De veritate EN 139



To obtain eternal life it is necessary to have faith in those things which are beyond the grasp of reason. We can understand this from what follows. For a thing is brought from imperfection to perfection only through the activity of something perfect. Nor does the imperfect thing at once in the very beginning fully receive the action of that which is perfect; at first it receives it imperfectly and, later, more perfectly. And it continues in this way until it reaches perfection. This is evident in all physical things, which acquire a perfection gradually.

We see the same thing in human works, especially in the learning process. For in the beginning a man has incomplete knowledge, and, if he is to reach the perfection of scientific knowledge, needs an instructor to bring him to that perfection. Nor could the teacher do this unless he himself had full knowledge of the science, that is unless he understood the intelligible principles of the things which form the subject matter of the science. At the outset of his teaching, however, he does not explain to his pupil the intelligible principles of the things to be known which he intends to teach, because then, at the very beginning, the pupil would [have to] know the science perfectly. In stead, the teacher proposes some things, the principles of which the pupil does not understand when first taught, but will know later when he has made some progress in the science. For this reason it is said that the learner must believe. And he could not acquire mastery of the science in any other way unless he accepted without proof those things which he is taught at first and the arguments for which he cannot then understand.

The final perfection toward which man is ordained consists in the perfect knowledge of God, which, indeed, man can reach only if God, who knows Himself perfectly, undertakes to teach him. Early in his life, however, man is not capable of receiving perfect knowledge. So, he has to accept certain things on faith and by means of these he is led on till he arrives at perfect knowledge.

Now, some of these things are such that they can never be perfectly known in this life, for they wholly transcend the power of human reason. These we must believe as long as we are in this life. However, we shah see them perfectly in heaven.

There are others which we can know perfectly in this life, as, for instance, the things which we can prove conclusively about God. Still, in the beginning, we have to believe these for five reasons, which Rabbi Moses gives. The first reason is the depth and subtlety of these objects of knowledge which are farthest removed from the senses. Hence, at the very beginning, man is not qualified to know them perfectly. The second reason is the weakness of human understanding when it begins to operate. The third is the number of things needed for a conclusive proof of these. And a man can learn them all only after a long time. The fourth reason is the disinclination for scientific investigation which some men have because they lack the proper temperament. The fifth is the need of engaging in other occupations to provide the necessities of life.

From all this it is clear that, if it were necessary to use a strict demonstration as the only way to reach a knowledge of the things which we must know about God, very few could ever construct such a demonstration and even these could do it only after a long time. From this it is evident that the provision of the way of faith, which gives all easy access to salvation at any time, is beneficial to man.

Answers to Difficulties:

1. In the constitution of man’s nature full provision is made for him, in so far as, to attain the end which is within the power of nature, he is given principles which are capable of causing that end. However, for the end which is beyond his natural ability man is given principles which are not a cause of the end, but which give him a capacity for those things which do bring him to his end. For this reason Augustine says: "The capacity to have faith and charity is due to man’s nature, but their actual possession is due to the grace which the faithful receive."

2. In the very beginning of creation, human nature was ordained to beatitude, not as to an end proper to man by reason of his nature, but given him solely by divine liberality. Therefore, there is no need for the principles of nature to have sufficient power to achieve that end without the aid of special gifts will which God in His generosity supplements them.

3. One who is some distance from an end can know the end and desire it; however, he cannot engage in activity- which directly concerns the end, but only in that which is connected will the means to the end. Therefore, if we are to reach our supernatural end, we need faith in this life to know the end, for natural knowledge does not go that far. But our natural powers do extend to the means to the end, although not precisely as ordained to that end. Therefore, we do not need infused habits for any other activity than that which natural reason dictates, but just for a more perfect performance of the same activity. However, this is not the case will knowledge for the reason given above.

4. Our understanding does not have a natural determination to matters of faith in the sense that it should know them naturally, but it does in some sense have a natural ordination to a knowledge of them in so far as nature is said to have an ordination to grace by reason of a divine decree. Consequently, this does not remove the need we have for the habit of faith.

5. Man is more perfect than the other animals. However, nature does not determine what is necessary for him to reach his end as it does for other animals, and this for two reasons. First, since man is ordained to a higher end, therefore, even though he needs more helps to reach that end and natural principles are not enough for him, he is nonetheless more perfect. Second, the very fact that he can have many ways to reach his end is a perfection in man. For this reason he cannot be limited to one natural way as other animals are. But, instead of all the means which nature provides for other animals, man is given reason, through which he can take care of the necessities of this life and make himself fit to receive the divine helps for the future life.

6. Credulity is called a vice because it means an excess of belief, just as to be a drinker means an excess in drinking. However, one who believes God does not believe immoderately, because we cannot put too much faith in Him. So, the conclusion does not follow.

7. The apostles and prophets under divine inspiration have never said anything contrary to the dictates of natural reason. Nevertheless, they have said things which are beyond the comprehension of reason, and so to this extent seem to contradict reason, although they do not really oppose it. In a similar way, to an unlettered person it seems contrary to reason to say that the sun is larger than the earth and the diagonal is incommensurable will the side. However, these appear reasonable to those who are educated.

8. It is because of its imperfection that faith is rendered use when glory arrives. And on this account it has a certain opposition to the perfection of glory. But, as far as the knowledge of faith is concerned, faith is necessary for salvation. For there is nothing unreasonable in the fact that something imperfect, which is directed to the perfection of the end, ceases to exist when the end is reached, as motion ceases to be when rest, which is its end, is reached.

9. Faith does not destroy reason, but goes beyond it and perfects it, as has been said above.

10. A heretic does not have the habit of faith even if it is only one article of faith which he refuses to believe. For infused habits are lost through one contrary act. And the habit of faith has this power, that through it the understanding of the believer is withheld from giving assent to things contrary to faith, just as chastity restrains us from acts opposed to chastity. Now, when a heretic believes something which is beyond the scope of natural knowledge, he does this not by reason of an infused habit, for such a habit would direct him equally to all objects of belief, but by reason of some human judgment, as happens also will pagans who believe certain things surpassing nature about God.

11. All the intermediaries through which faith comes to us are above suspicion. We believe the prophets and apostles because the Lord has been their witness by performing miracles, as Mark (16:20) says: and confirming the word will signs that followed." And we believe the successors of the apostles and prophets only in so far as they tell us those things which the apostles and prophets have left in their writings.

12. There are two kinds of difficulty, one arising from the nature of the work itself, and such difficulty has value for merit; the other arising from the disorder or sluggishness of the will. This latter rather lessens merit, and habit destroys it but not the former.

13. Natural powers have a determination to one object, and so do not need a habit to give them this determination as do the rational powers, which are related equally to things opposed to each other.


Parallel readings: I Sentences III Sentences 25, 2, 1, sol. 1, 2; Summa Theol., II—II, 2, 5.


It seems that it is not, for

We should not posit any proposition from which an untenable conclusion follows. But, if we claim that explicit belief is necessary for salvation, an untenable conclusion follows. For it is possible for someone to be brought up in the forest or among wolves, and such a one cannot have explicit knowledge of any matter of faith. Thus, there will be a man who will inevitably be damned. But this is untenable. Hence, explicit belief in something does not seem necessary.

2. We have no obligation to that which is not within our power.

But to believe something explicitly we have to hear it from within or without, for "faith cometh by hearing," as is said in Romans (10: 1). However, hearing is within the power of a person only if there is someone to speak. Thus, to believe something explicitly is not necessary for salvation.

3. Very subtle matters should not be taught to the uneducated. But there is nothing more subtle on more exalted than things which are beyond reason, such as the articles of faith. Therefore, such things should not be taught to the people. Therefore, at least not everybody is required to believe something explicitly.

4. Man is not bound to know that which even the angels do not know. But before the Incarnation the angels did not know the mystery of the Incarnation, as Jerome seems to say. Therefore, the men of those times, at least, were not bound to know or believe something explicitly about the Redeemer.

5. Many Gentiles were saved before the coming of Christ, as Dionysius says. However, they could know nothing explicitly about the Redeemer, since the prophets had not come to them. Therefore, explicit belief in the articles about the Redeemer does not seem necessary for salvation.

6. One of the articles of faith about the Redeemer concerns the descent into hell [that is, limbo]. But, according to Gregory, John doubted about this article when he asked: "Art thou he that art to come?" (Mt 11,3). Therefore, since he is one of the greater men, for no one is greater than he, as is said in the same passage, it seems that even the greater men are not bound to know explicitly the articles about the Redeemer.

To the Contrary:

1’. Explicit belief in everything seems necessary for salvation, for everything pertains to faith in the same way. So, everything has to be believed explicitly for the same reason that one truth has to be believed explicitly.

2’. Everyone is bound to avoid all errors which are against the faith. This can be done only by having explicit knowledge of all the articles which the errors oppose. Therefore, we have to have explicit belief in all the articles.

3’. As commands direct our action, so articles direct our belief. But everyone is bound to know all the commandments of the Decalogue, for a man is not excused if he commits some sin through ignorance of the commandments. Therefore, everyone is also bound to believe all the articles explicitly.

4’. Just as God is the object of faith, so, also, He is the object of charity. But we should not love anything implicitly in God. There fore, neither should we believe anything implicitly about Him.

5’. A heretic, however uneducated, is questioned about all the articles of faith. This would not be done if he were not bound to believe all of them explicitly. This brings us to the same conclusion as before.

6’. The habit of faith is specifically the same in all believers. If, then, some of the faithful must believe everything explicitly, all are bound to the same thing.

7’. Formless faith is not enough for salvation. But to believe implicitly is to have formless faith, for superiors on whose faith depends the faith of uneducated people, who believe implicitly, often have formless faith. Therefore, to believe implicitly is not enough for salvation.



Properly speaking, that is called implicit in which many things are contained as in one, and that is called explicit in which each of the things is considered in itself. These appellations are transferred from bodily to spiritual things. When a number of things are contained virtually in one thing, we say they are there implicitly, as, for instance, conclusions in principles. A thing is contained explicitly in another if it actually exists in it. Consequently, one who knows some general principles has implicit knowledge of all the particular conclusions. One, however, who actually considers the conclusions is said to know them explicitly. Hence, we are also said explicitly to believe certain things when we affirm those things about which we are actually thinking. We believe these same things implicitly when we affirm certain other things in which they are contained as in general principles. Thus, one who believes that the faith of the Church is true, implicitly in this believes the individual points which are included in the faith of the Church.

We must note, accordingly, that there are some matters of faith which everyone is bound to believe explicitly in every age. Other matters of faith must believe explicitly in every age but not by every one. Still other matters everyone must believe explicitly, but not in every age. And, finally, there are things that need not be believed explicitly by everyone nor in every age.

That all the faithful in every age must believe something explicitly is evident from the fact that there is a parallel between the reception of faith will reference to our ultimate perfection and a pupil’s reception of those things which his master first teaches him, and through which he is guided to prior principles. However, he could not be so guided unless he actually considered something. Hence, the pupil must receive something for actual consideration; likewise, the faithful must explicitly believe something. And these are the two things which the Apostle tells us must be believed explicitly: "For he that cometh to God must believe that He is, and is the rewarder to them that love Him" (He 11,6). Therefore, everyone in every age is bound explicitly to believe that God exists and exercises providence over human affairs.

However, it is not possible for anyone in this life to know explicitly the whole of God’s knowledge, in which our beatitude consists. Yet it is possible for someone in this life to know all those things which are proposed to the human race in its present state as first principles will which to direct itself to its final end. Such a person is said to have faith which is completely explicit. But not all believers have this completeness; hence, there are levels of belief in the Church, so that some are placed over others to teach them in matters of faith. Consequently, not all are required explicitly to believe all matters of faith, but only those are so bound who are appointed teachers in matters of faith, such as superiors and those who have pastoral duties.

And even these are not bound to believe everything explicitly in every age. For there is a gradual progress in faith for the whole human race just as there is for individual men. This is why Gregory says that down the ages there has been a growing development of divine knowledge.

Now, the fullness of time, which is the prime of life of the human race, is in the age of grace. So, in this age, the leaders are bound to believe all matters of faith explicitly. But, in earlier ages, the leaders were not bound to believe everything explicitly. However, more had to be believed explicitly after the age of the law and the prophets than before that time.

Accordingly, before sin came into the world, it was not necessary to believe explicitly the matters concerning the Redeemer, since there was then no need of the Redeemer. Nevertheless, this was implicit in their belief in divine providence, in so far as they believed that God would provide everything necessary for the salvation of those who love Him. Before and after the fall, the leaders in every age had to have explicit faith in the Trinity. Between the fall and the age of grace, however, the ordinary people did not have to have such explicit belief. Perhaps before the fall there was not such a distinction of persons that some had to be taught the faith by others. Likewise, between the fail and the age of grace, the leading men had to have explicit faith in the Redeemer, and the ordinary people only implicit faith. This was contained either in their belief in the faith of the patriarchs and prophets or in their belief in divine providence.

However, in the time of grace, everybody, the leaders and the ordinary people, have to have explicit faith in the Trinity and in the Redeemer. However, only the leaders, and not the ordinary people, are bound to believe explicitly all the matters of faith concerning the Trinity and the Redeemer. The ordinary people must, however, believe explicitly the general articles, such as that God is triune, that the Son of God was made flesh, died, and rose from the dead, and other like matters which the Church commemorates in her feasts.

Answers to Difficulties:

1. Granted that everyone is bound to believe something explicitly, no untenable conclusion follows even if someone is brought up in the forest or among will beasts. For it pertains to divine providence to furnish everyone will what is necessary for salvation, provided that on his part there is no hindrance. Thus, if someone so brought up followed the direction of natural reason in seeking good and avoiding evil, we must most certainly hold that God would either reveal to him through internal inspiration what had to be believed, or would send some preacher of the faith to him as he sent Peter to Cornelius (Acts 10:20).

2. Although it is not within our power to know matters of faith by ourselves alone, still, if we do what we can, that is, follow the guidance of natural reason, God will not withhold from us that which we need.

3. Matters of faith are not presented to the uneducated for minute explanation, but in a general way, for in this way they have to believe them explicitly as has been said.

4. According to Dionysius and Augustine, the angels knew the mystery of the Incarnation of Christ before men did, since it was through the angels that the prophets were told of the Incarnation. But Jerome says that the angels learned this mystery through the Church, in so far as the mystery of the salvation of the Gentiles was fulfilled through the preaching of the Apostles. In this way, their knowledge was more complete will reference to certain circumstances, since they now saw as present what they had foreseen as future.

5. The Gentiles were not established as teachers of divine faith. Hence, no matter how well versed they were in secular wisdom, they should be counted as ordinary people. Therefore, it was enough for them to have implicit faith in the Redeemer, either as part of their belief in the faith of the law and the prophets, or as part of their belief in divine providence itself. Nevertheless, it is likely that the mystery of our redemption was revealed to many Gentiles before Christ’s coming, as is clear from the Sibylline prophecies.

6. Although John the Baptist should be counted among the greater persons of his time because God made him a herald of truth, it was not necessary for him to believe explicitly all the matters of revelation which are explicitly believed after Christ’s passion and resurrection in the age of grace. For, in his time, the knowledge of the truth had not reached the fullness which it received especially will the coming of the Holy Spirit. Some, however, say that in this passage John did not ask personally for himself, but for his disciples who doubted about Christ. Some also say that this was the question not of one who doubted but of one who had a holy admiration for the humility of Christ, that He would deign to descend into hell.

Answers to Contrary Difficulties:

1'. All things which pertain to faith do not have the same rational connection will the direction of man to his final end, for some are more obscure than others and some are more necessary to it than others. Therefore, some articles rather than others must be believed explicitly.

2'. One who does not believe all the articles explicitly can still avoid all errors because the habit of faith keeps him from giving assent to things against the articles which he knows only implicitly. Thus, for instance, if something unusual is proposed, he is suspicious of it and delays assent until he gets instruction from him whose duty it is to decide about doubtful matters of faith.

3’. The commandments of the Decalogue deal will things that are dictated by natural reason. Therefore, everyone is required to know them explicitly. A similar argument cannot be used for the articles of faith, which are above reason.

4’. Love is distinguished into implicit and explicit only in so far as it follows faith. For love terminates at some individual thing existing outside the soul, whereas knowledge terminates at that which is within the perception of the soul, which can perceive something in general or in particular. Therefore, faith and charity do not work in the same way.

5’. An uneducated person who is accused of heresy is not examined on all the articles of faith because he must believe them all explicitly, but because he must not obstinately maintain the opposite of any of the articles.

6’. That some of the faithful must believe explicitly what others have to believe only implicitly does not come from a difference in the habit of faith, but from different duties. For one who is made a teacher of the faith should know explicitly those things which he must or ought to teach. And the higher his position is, the more perfect a knowledge of matters of faith he should have.

7’. Ordinary people do not have implicit faith in the faith of some particular men, but in the faith of the Church, which cannot be form less. Furthermore, one is said to have implicit faith in the faith of another, because of an agreement in belief, and not because they have the same mode of informed or formless faith.


Parallel readings: III Sentences 25, 2, 2, sol. I; Summa Theol., II-II, I, 7; 2, 7; 174, 6.


It seems that there is not, for

1. Universal knowledge differs from particular knowledge. But the ancients knew the matters of faith as it were in general, believing them implicitly, whereas modems believe them explicitly and in particular. Therefore, the faith of the ancients and modems is not the same.

2. Faith concerns a proposition. But the propositions which we believe are not the same as the ones they believed, as, for instance, Christ will be born, and Christ has been born. Therefore, our faith is not the same as that of the ancients.

3. In matters of faith a definite time is a necessary element of belief. Thus, a man would be called an unbeliever if he believed that Christ had not yet come, but would come. But there is temporal variation

in our faith and that of the ancients, for we believe about the past what they believed about the future. Hence, our faith and that of the ancients is not the same.

To the Contrary:

1'. In Ephesians (4:5) we read: "One Lord, one faith, one baptism."



We must firmly hold that there is one faith for ancients and moderns; otherwise, there would not be one Church. To support this position some have said that the proposition about the past which we believe and the one about the future which the ancients believed is the same proposition. But it does not seem right that the proposition should remain the same when its essential parts are changed. For we see that propositions are changed by reason of changes in the subject and verb.

For this reason, others have said that the propositions which we believe and which they believed are different, but that faith does not concern propositions but things. The thing, however, is the same, al though the propositions are different. For they say that it belongs intrinsically to faith to believe in the resurrection of Christ, but only accidentally to faith to believe that it is or was. But this is obviously false, for, since belief is called assent, it can only be about a proposition, in which truth or falsity is found. Thus, When I say: "I believe in the resurrection," I must understand some union [of subject and predicate]. And I must do this will reference to some time which the soul always adds in affirmative and negative propositions, as is said in The Soul. Accordingly, the sense of "I believe in the resurrection" is this: "I believe that the resurrection is, was, or will be."

Therefore, we must say that the object of faith can be considered in two ways. First, we have the object in itself as it exists outside the soul. And it is properly in this sense that it has the character of object and is the reason why habits are one or many. Second, we have the object as it exists in the knower as participated by him. Accordingly, we have to say that, if we take as the object of faith the thing believed as it exists outside the soul, it is in this way that each thing is related to us and to the ancients. And faith gets its unity from the oneness of the object. However, if we consider faith as it is in our perception of it, it is multiplied according to different propositions. But faith is not differentiated by this diversity. From this it is evident that faith is one in every way.

Answers to Difficulties:

1. To know in general and in particular differentiates knowledge only will reference to the manner of knowing, not will reference to the thing known, from which the habit has its unity.

2. The answer to the second difficulty is clear from what has been           said.

3. Time does not change because of something in the thing, but because of relation to us or the ancients. For there is one time in which Christ suffered. Under different aspects it is called past or future for people in comparison will things which precede or follow.

QUESTION 15: Lower Reason


Parallel readings: III Sentences 35, 2, 2, sol. I; Summa Theol., I, 8.


It seems that they are, for

1. In Spirit and Soul we read: "When we want to rise from lower to higher things, first, senses come to our aid; then, imagination; then, reason; then, understanding; then, intelligence; and, in the highest place, there is wisdom, which is God Himself." But imagination and sense are different powers. Therefore, reason and understanding are, too.

2. As Gregory says, man has something in common will every creature, and for this reason is man called all creation. However, that by which man has something in common will plants is a power of the soul, the vegetative, which is distinct from reason, the proper power of man, as man. The same is true for the senses, by which he has something in common will brute animals. Therefore, will equal reason, his understanding, which he has in common will angels, who are above man, is a power different from reason, which is proper to the human race, as Boethius says.

3. Just as the perceptions of the proper senses terminate at the common sense, which makes judgments concerning them, so the discourse of reason terminates at understanding, so that judgment may be made about the things which reason has compared. For man judges of the things which reason compares when by analysis he reaches principles which are the objects of understanding. For this reason the art of judging is called analytical. Therefore, as common sense is a different power from proper sense, so understanding is different from reason.

4. To comprehend and to judge are acts requiring different powers, as is clear in proper and common sense. For common sense judges about the things which proper sense perceives. But, as is said in Spirit and Soul: "Whatever sense perceives, imagination represents, thought forms, genius investigates, reason judges, memory retains, and intelligence comprehends." Therefore, reason and intelligence are different powers.

5. That which is simply composite relates to simple act in the way as that which is altogether simple relates to composite act. But the divine intellect, which is simple in every way, has no composite act, but only the most simple act. Therefore, our reason, which is composite, inasmuch as it compares, does not have a simple act. But the act of understanding is simple, "for it is understanding of things in divisible," as is said in The Soul. Therefore, understanding and reason are not one power.

6. According to the Commentator and the Philosopher, the rational soul knows itself through a likeness. "The mind, however, in which the image resides, knows itself through itself," according to Augustine. Therefore, reason and mind, or understanding, are not the same.

7. Powers are differentiated according to acts, and acts according to objects. But the objects of reason and understanding differ very greatly. For, as is said in Spirit and Soul: "The soul perceives bodies by sense, likenesses of bodies by imagination, natures of bodies by reason, created spirit by understanding, and uncreated spirit by intelligence." But bodily nature differs very greatly from created spirit. Therefore, understanding and reason are different powers.

8. Boethius says: "Sense, imagination, reason, and intelligence each look on man in a different way. Sense sees figure embodied in given matter, whereas imagination judges of figure alone without matter. Reason, in its turn, transcends imagination, examining will general consideration the species which exists in singular things. Moreover, the eye of intelligence has a more lofty existence, for intelligence goes beyond the scope of the universe and by sheer force of mind surveys simple form itself." Therefore, just as imagination is a power different from sense, since imagination considers form outside of matter, and sense sees it embodied in matter, so intelligence, which considers form absolutely, is a power different from reason, which studies the general form as it exists in individual things.

9. Boethius says: "As reasoning is related to understanding, as that which is produced, to that which exists, as time to eternity, and as the circle to its center point, so the changeable series of fate is related to the stable simplicity of providence." But it is plain that there is an essential difference between providence and fate, between the circle and its center, between time and eternity, and between generation and existence. Therefore, reason, too, is essentially different from under standing.

10. As Boethius says: "Reason belongs to the human race alone, as intelligence belongs only to the divine." But the divine and the human cannot both share in the one essence of power. Therefore, they are not one power.

11. The order of powers follows the order of acts. But to receive something absolutely, which seems to belong to understanding, is prior to comparison, which belongs to reason. Therefore, understanding is prior to reason. But nothing is prior to itself. Therefore, understanding and reason are not the same power.

12. It is one thing to consider the entity of a thing absolutely, and another to consider it as in this thing. The human soul exercises both of these considerations. Therefore, in the human soul there must be two powers, one to know the absolute entity, which is understanding, and another to know the entity in something else, which seems to be reason. We conclude as before.

13. In Spirit and Soul we read: "Reason is the sight of the mind by which it distinguishes good and evil, chooses virtues, and loves God." These things seem to belong to the affections which are a different power from the understanding. Therefore, reason, too, is a different power from the understanding.

14. The rational is distinguished from the concupiscible and irascible. But the irascible and concupiscible belong to the appetites. There fore, reason does, also. We conclude as before.

15. The Philosopher says: "The will is in the rational part." But it is distinguished from understanding. We conclude as before.

To the Contrary:

1'. Augustine seems to say the opposite when he says: "We arrive at the image of God, which is man, in that by which he surpasses other animals, that is, in reason or intelligence. And whatever else there is of the rational or intellectual soul can be said to belong to that thing which is called mind or mental life." From this it seems that he takes reason and intelligence as the same thing.

2’. In Augustine (and in the Gloss on Ephesians [4:33]: "And be renewed in the spirit of your mind,") we read: "We should under stand that man is made in the image of God in that by which he surpasses irrational animals." But this is reason itself, mind, intelligence, or whatever other name fits it better. Therefore, it seems that reason and understanding are for Augustine different names for the same power.

3’. Augustine says: "The image of that nature than which no nature is better should be sought and found in us in that than which our nature, also, has nothing better." But the image of God is in us in the higher part of reason, as is said in The Trinity. Therefore, there is no other power in man better than reason. But, if intelligence or under standing were different from reason, they would be above reason, as is clear from the citations from Boethius and Spirit and Soul mentioned above. Therefore, in man, understanding is not a different power from reason.

4’. The more immaterial a power is, the more it can extend to many things. But common sense, which is a material power, institutes comparisons of proper sensibles by distinguishing them from one another, and also has knowledge of them separately. Otherwise, it would not be able to distinguish one from another, as is proved in The Soul. Therefore, it is much more certain that reason, which is a more immaterial power, can not only compare, but also perceive things separately, a function which belongs to understanding. Thus, understanding and reason do not seem to be different powers.

5’. As is said in Spirit and Soul: "The mind, capable of receiving everything, and stamped will the likeness of all things, is said to be the soul and to be a nature will a certain power and natural dignity." But that which designates the whole soul should not be distinguished from some power of the soul. Therefore, the mind, which is a power of the soul, should not be distinguished from reason. Similarly, understanding, which seems to be the same thing as mind, should not be distinguished from it.

6’. There is a double composition in the activity of the human soul. There is one by which it joins and divides predicate and subject, by forming propositions. The other is that by which it joins by comparing principles will conclusions. In the first composition the same power of the human soul apprehends the simple things, that is, predicate and subject, through their quiddities, and forms a proposition by joining them. For both of these are attributed to the possible intellect, according to The Soul. Therefore, will like reason there will be one power which grasps principles, a function which belongs to understanding, and which orders principles to conclusions, a function which belongs to reason.

7’. In Spirit and Soul we read: "The soul is an intellectual or rational spirit." From this it seems that reason is the same as understanding.

8’. Augustine says: "As soon as something arises which is not common to us and animals, it belongs to reason." This same thing also belongs to understanding, according to the Philosopher. Therefore, reason and understanding are the same.

9'. Difference of objects in their accidental qualities does not indicate diversity of faculties. For a colored man and a colored stone are perceived by the same sensitive faculty, since it is incidental to the sensible thing in so far as it is a sensible thing, to be a man or a stone. But the objects which are ascribed to reason and understanding in Spirit and Soul, that is, "created spirit" and "corporeal nature," do not differ, but agree, in their essential character as object of knowledge. For, just as a created incorporeal spirit is intelligible because it is immaterial, so, too, bodily natures are objects of understanding only in so far as they are separated from matter. Thus, both of these, in so far as they are known, share in one character of cognoscibility, the character of immateriality. Therefore, reason and understanding are not different powers.

10’. Every power that compares two things will each other must have knowledge of each separately. Hence, the Philosopher proves that in us there must be one power which knows "white and sweet" because we can distinguish between them. But, just as one who distinguishes between different things relates them to each other, so also, he who compares them relates one to the other. Therefore, it also be longs to the power which compares, namely, reason, to know some thing separately, which is an activity of understanding.

11'. It is more noble to compare than to be compared, just as it is more noble to act than to be acted upon. But a thing is understood and compared through the same thing. Therefore, the soul, also, under stands and compares through the same thing. Therefore reason and understanding are the same.

12’. One habit does not exist in different powers. But it is possible for us to compare and perceive something separately by the same habit. Thus, faith, which perceives a thing separately, in so far as it clings to first truth, also compares, to the extent that by a sort of reasoning it sees first truth mirrored in creatures. Therefore, it is the same power which compares and which perceives something separately.

De veritate EN 139