would seem impossible that one and the same thing should be at once in act and in potency to the same object; and therefore that these two intellects should belong to the one substance of the soul.

             § 738. But there is really no difficulty in this if we understand aright how the potential intellect is potential with respect to intelligible objects, and how the latter are potential with respect to the agent intellect. In the former case the potentiality is that of the indefinite to the definite; for the potential intellect is not, as such, endowed with any definite and particular sensible thing's nature. Yet only definite particular natures are, as such, intelligible--hence Aristotle's earlier comparison of the intellectual power's relation to intelligible objects with that of a sheet of paper to particular definite pictures. And from this point of view the agent intellect is not in act.

             § 739. For if the agent intellect as such included the definite forms of all intelligible objects, the potential intellect would not depend upon phantasms; it would be actualised simply and solely by the agent intellect; and the latter's relation to intelligible objects would not be that of a maker to something made, as the Philosopher here says; for it would simply be identical with them. What makes it therefore in act with respect to intelligible objects is the fact that it is an active immaterial force able to assimilate other things to itself, i.e. to immaterialise them. In this way it renders the potentially intelligible actually so (like light which, without containing particular colours, actually brings colours into act). And because this active force is a certain participation in the intellectual light of separated substances, the Philosopher compares it to a state and to light; which would not be an appropriate way of describing it if it were itself a separate substance.

             § 740. Next, at 'Knowledge in act', he states his conclusions concerning intellect as in act; and first he states its properties; and then, at 'Only separated', how the intellectual part of the soul in general differs from the rest of the soul. Regarding the former point, he states three properties of intellect in act. First, its actual knowledge is identical with the thing known; which is not true of intellect as potential. Secondly, though in one and the same thing potential knowledge is prior in time to actual knowledge, yet, speaking universally, potential knowledge is not prior either in nature or in time. In Book IX of the Metaphysics Aristotle had said that act is by nature prior to potency, but not in time in one and the same thing; for a thing is first in potency and afterwards in act. But universally speaking act takes priority even in time; because no potency would ever be actualised unless something were already in act. So, even in the case of potential knowledge, no one ever comes to know anything actually, whether through his own effort or another's teaching, except in virtue of some pre-existing actual knowledge, as it is said in Book I of the Posterior Analytics.

             § 741. The third property of intellect as in act, differentiating it from the potential intellect and from intellect in habitual possession of knowledge, is that it is always in act; for it simply is the act of understanding. In the other cases intellect is sometimes in act and sometimes in potency.

             § 742. Next, at 'Only separated', he states the properties of the intellect as a whole; first stating the truth, and then refuting an objection. He says, then, that only the mind separated from matter is that which really is mind; and he speaks here, not of the agent or passive intellect in isolation, but of both together, since both have been described as separated from matter. And the whole intellect is so described because it operates without a bodily organ.

             § 743. And in line with what he said at the beginning of this book, that the soul might be separable from the body if any of its activities were proper to itself, he now concludes that the soul's intellectual part alone is immortal and perpetual. This is what he has said in Book II, namely that this 'kind' of soul was separable from others as the perpetual from the mortal, -perpetual in the sense that it survives for ever, not in the sense that it always has existed; for as he shows in Book XII of the Metaphysics, forms cannot exist before their matter. The soul, then (not all of it, but only its intellectual part) will survive its matter.

             § 744. Next, at 'It does not remember', he meets an objection. For we might suppose that knowledge would remain unchanged in the intellectual part of the soul which survives. But already in Book I he has disallowed this, where he observed that the act of the intellect must cease when something else dies; and that after death the soul remembers and loves no more.

             § 745. So now he adds that what we have known in life is not recalled after death; because 'it is impassible', i.e. that part of the intellectual soul of which he speaks; which, therefore, is unaffected by passions such as love and hatred and reminiscence and so forth, which all depend on modifications of the body. For the 'passive intellect'--a part of the soul which depends on the aforesaid passions--is certainly mortal; for it belongs to our sensitive nature. Nevertheless, it is called 'intellect' and 'rational' because it has a certain share in reason: it obeys and is governed by reason (see Book I of the Ethics). And without the co-operation of this embodied part of the soul there is no understanding anything; for the intellect always requires phantasms, as we shall see. Hence, after the body's death the soul no longer knows anything in the same way as before. But how it does know anything then is not part of our present enquiry.

430a 26-431b 4