Part I (Prima Pars) Part 121 (1/2)
Obj. 3: Further, the likeness of the agent is received into the patient according to the nature of the patient. But the pa.s.sive intellect is an immaterial power. Therefore its immaterial nature suffices for forms to be received into it immaterially. Now a form is intelligible in act from the very fact that it is immaterial.
Therefore there is no need for an active intellect to make the species actually intelligible.
_On the contrary,_ The Philosopher says (De Anima iii, 5), ”As in every nature, so in the soul is there something by which it becomes all things, and something by which it makes all things.” Therefore we must admit an active intellect.
_I answer that,_ According to the opinion of Plato, there is no need for an active intellect in order to make things actually intelligible; but perhaps in order to provide intellectual light to the intellect, as will be explained farther on (A. 4). For Plato supposed that the forms of natural things subsisted apart from matter, and consequently that they are intelligible: since a thing is actually intelligible from the very fact that it is immaterial. And he called such forms ”species or ideas”; from a partic.i.p.ation of which, he said that even corporeal matter was formed, in order that individuals might be naturally established in their proper genera and species: and that our intellect was formed by such partic.i.p.ation in order to have knowledge of the genera and species of things. But since Aristotle did not allow that forms of natural things exist apart from matter, and as forms existing in matter are not actually intelligible; it follows that the natures or forms of the sensible things which we understand are not actually intelligible. Now nothing is reduced from potentiality to act except by something in act; as the senses as made actual by what is actually sensible. We must therefore a.s.sign on the part of the intellect some power to make things actually intelligible, by abstraction of the species from material conditions. And such is the necessity for an active intellect.
Reply Obj. 1: Sensible things are found in act outside the soul; and hence there is no need for an active sense. Wherefore it is clear that in the nutritive part all the powers are active, whereas in the sensitive part all are pa.s.sive: but in the intellectual part, there is something active and something pa.s.sive.
Reply Obj. 2: There are two opinions as to the effect of light. For some say that light is required for sight, in order to make colors actually visible. And according to this the active intellect is required for understanding, in like manner and for the same reason as light is required for seeing. But in the opinion of others, light is required for sight; not for the colors to become actually visible; but in order that the medium may become actually luminous, as the Commentator says on _De Anima_ ii. And according to this, Aristotle's comparison of the active intellect to light is verified in this, that as it is required for understanding, so is light required for seeing; but not for the same reason.
Reply Obj. 3: If the agent pre-exist, it may well happen that its likeness is received variously into various things, on account of their dispositions. But if the agent does not pre-exist, the disposition of the recipient has nothing to do with the matter. Now the intelligible in act is not something existing in nature; if we consider the nature of things sensible, which do not subsist apart from matter. And therefore in order to understand them, the immaterial nature of the pa.s.sive intellect would not suffice but for the presence of the active intellect which makes things actually intelligible by way of abstraction.
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FOURTH ARTICLE [I, Q. 79, Art. 4]
Whether the Active Intellect Is Something in the Soul?
Objection 1: It would seem that the active intellect is not something in the soul. For the effect of the active intellect is to give light for the purpose of understanding. But this is done by something higher than the soul: according to John 1:9, ”He was the true light that enlighteneth every man coming into this world.” Therefore the active intellect is not something in the soul.
Obj. 2: Further, the Philosopher (De Anima iii, 5) says of the active intellect, ”that it does not sometimes understand and sometimes not understand.” But our soul does not always understand: sometimes it understands, sometimes it does not understand. Therefore the active intellect is not something in our soul.
Obj. 3: Further, agent and patient suffice for action. If, therefore, the pa.s.sive intellect, which is a pa.s.sive power, is something belonging to the soul; and also the active intellect, which is an active power: it follows that a man would always be able to understand when he wished, which is clearly false. Therefore the active intellect is not something in our soul.
Obj. 4: Further, the Philosopher (De Anima iii, 5) says that the active intellect is a ”substance in actual being.” But nothing can be in potentiality and in act with regard to the same thing. If, therefore, the pa.s.sive intellect, which is in potentiality to all things intelligible, is something in the soul, it seems impossible for the active intellect to be also something in our soul.
Obj. 5: Further, if the active intellect is something in the soul, it must be a power. For it is neither a pa.s.sion nor a habit; since habits and pa.s.sions are not in the nature of agents in regard to the pa.s.sivity of the soul; but rather pa.s.sion is the very action of the pa.s.sive power; while habit is something which results from acts. But every power flows from the essence of the soul. It would therefore follow that the active intellect flows from the essence of the soul.
And thus it would not be in the soul by way of partic.i.p.ation from some higher intellect: which is unfitting. Therefore the active intellect is not something in our soul.
_On the contrary,_ The Philosopher says (De Anima iii, 5), that ”it is necessary for these differences,” namely, the pa.s.sive and active intellect, ”to be in the soul.”
_I answer that,_ The active intellect, of which the Philosopher speaks, is something in the soul. In order to make this evident, we must observe that above the intellectual soul of man we must needs suppose a superior intellect, from which the soul acquires the power of understanding. For what is such by partic.i.p.ation, and what is mobile, and what is imperfect always requires the pre-existence of something essentially such, immovable and perfect. Now the human soul is called intellectual by reason of a partic.i.p.ation in intellectual power; a sign of which is that it is not wholly intellectual but only in part. Moreover it reaches to the understanding of truth by arguing, with a certain amount of reasoning and movement. Again it has an imperfect understanding; both because it does not understand everything, and because, in those things which it does understand, it pa.s.ses from potentiality to act. Therefore there must needs be some higher intellect, by which the soul is helped to understand.
Wherefore some held that this intellect, substantially separate, is the active intellect, which by lighting up the phantasms as it were, makes them to be actually intelligible. But, even supposing the existence of such a separate active intellect, it would still be necessary to a.s.sign to the human soul some power partic.i.p.ating in that superior intellect, by which power the human soul makes things actually intelligible. Just as in other perfect natural things, besides the universal active causes, each one is endowed with its proper powers derived from those universal causes: for the sun alone does not generate man; but in man is the power of begetting man: and in like manner with other perfect animals. Now among these lower things nothing is more perfect than the human soul. Wherefore we must say that in the soul is some power derived from a higher intellect, whereby it is able to light up the phantasms. And we know this by experience, since we perceive that we abstract universal forms from their particular conditions, which is to make them actually intelligible. Now no action belongs to anything except through some principle formally inherent therein; as we have said above of the pa.s.sive intellect (Q. 76, A. 1). Therefore the power which is the principle of this action must be something in the soul. For this reason Aristotle (De Anima iii, 5) compared the active intellect to light, which is something received into the air: while Plato compared the separate intellect impressing the soul to the sun, as Themistius says in his commentary on _De Anima_ iii. But the separate intellect, according to the teaching of our faith, is G.o.d Himself, Who is the soul's Creator, and only beat.i.tude; as will be shown later on (Q. 90, A. 3; I-II, Q. 3, A. 7). Wherefore the human soul derives its intellectual light from Him, according to Ps. 4:7, ”The light of Thy countenance, O Lord, is signed upon us.”
Reply Obj. 1: That true light enlightens as a universal cause, from which the human soul derives a particular power, as we have explained.
Reply Obj. 2: The Philosopher says those words not of the active intellect, but of the intellect in act: of which he had already said: ”Knowledge in act is the same as the thing.” Or, if we refer those words to the active intellect, then they are said because it is not owing to the active intellect that sometimes we do, and sometimes we do not understand, but to the intellect which is in potentiality.
Reply Obj. 3: If the relation of the active intellect to the pa.s.sive were that of the active object to a power, as, for instance, of the visible in act to the sight; it would follow that we could understand all things instantly, since the active intellect is that which makes all things (in act). But now the active intellect is not an object, rather is it that whereby the objects are made to be in act: for which, besides the presence of the active intellect, we require the presence of phantasms, the good disposition of the sensitive powers, and practice in this sort of operation; since through one thing understood, other things come to be understood, as from terms are made propositions, and from first principles, conclusions. From this point of view it matters not whether the active intellect is something belonging to the soul, or something separate from the soul.
Reply Obj. 4: The intellectual soul is indeed actually immaterial, but it is in potentiality to determinate species. On the contrary, phantasms are actual images of certain species, but are immaterial in potentiality. Wherefore nothing prevents one and the same soul, inasmuch as it is actually immaterial, having one power by which it makes things actually immaterial, by abstraction from the conditions of individual matter: which power is called the ”active intellect”; and another power, receptive of such species, which is called the ”pa.s.sive intellect” by reason of its being in potentiality to such species.
Reply Obj. 5: Since the essence of the soul is immaterial, created by the supreme intellect, nothing prevents that power which it derives from the supreme intellect, and whereby it abstracts from matter, flowing from the essence of the soul, in the same way as its other powers.
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FIFTH ARTICLE [I, Q. 79, Art. 5]
Whether the Active Intellect Is One in All?
Objection 1: It would seem that there is one active intellect in all.
For what is separate from the body is not multiplied according to the number of bodies. But the active intellect is ”separate,” as the Philosopher says (De Anima iii, 5). Therefore it is not multiplied in the many human bodies, but is one for all men.