Summa Theologica Part I (Prima Pars) Part 121

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.

Obj. 2: Further, the active intellect is the cause of the universal, which is one in many. But that which is the cause of unity is still more itself one. Therefore the active intellect is the same in all.

Obj. 3: Further, all men agree in the first intellectual concepts.

But to these they a.s.sent by the active intellect. Therefore all agree in one active intellect.

_On the contrary,_ The Philosopher says (De Anima iii, 5) that the active intellect is as a light. But light is not the same in the various things enlightened. Therefore the same active intellect is not in various men.

_I answer that,_ The truth about this question depends on what we have already said (A. 4). For if the active intellect were not something belonging to the soul, but were some separate substance, there would be one active intellect for all men. And this is what they mean who hold that there is one active intellect for all. But if the active intellect is something belonging to the soul, as one of its powers, we are bound to say that there are as many active intellects as there are souls, which are multiplied according to the number of men, as we have said above (Q. 76, A. 2). For it is impossible that one same power belong to various substances.

Reply Obj. 1: The Philosopher proves that the active intellect is separate, by the fact that the pa.s.sive intellect is separate: because, as he says (De Anima iii, 5), "the agent is more n.o.ble than the patient." Now the pa.s.sive intellect is said to be separate, because it is not the act of any corporeal organ. And in the same sense the active intellect is also called "separate"; but not as a separate substance.

Reply Obj. 2: The active intellect is the cause of the universal, by abstracting it from matter. But for this purpose it need not be the same intellect in all intelligent beings; but it must be one in its relationship to all those things from which it abstracts the universal, with respect to which things the universal is one. And this befits the active intellect inasmuch as it is immaterial.

Reply Obj. 3: All things which are of one species enjoy in common the action which accompanies the nature of the species, and consequently the power which is the principle of such action; but not so as that power be identical in all. Now to know the first intelligible principles is the action belonging to the human species. Wherefore all men enjoy in common the power which is the principle of this action: and this power is the active intellect. But there is no need for it to be identical in all. Yet it must be derived by all from one principle. And thus the possession by all men in common of the first principles proves the unity of the separate intellect, which Plato compares to the sun; but not the unity of the active intellect, which Aristotle compares to light.

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SIXTH ARTICLE [I, Q. 79, Art. 6]

Whether Memory Is in the Intellectual Part of the Soul?

Objection 1: It would seem that memory is not in the intellectual part of the soul. For Augustine says (De Trin. xii, 2,3,8) that to the higher part of the soul belongs those things which are not "common to man and beast." But memory is common to man and beast, for he says (De Trin. xii, 2, 3, 8) that "beasts can sense corporeal things through the senses of the body, and commit them to memory."

Therefore memory does not belong to the intellectual part of the soul.

Obj. 2: Further, memory is of the past. But the past is said of something with regard to a fixed time. Memory, therefore, knows a thing under a condition of a fixed time; which involves knowledge under the conditions of "here" and "now." But this is not the province of the intellect, but of the sense. Therefore memory is not in the intellectual part, but only in the sensitive.

Obj. 3: Further, in the memory are preserved the species of those things of which we are not actually thinking. But this cannot happen in the intellect, because the intellect is reduced to act by the fact that the intelligible species are received into it. Now the intellect in act implies understanding in act; and therefore the intellect actually understands all things of which it has the species.

Therefore the memory is not in the intellectual part.

_On the contrary,_ Augustine says (De Trin. x, 11) that "memory, understanding, and will are one mind."

_I answer that,_ Since it is of the nature of the memory to preserve the species of those things which are not actually apprehended, we must first of all consider whether the intelligible species can thus be preserved in the intellect: because Avicenna held that this was impossible. For he admitted that this could happen in the sensitive part, as to some powers, inasmuch as they are acts of corporeal organs, in which certain species may be preserved apart from actual apprehension. But in the intellect, which has no corporeal organ, nothing but what is intelligible exists. Wherefore every thing of which the likeness exists in the intellect must be actually understood. Thus, therefore, according to him, as soon as we cease to understand something actually, the species of that thing ceases to be in our intellect, and if we wish to understand that thing anew, we must turn to the active intellect, which he held to be a separate substance, in order that the intelligible species may thence flow again into our pa.s.sive intellect. And from the practice and habit of turning to the active intellect there is formed, according to him, a certain apt.i.tude in the pa.s.sive intellect for turning to the active intellect; which apt.i.tude he calls the habit of knowledge. According, therefore, to this supposition, nothing is preserved in the intellectual part that is not actually understood: wherefore it would not be possible to admit memory in the intellectual part.

But this opinion is clearly opposed to the teaching of Aristotle.

For he says (De Anima iii, 4) that, when the pa.s.sive intellect "is identified with each thing as knowing it, it is said to be in act,"

and that "this happens when it can operate of itself. And, even then, it is in potentiality, but not in the same way as before learning and discovering." Now, the pa.s.sive intellect is said to be each thing, inasmuch as it receives the intelligible species of each thing. To the fact, therefore, that it receives the species of intelligible things it owes its being able to operate when it wills, but not so that it be always operating: for even then is it in potentiality in a certain sense, though otherwise than before the act of understanding--namely, in the sense that whoever has habitual knowledge is in potentiality to actual consideration.

The foregoing opinion is also opposed to reason. For what is received into something is received according to the conditions of the recipient. But the intellect is of a more stable nature, and is more immovable than corporeal nature. If, therefore, corporeal matter holds the forms which it receives, not only while it actually does something through them, but also after ceasing to act through them, much more cogent reason is there for the intellect to receive the species unchangeably and lastingly, whether it receive them from things sensible, or derive them from some superior intellect. Thus, therefore, if we take memory only for the power of retaining species, we must say that it is in the intellectual part. But if in the notion of memory we include its object as something past, then the memory is not in the intellectual, but only in the sensitive part, which apprehends individual things. For past, as past, since it signifies being under a condition of fixed time, is something individual.

Reply Obj. 1: Memory, if considered as retentive of species, is not common to us and other animals. For species are not retained in the sensitive part of the soul only, but rather in the body and soul united: since the memorative power is the act of some organ. But the intellect in itself is retentive of species, without the a.s.sociation of any corporeal organ. Wherefore the Philosopher says (De Anima iii, 4) that "the soul is the seat of the species, not the whole soul, but the intellect."

Reply Obj. 2: The condition of past may be referred to two things--namely, to the object which is known, and to the act of knowledge. These two are found together in the sensitive part, which apprehends something from the fact of its being immuted by a present sensible: wherefore at the same time an animal remembers to have sensed before in the past, and to have sensed some past sensible thing. But as concerns the intellectual part, the past is accidental, and is not in itself a part of the object of the intellect. For the intellect understands man, as man: and to man, as man, it is accidental that he exist in the present, past, or future. But on the part of the act, the condition of past, even as such, may be understood to be in the intellect, as well as in the senses. Because our soul's act of understanding is an individual act, existing in this or that time, inasmuch as a man is said to understand now, or yesterday, or tomorrow. And this is not incompatible with the intellectual nature: for such an act of understanding, though something individual, is yet an immaterial act, as we have said above of the intellect (Q. 76, A. 1); and therefore, as the intellect understands itself, though it be itself an individual intellect, so also it understands its act of understanding, which is an individual act, in the past, present, or future. In this way, then, the notion of memory, in as far as it regards past events, is preserved in the intellect, forasmuch as it understands that it previously understood: but not in the sense that it understands the past as something "here"

and "now."

Reply Obj. 3: The intelligible species is sometimes in the intellect only in potentiality, and then the intellect is said to be in potentiality. Sometimes the intelligible species is in the intellect as regards the ultimate completion of the act, and then it understands in act. And sometimes the intelligible species is in a middle state, between potentiality and act: and then we have habitual knowledge. In this way the intellect retains the species, even when it does not understand in act.

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