Skip to content

Category: SAMT

A tour through Saint Thomas Aquinas’s Summa Contra Gentiles.

August 19, 2018 | No comments

Summary Against Modern Thought: Ultimate Happiness Does Come In Knowing Separate Substances

Previous post.

We’re closing in on ultimate happiness! You didn’t think it would be easy, did you? A short chapter this week. But an important one. See paragraph 3 for a huge limitation of science!

THAT MAN’S ULTIMATE FELICITY DOES NOT CONSIST IN THE KIND OF KNOWLEDGE OF SEPARATE SUBSTANCES THAT THE FOREGOING OPINIONS ASSUME

1 Of course, it is not possible to identify human felicity with such knowledge of separate substances, as the aforementioned philosophers have maintained.

2 Indeed, a thing is futile which exists for an end which it cannot attain. So, since the end of man is felicity, to which his natural desire tends, it is not possible for the felicity of man to be placed in something that man cannot achieve. Otherwise, it would follow that man is a futile being, and his natural desire would be incapable of fulfillment, which is impossible. Now, it is clear from what has been said that man cannot understand separate substances on the basis of the foregoing opinions. So, man’s felicity is not located in such knowledge of separate substances.

Notes A nicer definition of futility you will not find.

3 Again, in order that the agent intellect be united to us as a form, so that we may understand separate substances through it, it is required that the generation of the habitual intellect be complete, according to Alexander; or that all objects of speculative understanding be made actual within us, according to Averroes.

And these two views reduce to the same thing, for in this explanation the habitual intellect is generated in us, in so far as the objects of speculative understanding are made actual within us. Now, all species from sensible things are potential objects of understanding. So, in order that the agent intellect be joined with any person, he must actually understand all the natures of sensible things, and all their powers, operations, and motions, through speculative understanding.

This is not possible for any man to know through the principles of the speculative sciences, by which principles we are moved to a connection with the agent intellect, as they say. For, one could not attain all these objects of knowledge from the things that come under the scope of our senses, and from which the principles of the speculative sciences are drawn. So, it is impossible for a man to achieve this connection, in the manner suggested by them. Therefore, it is not possible for man’s felicity to consist in such a connection.

Notes In other words, Science cannot and can never bring full understanding. The first paragraph of 4 is, though, outdated. Because now, of course, many men dare. Perhaps not for themselves, but for their progeny at (among other places) the “singularity.”

4 Besides, even granting that such a connection of man with the agent intellect were possible as they describe it, it is plain that such perfection comes to very few men; so much so that not even these men, nor any other men, however diligent and expert in speculative sciences, have dared to claim such perfection for themselves.

On the contrary, they all state that many things are unknown to them, Thus, Aristotle speaks of the squaring of the circle, and he can give only probable arguments for his principles for the ordering of celestial bodies, as he admits himself, in Book II of On the Heavens [5: 288a 2], and what is necessary in regard to these bodies and their movers he keeps for others to explain, in Metaphysics XI [8: 1073b 2]. Now, felicity is a definite common good, which many people can attain, “unless they are defective,” as Aristotle puts it, in Ethics I [9: 1099b 19]. And this is also true of every natural end in any species, that the members of this species do attain it, in most cases. Therefore, it is not possible for man’s ultimate felicity to consist in the aforesaid connection.

5 However, it is clear that Aristotle, whose view the aforementioned philosophers try to follow, did not think that man’s ultimate felicity is to be found in such a connection. For he proves, in Ethics I [13: 1102a 5], that man’s felicity is his operation according to perfect virtue. Hence, he had to develop his teaching on the virtues, which he divided into the moral and the intellectual virtues. Now, he shows in Book X [7: 1177a 18], that the ultimate felicity of man lies in speculation.

Hence, it clearly does not lie in the act of any moral virtue, nor of prudence or art, though these are intellectual virtues. It remains, then, that it is an operation in accord with wisdom, the chief of the three remaining intellectual virtues, which are wisdom, science, and understanding, as he points out in Ethics VI [6: 1141a 3].

Hence, in Ethics X [8: 1179a 32], he gives his judgment that the wise man is happy.

Now, wisdom, for him, is one of the speculative knowledges, “the head of the others,” as he says in Ethics VI [6]. And at the beginning of the Metaphysics [I, 1: 981b 26], he calls the science which he intends to treat in this work, wisdom. Therefore, it is clear that Aristotle’s opinion was that the ultimate felicity which man can acquire in this life is the kind of knowledge of divine things which can be gained through the speculative sciences. But that later way of knowing divine things, not by means of the speculative sciences but by a process of generation in the natural order, was made up by some of his commentators.

August 12, 2018 | No comments

Summary Against Modern Thought: A Second Misunderstanding of Separate Substances

Previous post.

Like last week, this chapter exists to squash a subtle, technical errors. Again it requires close reading to grasp. It’s best to at least skim: don’t skip. Reminder: An intellectual substance is an angel.

THAT WE CANNOT IN THIS LIFE UNDERSTAND SEPARATE SUBSTANCES IN THE WAY THAT AVERROES CLAIMED

1 Because there is very great difficulty in Alexander’s opinion, as a result of his supposition that the possible intellect in a condition of habituation is entirely corruptible, Averroes thought that be found an easier way to show that we sometimes understand separate substances. In fact, he asserted that the possible intellect is incorruptible and separate in being from us, as is also the agent intellect.

2 He showed, first of all, that it was necessary to hold that the agent intellect is related to principles naturally known to us, either as agent is to instrument, or as form to matter. For the habitual intellect, by which we understand, has not only this action of understanding, but also another, which is to make things actually understood; indeed, we know by experience that both actions stand within our power.

Now, the action of making things actual objects of understanding is more properly indicative of the meaning of habitual intellect than is the act of understanding, for to make things actually intelligible precedes the act of understanding them. But there are some things within us which are rendered actually understood in a natural way, not as a result of our effort or of the action of our will: such are the first intelligible things.

In fact, to make these actually understood does not depend on the habitual intellect, through which things that we know from study are made to be actually understood; rather, these first intelligibles are the starting point of the habitual intellect. And that is why the habit of these intelligibles is also called understanding by Aristotle, in Ethics VI [6: 1141a 7]. Now, they are made to be actually understood by the agent intellect alone. And by means of them other things are made to be actually understood: these are the things that we know from study. So, to make these subsequent things actually understood is the work both of the habitual intellect, as regards first principles, and of the agent intellect. Now, one action is not attributed to two things unless one of them is related to the other as agent to instrument or as form to matter. So, the agent intellect is necessarily related to the first principles of the habitual intellect either as agent to instrument or as form to matter.

Notes In this sentence is wisdom: “the action of making things actual objects of understanding is more properly indicative of the meaning of habitual intellect than is the act of understanding, for to make things actually intelligible precedes the act of understanding them.” You can learn a fact, but to assimilate it, really own it, is far more difficult. The “first intelligible things” are given by a certain form of induction.

3 In fact, he indicates how this is possible in the following way. Since the possible intellect, according to his theory, is a separate substance, it understands the agent intellect and the other separate substances, and also the first objects of speculative understanding. So, it is the subject for both types of objects. Now, whenever two things are united in one subject, one of them is like the form of the other. Thus, when color and light are present in a diaphanous body as their subject, one of them, namely, light, must be like the form of the other, namely, color. Now, this is necessary when they have an ordered relationship to each other, but not in the case of things accidentally associated in the same subject, like whiteness and musical ability. But speculatively understood things and the agent intellect do have an ordered relationship to each other, since the objects of speculative understanding are rendered actually understood by means of the agent intellect. So, the agent intellect is related to the objects of speculative understanding as form is to matter.

Therefore, when the objects of speculative understanding are united with us through the phantasms, which are in a sense their subject, the agent intellect must also be connected with us, because it is the form of the objects of speculative understanding. Thus, when the objects of speculative understanding are only potentially present in us, the agent intellect is only potentially connected with us. But, when some objects of speculative understanding are actually in us, and some are potentially present, its connection with us is partly actual and partly potential. Then it is that we are said to be in motion toward the aforementioned connection, for, as more things are made to be actually understood within us, the agent intellect becomes more perfectly connected with us. This progress and movement toward the connection is accomplished through study in the speculative sciences, through which we acquire true objects of understanding, and also false opinions that are outside the orderly process of this movement are excluded, just as monstrosities are outside the order of natural operation. Hence, men may help each other in making this progress, as they are of mutual assistance in the speculative sciences.

And so, when all potential objects of understanding have been made actual within us, the agent intellect is perfectly united with us as a form, and then we will understand perfectly through it, just as we now understand perfectly through the habitual intellect. Hence, since it is the function of the agent intellect to understand separate substances, we will then understand separate substances, as we now understand the objects of speculative understanding. And this will be the ultimate felicity of man, in which man will be “like some sort of God.”

Notes The key word is, of course, like. Knowledge is felicity!

4 Now, the refutation of this theory is sufficiently evident from the things that we have said earlier: in fact, it proceeds from the supposition of many points which are disproved in the foregoing sections.

5 First of all, we showed above that the possible intellect is not some substance separated from us in its being. Hence, it will not be necessary for it to be the subject of separate substances, especially since Aristotle says that the intellect is possible, “in that it is able to become all things.” From this we see that it is the subject only of those things that are made actually understood.

6 Again, we have shown above, concerning the agent intellect, that it is not a separate substance, but a part of the soul, to which Aristotle assigns this operation: “to make things actually understood” [De anima III, 5: 430a 14], and this lies within our power. Hence, it will not be necessary for the act of understanding—through the agent intellect to be the cause, for us, of our capacity to understand separate substances; otherwise, we would always understand them.

7 Furthermore, if the agent intellect is a separate substance, it cannot be joined to us except through species that have been made actually understood, according to this theory; and neither can the possible intellect, even though the possible intellect is related to these species as matter to form, while, conversely, the agent intellect is as form to matter.

Now, species that have been made actually understood are joined with us, according to his theory, by means of the phantasms which are related to the possible intellect as colors to the visual power, but to the agent intellect as colors to light: as we see from the words of Aristotle in Book in of On the Soul [III, 5: 430a 15]. But to the stone in which color is present, neither the action of the power of sight as it sees nor the action of the sun as it enlightens can be attributed. Therefore, according to the aforesaid theory, it would be impossible to attribute to man either the action of the possible intellect as it understands or the action of the agent intellect as it understands separate substances or as it makes things actually understood.

8 Besides, according to this theory, the agent intellect is not asserted to be connected with us as a form except by the fact that it is the form of objects of speculative understanding; and it is claimed to be the form of these objects because the same action belongs to the agent intellect and to these objects of understanding, which action is to make things actually understood. So, it could not be a form for us, unless by virtue of the fact that the objects of speculative understanding share in its action. Now, these objects do not share in its operation which consists in understanding separate substances, for they are the species of sensible things, unless we go back to the opinion of Avempace that the quiddities of separate substances can be known through the things that we understand about sensible objects. Therefore, it would not be at all possible for us to understand separate substances in the aforesaid way.

9 Moreover, the agent intellect is related to the objects of speculative understanding, which it makes to be so, in a different way from its relation to separate substances, which it does not make, but only knows, according to this theory. So, there is no necessity for it to be joined to us in its function as knower of separate substances, even if it is joined to us in its function as maker of the objects of speculative understanding. Rather, there is clearly a fallacy of accident in reasoning such as his.

10 Again, if we know separate substances through the agent intellect, this is not accomplished because the agent intellect is the form of this or that object of speculative understanding, but because it becomes a form for us, for in this way we are enabled to understand through it. Now, it becomes a form for us even through the first objects of speculative understanding, according to his own statement. Therefore, immediately at the start, man can know separate substances through the agent intellect.

11 Of course, it might be answered that the agent intellect does not become a form for us, in a perfect way, by virtue of certain objects of speculative understanding, so that we might understand separate substances through it and the only reason for this is that these objects of speculative understanding are not sufficient for the perfecting of the agent intellect in the act of understanding separate substances. But not even all the objects of speculative understanding taken together are sufficient for that perfection of the agent intellect by which it understands separate substances.

For all these objects are intelligible only in so far as they have been made to be understood, while those separate substances are intelligible by their own nature. So, not even the fact that we will know all the objects of speculative understanding will make it necessary for the agent intellect to become a form for us, in such a perfect way that we may understand separate substances through it. Or, if this is not required, then we will have to say that, in understanding any intelligible object, we understand separate substances.

August 5, 2018 | 1 Comment

Summary Against Modern Thought: A Misunderstanding of Separate Substances

Previous post.

This chapter, and the next, exist to squash a couple of subtle, technical errors. They require close reading to grasp. It’s best to at least skim: don’t skip. Reminder: An intellectual substance is an angel.

THAT WE CANNOT IN THIS LIFE UNDERSTAND SEPARATE SUBSTANCES IN THE WAY THAT ALEXANDER CLAIMED

1 Because Alexander [of Aphrodisias] claimed that the possible intellect is capable of being generated and corrupted, in the sense that it is “a perfection of human nature resulting from a mixture of the elements,” as we saw in Book Two, and since it is not possible for such a power to transcend material conditions, he maintained that our possible intellect can never reach an understanding of separate substances. Yet he asserted that, in our present state of life, we are able to understand separate substances.

2 In fact, he tried to show this in the following way. Whenever anything has reached maturity in its process of generation and has come to the full perfection of its substance, the operation proper to it will be at its peak, whether as action or as passion. For, as operation is consequent upon substance, so also is the perfection of operation a result of the perfection of substance. Hence, an animal, when it has become wholly perfect, is able to walk by itself.

Now, the habitual understanding which is simply “intelligible species made to exist in the possible intellect by the agent intellect” has a twofold operation: one, to make potentially understood things to be actually understood, and it owes this to the role of the agent intellect; and the second is actually to understand the objects of understanding.

These two things, then, man can do through an intellectual habit. So, whenever the generating of the habitual understanding has reached completion, both of these stated operations will be at their peak in it. Now, it always approaches the peak perfection of its generation when it acquires new kinds of objects of understanding. And thus, its process of generation must be completed at some time, unless there be an impediment, because no process of generation tends to an indefinite termination. So, it will reach completion whenever both operations are habitually present in the intellect, by virtue of the fact that it makes all the potential objects of understanding actual, which is the completion of the first operation, and because of the fact that it understands all intelligible objects, both separate and not separate.

3 Now, since according to his opinion the possible intellect cannot understand separate substances, as has already been said, he thought that we will understand separate substances through the habitual understanding, in so far as the agent intellect, which he supposes to be a separate substance, becomes the form of the habitual understanding, and a form for us ourselves. Thus, we will understand through it, as we now understand through the possible intellect; and since it is the function of the power of the agent intellect to make all things which are potentially intelligible to be actually understood, and to understand the separate substances, we will understand separate substances in this life, and also all non-separate intelligible things.

4 So, according to this theory, we reach the knowledge of separate substances through this knowledge which comes from the phantasms, not in the sense that these phantasms and the things understood through them are means for the knowing of separate substances (as is the case with the speculative sciences, according to the position advanced in the preceding chapter), but, rather, in so far as the intelligible species are certain dispositions within us to the kind of form that the agent intellect is. And this is the first point on which these two opinions differ.

5 Hence, when the habitual understanding will be perfected through the production in us by the agent intellect of these intelligible species, the agent intellect will itself become a form for us, as we have said. And he calls this the “acquired understanding,” which, according to their statement, Aristotle says comes from outside. And so, though the ultimate human perfection is not in the speculative sciences, as the preceding opinion claimed, man is disposed through these sciences to the attainment of the ultimate perfection. And this is the second point on which the first and second opinions differ.

6 However, they differ on a third point, because, according to the first opinion, our actual understanding of the agent intellect is the cause of its being united with us. Whereas, according to the second opinion, the converse is the case, for, since it is united with us as a form, we understand it and the other separate substances.

7 Now, these statements are unreasonable. Indeed, the habitual understanding, as also the possible understanding, is supposed by Alexander to be generable and corruptible. Now, the eternal cannot become the form of the generable and corruptible, according to him. For this reason, he claims that the possible intellect, which is united to us as a form, is generable and corruptible, while the agent intellect which is incorruptible is a separate substance. Hence, since the agent intellect, according to Alexander, is supposed to be an eternal separate substance, it will be impossible for the agent intellect to become the form of the habitual intellect.

8 Moreover, the form of the intellect, as intellect, is the intelligible object, just as the form of the sense is the sensible object; indeed, the intellect receives nothing, strictly speaking, except in an intellectual way, just as the sense power only receives sensitively. So, if the agent intellect cannot be an intelligible object through the habitual intellect, then it will be impossible for it to be its form.

9 Besides, we are said to understand something in three ways. First, as we understand by means of the intellect which is the power from which such an operation proceeds; hence, both the intellect itself is said to understand, and also the intellect’s act of understanding becomes our act of understanding. Second, we understand by means of an intelligible species; of course, we are not said to understand by it, in the sense that it understands, but because the intellective power is actually perfected by it, as the visual power is by the species of color. Third, we understand as by an intermediary through the knowing of which we come to the knowledge of something else.

10 So, if at some point man understands separate substances through the agent intellect, this must be explained by one of these ways that have been mentioned. Now, it is not explained by the third way, for Alexander did not admit that either the possible or the habitual intellect understands the agent intellect. Nor, indeed, is it in the second way, for to understand through an intelligible species is the attribute of the intellective power for which this intelligible species is the form.

Now, Alexander did not grant that the possible intellect or the habitual intellect understands separate substances; hence, it is not possible for us to understand separate substances through the agent intellect in the same way that we understand other things through an intelligible species. But, if it is as through an intellective power, then the agent intellect’s act of understanding must be man’s act of understanding. Now, this cannot be so unless one actual being is made from the substance of the agent intellect and the substance of man; indeed, it is impossible if they are two substances with different acts of being, for the operation of the one to be the operation of the other.

Therefore, the agent intellect will be one existing being with man, not one accidentally, for then the agent intellect would be not a substance but an accident, as is the case when a thing that is one being accidentally is made from color and a body. The conclusion remains, then, that the agent intellect is united with man in substantial being. It will be, then, either the human soul or a part of it, and not some separate substance as Alexander claimed. Therefore, it cannot be maintained, on the basis of Alexander’s opinion, that man understands separate substances.

11 Furthermore, if the agent intellect at any time becomes the form of one man, so that he is enabled to understand through it, by the same token it could become the form of another man similarly understanding through it. It will know, then, that two men will understand at the same time through the agent intellect as through their own form. This is so because the agent intellect’s own act of understanding is the act of understanding of the man who understands through it, as was said already. Therefore, there will be the same act of understanding for two intelligent beings; and this is impossible.

12 As a matter of fact, his theory is entirely frivolous. First of all because, whenever the process of generation is perfected in any member of a genus its operation must be perfected, but, of course, according to the manner of its own genus and not according to the mode of a higher genus. For instance, when the generation of air is perfected it has a development and complete movement upward, but not such that it is moved to the place proper to fire. Similarly, when the development of the habitual intellect is completed its operation of understanding will be completed according to its own mode, but not according to the mode whereby separate substances understand, so that it may understand separate substances. Hence, from the generation of the habitual intellect one cannot conclude that man will understand separate substance at some time.

13 Secondly, it is frivolous because the perfection of an operation belongs to the same power to which the operation itself belongs. So, if to understand separate substances be a perfection of the operation of the habitual intellect, it follows that the habitual intellect understands separate substances at some point in time. Now, Alexander does not claim this, for it would follow that to understand separate substances would depend on the speculative sciences which are included under the notion of habitual understanding.

14 Thirdly, it is frivolous because the generation of things that begin to be generated is nearly always brought to completion, since all processes of generating things are due to determinate causes which achieve their effects, either always, or in the majority of cases. If, then, the perfection of action also follows upon the completion of generation, it must also be the case that perfect operation accompanies the generated things, either always, or in the majority of cases. Now, the actual understanding of separate substances is not achieved by those who apply themselves to the development of habitual understanding, either in most cases or always; on the contrary, no man has openly declared that be had achieved this perfection. Therefore, the perfection of the operation of habitual understanding does not consist in the actual understanding of separate substances.

July 29, 2018 | 2 Comments

Summary Against Modern Thought: You Can’t Get To God Through Science

Previous post.

An intellectual substance is an angel. Grab yourself a quiet seat, dear reader; we have a long chapter ahead of us this week.

WHETHER IN THIS LIFE MAN IS ABLE TO UNDERSTAND SEPARATE SUBSTANCES THROUGH THE STUDY AND INVESTIGATION OF THE SPECULATIVE SCIENCES

1 An intellectual substance has still another kind of knowledge of God. Indeed, it has been stated in Book Two [96ff] that a separate substance, in knowing its own essence, knows both what is above and what is below itself, in a manner proper to its substance. This is especially necessary if what is above it is its cause, since the likeness of the cause must be found in the effects. And so, since God is the cause of all created intellectual substances, as is evident from the foregoing, then separate intellectual substances, in knowing their own essence, must know God Himself by way of a vision of some kind.

For a thing whose likeness exists in the intellect is known through the intellect by way of vision, just as the likeness of a thing which is seen corporeally is present in the sense of the viewer. So, whatever intellect understands a separate substance, by knowing what it is, sees God in a higher way than He is known by any of the previously treated types of knowledge.

Notes Regular readers will understand this kind of vision is a certain kind of induction; hence induction can be the highest form of knowledge.

Notes Recall a phantasm is a conglomeration of sense impressions, the stuff offered by your biology to your intellect.

2 Hence, since some men have claimed that man’s ultimate end is in this life, because they know separate substances, we must consider whether man can know separate substances in this life.

Now, on this point there is some dispute. For, our intellect in our present state understands nothing without a phantasm, and the phantasm is related to the possible intellect, whereby we understand, as colors are related to vision, as is evident from what we have treated in Book Two.

Therefore, if any of us could achieve the understanding of separate substances through the intellectual knowledge which is from phantasms, then it would be possible for a person in this life to understand separate substances themselves. Consequently, by seeing these separate substances one will participate in that mode of knowledge whereby the separate substance, while understanding itself, understands God. But, if one cannot in any way attain to the understanding of separate substances through the knowledge which depends on phantasms, then it will not be possible for man in the present state of life to achieve the aforesaid mode of divine knowledge.

Notes Recall quiddity is whatness or essence. Might help to think of quddities of quddities as higher abstractions.

3 Now, various people have claimed in different ways that we could reach an understanding of separate substances from the knowledge which is accomplished through phantasms.

For instance, Avempace claimed that, through the study of the speculative sciences, we can, on the basis of things understood through phantasms, reach an understanding of separate substances. For we can by the action of the intellect abstract the quiddity of anything that has a quiddity, and which is not identical with its quiddity.

Indeed, the intellect is naturally equipped to know any quiddity, in so far as it is quiddity, since the proper object of the intellect is what a thing is. But, if what is primarily understood by the possible intellect is something having a quiddity, we can abstract through the possible intellect the quiddity of that which is primarily understood. Moreover, if that quiddity also has a quiddity, it will in turn be possible to abstract the quiddity of this quiddity.

And since an infinite process is impossible, it must stop somewhere. Therefore, our intellect is able to reach, by way of resolution, the knowledge of a quiddity which has no further quiddity. Now, this is the sort of quiddity proper to a separate substance. So, our intellect can, through the knowledge of those sensible things that is received from phantasms, reach an understanding of separate substances.

4 He proceeds, moreover, to show the same thing in another, similar way. For he maintains that the understanding of one thing, say a horse, is plurally present in me and in you, simply by means of a multiplication of spiritual species which are diversified in me and in you. So, then, it is necessary that an object of understanding, which is not based on any species of this kind, be identical in me and in you.

But the quiddity of an object of understanding, which quiddity our intellect is naturally capable of abstracting, has no spiritual but individual species, as we have proved, because the quiddity of a thing that is understood is not the quiddity of an individual, either spiritual or corporeal, for a thing that is understood, as such, is universal. So, our intellect is by nature capable of understanding a quiddity for which the understanding is one among all men. Now, such is the quiddity of a separate substance. Hence, our understanding is naturally equipped to know separate substance.

5 However, if a careful consideration be made, these ways of arguing will be discovered to be frivolous. Since a thing that is understood, as such, is universal, the quiddity of the thing understood must be the quiddity of something universal; namely, of a genus or a species. Now, the quiddity of a genus or species pertaining to these sensible things, whose intellectual knowledge we get through phantasms, includes matter and form within itself. So, it is entirely unlike the quiddity of a separate substance, which latter is simple and immaterial. Therefore, it is not possible for the quiddity of a separate substance to be understood, simply because the quiddity of a sensible thing is understood through phantasms.

6 Besides, the form which in actual being cannot be separated from a subject is not of the same rational character as the form which is separated in its being from such a subject, even though both of them can be taken, in an act of consideration, without such a subject. Thus, there is not the same essential character for magnitude and for a separate substance, unless we claim that magnitudes are separate things midway between specific forms and sensible things, as some of the Platonists maintained.

Of course, the quiddity of a genus or species of sensible things cannot be separate in actual being from a given material individual, unless, perhaps, we maintain with the Platonists separate forms of things, but this has been disproved by Aristotle. Therefore, the quiddity of the aforementioned separate substances, which in no way exist in matter, is utterly different. Therefore, separate substances cannot be understood simply by virtue of the fact that these quiddities are understood.

7 Again, if it is granted that the quiddity of a separate substance is of the same rational character as the quiddity of a genus or species of these sensible things, that does not warrant saying that it is of the same rational character specifically, unless we say that the species of sensible things are themselves separate substances, as the Platonists claimed. The conclusion stands, then, that they will not be of the same rational character, except according to the rational character of quiddity as quiddity.

Now, this is a meaning of rational character which is common to genus and to substance. Therefore, nothing except their remote genus could be understood concerning separate substances through these sensible quiddities. Now, the fact that the genus is known does not mean that the species is known, except in potency. So, separate substances could not be understood through an understanding of the quiddities of these sensible things.

8 Moreover, there is a greater difference between separate substances and sensible things than between one sensible thing and another. But to understand the quiddity of one sensible thing is not enough to enable one to understand the quiddity of another sensible thing. For instance, a man who is born blind is not at all enabled to achieve understanding of the quiddity of color simply because he understands the quiddity of sound. Much less, then, is one enabled to understand the quiddity of a separate substance by the fact that he understands the quiddity of a sensible substance.

9 Furthermore, even if we claim that separate substances move the spheres, and that from their motions the forms of these sensible things are produced, this way of knowing separate substance, from sensible things, does not suffice for a knowing of their quiddity.

For a cause is known through an effect, either by reason of a likeness which exists between the effect and the cause or in so far as the effect shows the power of the cause.

Now, it would not be possible to know from the effect, by reason of likeness, what the cause is unless the agent is of one species with the effect. But that is not the way separate substances are related to sensible things. On the other hand, on the basis of power, this cannot be done except when the effect is equal to the power of the cause. For, in that case, the whole power of the cause is known through the effect, and the power of a thing demonstrates its substance. But this cannot be asserted in the present case, for the powers of separate substances exceed all the sensible effects which we may grasp intellectually, as a universal power surpasses a particular effect. Therefore, it is not possible for us to be enabled, through an understanding of sensible things, to come to an understanding of separate substance.

10 Again, all intelligible objects whose knowledge we reach through investigation and study belong to some one of the speculative sciences. So, if we attain the understanding of separate substances as a result of our understanding of the natures and quiddities of these sensible things, then it must be that the understanding of separate substances depends on one of the speculative sciences. Yet we do not observe this; there is no speculative science which teaches what any of the separate substances is, but only that they are. So, it is not possible for us to reach an understanding of separate substances simply because we understand sensible natures.

11 On the other hand, if it be suggested that such a speculative science is possible, even though it has not yet been discovered, this is no argument, because it is not possible to arrive at an understanding of the aforesaid substances through any principles known to us. Indeed, all the proper principles of any science depend on first indemonstrable principles, which are self-evident, and we get our knowledge of these from the senses, as is shown at the end of the Posterior Analytics. However sensible things are not adequate guides to the knowledge of immaterial things, as we have proved by the arguments above. Therefore, it is not possible for there to be any science whereby one might achieve understanding of separate substances.

Notes Whew!