Commentaria in Summam contra Gentiles, Liber III

Fourthly, ¹ St. Thomas shows that man's happiness does not consist in the knowledge of God had from the quidditative knowledge of separated substances.

Concerning this, however, he does two things: first, he shows, by running through the positions of the philosophers, that man in the state of the way cannot know separated substances quidditatively; second, he explains that human happiness does not consist in the knowledge of separated substances such as those philosophers posited, in chapter 44.

Concerning the first, he does two things: first, he sets forth the purpose; second, he executes what was proposed, in this very chapter.²

I. As to the first, he notes first, from what was shown above in the second book, that separated substances, from the fact that God is their cause, by knowing their own essence, which is a certain likeness of God, know God himself after the manner of a kind of vision: because that thing is known by the intellect after the manner of vision whose likeness exists in the intellect, as is evident from bodily sight.

He notes secondly, as following from the preceding, that whatever intellect apprehends a separated substance quidditatively sees God in a higher way than he is known by any of the aforesaid knowledges: that is, than by the common knowledge of him which is present to all; and by demonstrative knowledge; and by knowledge through faith.

He notes thirdly that, because some have posited that man's ultimate happiness is in this life through knowing separated substances, it must be considered whether man in this life can arrive at knowing separated substances from phantasms, which is the mode proper to him in this life. For if he can do this, it will be possible for someone in this life to understand separated substances; and consequently, by seeing them, he will participate in that mode of cognition by which a separated substance, understanding itself, understands God. But if that is not possible, it will not be possible for man in the state of the way to attain the aforesaid mode of divine cognition.

2. Concerning the first statement, it must be considered that a thing is said to be seen by the intellect in two ways. For sometimes it is the same as its essence being known perfectly as it is in itself. But at other times, as it is distinguished against being known through the report of another and through hearing: and in this way, to be known through a likeness of itself existing in the intellect is to be seen. When therefore it is said here that a separated substance, by knowing itself, knows God after the manner of vision, he does not take vision in the first way, because, as he shows elsewhere,³ a created substance cannot by natural cognition see the divine essence as it is in itself; but he takes vision in the second way, namely, such that knowing God after the manner of vision is distinguished against knowing him through faith, which is to know through hearing, of which mode it was treated in the preceding chapter.

3. Concerning the second and third statements, it should be noted that, just as one who sees something in which another thing is represented also sees the thing represented, although he sees it in another, not in itself—as one who sees a mirror sees the things that are represented in the mirror—so one who knows by the intellect perfectly some essence which is a natural likeness of another intelligible object also knows the things that are represented through such an essence, while using that essence both as a thing known and as a principle of knowing; just as, because the divine essence is a representative likeness of all creatures, God therefore, by gazing upon his own essence, gazes upon all other things. Because, therefore, the essence of a separated substance is a certain likeness of God, through the inspection of which that separated substance knows God by natural cognition, therefore, if the human intellect in the way arrives at knowing the very essence of a separated substance perfectly, it will also know God himself, naturally represented through the essence of the separated substance.

On that account, in the second statement St. Thomas says that whatever intellect apprehends a separated substance by knowing what it is concerning it sees God in a higher way than he is known by faith and demonstration: namely, because to know him according as he is represented through the essence of a separated substance to the intellect of the knower is to know him more highly than through sensible creatures and through hearing from others.

In the third statement he also says that our intellect, by seeing separated substances, will participate in that mode of cognition by which a separated substance, understanding itself, understands God: namely, because just as from the fact that a separated substance, understanding its own essence, also uses it as a principle of understanding God, of whom it is a participated likeness, so also our intellect, understanding the essence of a separated substance, will understand God through that essence known; and thus there will be a similar mode of cognition on the part of the medium of knowing in which God will be known.

II. As to the second, ⁴ St. Thomas shows that our intellect cannot know the quiddities of separated substances from phantasms.

Concerning this, however, he does three things: first, he shows that it cannot know them in the way that Avempace posited; second, that it cannot do so in the way that Alexander posited, in the following chapter; third, that it cannot do so in the way that Averroes posited, in chapter 43.

Concerning the first, he does two things: first, he sets down the position of Avempace; second, he disproves it.⁵

Avempace therefore posited that through the study of the speculative sciences, from those intelligible objects which we know through phantasms, we can arrive at understanding separated substances. Furthermore, he explains this in two ways. First: through the possible intellect, which is naturally suited to know any quiddity insofar as it is a quiddity, since its proper object is what something is, we can abstract the quiddity of anything having a quiddity that is not its own quiddity. And thus, since there is no proceeding to infinity, one will successively arrive, by the way of resolution, at knowing the quiddity of a substance that does not have another quiddity, such as is the quiddity of a separated substance. This way, as the Commentator says in III De Anima, comment 36,⁶ Avempace touched upon in the Letter Which He Called the Conjunction of the Intellect.

Secondly, he explains the same thing in the book De Anima:⁷ because our intellect is naturally suited to understand a quiddity whose understood object is the same among all. But such is the quiddity of a separated substance. — The assumption is explained: because, since the understood object of one thing in me and in you is multiplied solely through the multiplication of spiritual species, it is necessary that an understood object which is not sustained in a species of this kind be the same in me and in you. But the quiddity of an understood object which our intellect is naturally suited to abstract, since it is not the quiddity of an individual—from the fact that the understood object, insofar as it is such, is universal—does not have any spiritual and individual species.

2. Note concerning the second way of this position that by spiritual forms, according to which Avempace says that understood objects are diversified, he understands not intelligible species, but imaginable species and forms, as St. Thomas expounds in IV Sent., d. 49, q. 2, a. 1. For just as the nature of a species is not diversified except as it is conjoined to individuating principles, so, says Avempace, an understood form is not diversified except according as it is conjoined to diverse imaginable forms, which namely are individual and represent the conditions of an individual.

Both of these ways agree in this foundation: that because our intellect can abstract the quiddities of material things, it can therefore also know separated quiddities. On account of this, St. Thomas said that the second way is similar to the first.

III. St. Thomas argues that this foundation, which was also that of Themistius,⁸ is frivolous, along with the position of Avempace itself.

First, thus: the universal quiddity, namely of the genus or species of these sensible things, which is the quiddity of an understood object whose intellective cognition we receive through phantasms, comprehends in itself matter and form. Therefore it is entirely dissimilar to the quiddity of a separated substance, which is simple and immaterial. Therefore, through the fact that the quiddity of a sensible thing is understood through phantasms, the quiddity of a separated substance cannot be understood.

It should be noted that, although through that which is entirely dissimilar to another according to its proper difference one can arrive at some sort of knowledge of it, insofar as they agree in something common, or insofar as one is the effect of the other, just as through the knowledge of creatures we arrive at the knowledge of God; we cannot nonetheless through it arrive at such a knowledge of it as is the knowledge by which the quiddity itself is seen as it is in itself; since everything that is known through another is known either through a likeness or in some way through a contrary. Therefore St. Thomas argues very well, from the fact that there is an all-out dissimilarity between a material quiddity and an immaterial quiddity, that an immaterial quiddity cannot be known through the knowledge of a material quiddity.

IV. Secondly, and it is a confirmation of the preceding: the quiddity of the genus or species of sensible things cannot be separated according to esse from this individual nature, unless perhaps, setting Aristotle aside, we wish to follow Plato. Therefore it is entirely dissimilar to separated substances. Therefore, etc. — The first consequence is proved: because a form that according to itself⁹ cannot be separated from some subject is not of the same ratio as that which is separated according to esse, although each is taken according to consideration without such a subject; just as magnitude and a separated substance do not have the same ratio.

V. Thirdly: if quiddities of this kind are posited to be of the same ratio, this will only be with respect to the ratio of quiddity insofar as it is quiddity, since they cannot be of the same ratio according to species, unless perhaps we follow the Platonists who posit that the species of these sensible things are the separated substances themselves. Therefore through sensible quiddities nothing will be able to be understood concerning separated substances except their remote genus. Therefore, etc. — The first consequence is proved: because the ratio of quiddity is a common ratio, namely of the genus and species of substance.¹⁰ — The second is also proved: because, when the genus is known, the species is not on that account known except in potency.

For the clarity of this argument, it must be considered that quiddity is called the essence of a thing according as it is signified through a definition. Essence, however, properly and completely belongs to substances, just as substance alone is completely and properly defined and has esse. Therefore St. Thomas says of quiddity that its ratio is common to the genus and species of substance: because namely both the genus and the species of substance are certain quiddities according as they are signified in the abstract, and substances alone properly and perfectly have a quiddity, just as they also have a definition. — Another reading has the genus¹¹ both of the species and of substance. And then the sense would be that it is common to every genus, every species, and every substance, namely a complete one. — From this, therefore, that the ratio of quiddity is common to the genus and species of substance, it is held that it is, as it were, the remote genus of any separated substance: whether by the name genus we understand that which is properly a genus, namely substance, which is the most general genus, which is common both to all genera and to all species contained under it;

VI. Fourthly: to understand the quiddity of one sensible thing is not sufficient for understanding the quiddity of another sensible thing; for one born blind, through the fact that he understands the quiddity of sound, does not understand the quiddity of color. Therefore, etc. — The consequence is proved: because greater is the distance of a separated substance from sensible things than that of one sensible thing from another.

Fifthly: if we posit that separated substances cause the forms of sensible things from the movements of the spheres, this mode is not sufficient for the purpose. And it is argued thus: neither by reason of the likeness of sensible things to separated substances, nor by reason of demonstrated power, can the quiddity of a separated substance be known from a sensible quiddity. Therefore, etc.

The antecedent is proved. For the first part, indeed, because sensible things are not of the same species with separated substances. — For the second part, however, because no sensible effect equals the power of a separated substance, since the powers of separated substances exceed all sensible effects that we comprehend by the intellect, just as a universal power exceeds a particular effect. — The consequence is also shown: because a cause is not known through an effect except either by reason of a likeness between cause and effect, or insofar as the effect demonstrates the power of the cause. — Concerning the subject matter of this argument, it was determined in the preceding sections.¹²

VII. Sixthly: through none of the speculative sciences does it happen that one knows of any of the separated substances what it is, since none teaches this, but only that they are. Therefore, etc. — The consequence is proved: because all intelligible objects to whose knowledge we arrive through inquiry and study belong to some one of the speculative sciences.

If it should be said that it is possible for there to be some such speculative science, although it has not yet been discovered, this is nothing. Because sensible things do not sufficiently lead us into the knowledge of immaterial things, as has been shown. Furthermore, all the principles of any science whatsoever depend on first indemonstrable per se known principles, the knowledge of which we receive from sensible things.

2. For the clarity of this argument, it must be considered, from the teaching of St. Thomas on Boethius's De Trinitate, the last article,¹³ that since, both in demonstrations and in the discoveries of definitions, in the speculative sciences one always proceeds from something previously known, and there is no process to infinity in a resolution of this kind, it is necessary to arrive at some first things known per se, both in propositions and in concepts; as are the first indemonstrable propositions, and the concept of being, which is best known to all, and similarly the concept of the one, and other such things. Hence it happens that only those things can be known in the sciences by way of demonstration or definition to which these naturally known things themselves can extend, which are the first principles of our cognition, just as a particular cause can only produce things contained under a universal cause. But these things are known to us by the natural light of the agent intellect. By which light indeed nothing is made manifest to man except insofar as phantasms are made through it actually intelligible. Phantasms, however, are received from sense. Therefore these naturally known principles do not extend except to those things whose knowledge we can receive from those things which we perceive by sense.

On that account St. Thomas very well deduces, from the fact that through sensible quiddities we cannot know immaterial quiddities, that there can be no human speculative science that leads us into the knowledge of quiddities of this kind, since all sciences proceed from such naturally known principles.

VIII. From these arguments St. Thomas leaves the solution of the arguments of Avempace as manifest. For it is clear that both consequences are false: namely this one, 'Our intellect can abstract a quiddity, therefore it can know a quiddity abstracted per se'; similarly also this one, 'Our intellect is naturally suited to understand a quiddity whose understood object is one among all, therefore also an immaterial and separated quiddity.'

If anyone should say, however, that Avempace does not bring forward those arguments as demonstrative simpliciter, but as showing from a sign—for from the fact that we see the intellect understand an abstracted quiddity, and abstract it even if it were abstractable to infinity, it is a sign to us that it can also understand quiddities abstracted through themselves—it is answered that that is not a sufficient sign. Because however many quiddities our intellect can abstract, all those quiddities abstracted through it are in some way of the same ratio, insofar as they are all quiddities of material things. A quiddity separated of itself, however, is not of the same ratio with quiddities abstracted through the intellect, since it is entirely outside the genus of material things. Therefore it is not similar.