Summa Th. I EN Qu.3 a.5

Whether God is contained in a genus?

Objection: 1. It seems that God is contained in a genus. For a substance is a being that subsists of itself. But this is especially true of God. Therefore God is in a genus of substance.

2. Further, nothing can be measured save by something of its own genus; as length is measured by length and numbers by number. But God is the measure of all substances, as the Commentator shows (Metaph. x). Therefore God is in the genus of substance.

On the contrary In the mind, genus is prior to what it contains. But nothing is prior to God either really or mentally. Therefore God is not in any genus.

I answer that A thing can be in a genus in two ways; either absolutely and properly, as a species contained under a genus; or as being reducible to it, as principles and privations. For example, a point and unity are reduced to the genus of quantity, as its principles; while blindness and all other privations are reduced to the genus of habit. But in neither way is God in a genus. That He cannot be a species of any genus may be shown in three ways.
1. First, because a species is constituted of genus and difference. Now that from which the difference constituting the species is derived, is always related to that from which the genus is derived, as actuality is related to potentiality. For animal is derived from sensitive nature, by concretion as it were, for that is animal, which has a sensitive nature. Rational being, on the other hand, is derived from intellectual nature, because that is rational, which has an intellectual nature, and intelligence is compared to sense, as actuality is to potentiality. The same argument holds good in other things. Hence since in God actuality is not added to potentiality, it is impossible that He should be in any genus as a species.
2. Secondly, since the existence of God is His essence, if God were in any genus, He would be the genus "being", because, since genus is predicated as an essential it refers to the essence of a thing. But the Philosopher has shown (Metaph. iii) that being cannot be a genus, for every genus has differences distinct from its generic essence. Now no difference can exist distinct from being; for non-being cannot be a difference. It follows then that God is not in a genus.
3. Thirdly, because all in one genus agree in the quiddity or essence of the genus which is predicated of them as an essential, but they differ in their existence. For the existence of man and of horse is not the same; as also of this man and that man: thus in every member of a genus, existence and quiddity---i.e. essence---must differ. But in God they do not differ, as shown in the preceding article. Therefore it is plain that God is not in a genus as if He were a species. From this it is also plain that He has no genus nor difference, nor can there be any definition of Him; nor, save through His effects, a demonstration of Him: for a definition is from genus and difference; and the mean of a demonstration is a definition. That God is not in a genus, as reducible to it as its principle, is clear from this, that a principle reducible to any genus does not extend beyond that genus; as, a point is the principle of continuous quantity alone; and unity, of discontinuous quantity. But God is the principle of all being. Therefore He is not contained in any genus as its principle.

Reply to Objection: 1. The word substance signifies not only what exists of itself---for existence cannot of itself be a genus, as shown in the body of the article; but, it also signifies an essence that has the property of existing in this way---namely, of existing of itself; this existence, however, is not its essence. Thus it is clear that God is not in the genus of substance.

2. This objection turns upon proportionate measure which must be homogeneous with what is measured. Now, God is not a measure proportionate to anything. Still, He is called the measure of all things, in the sense that everything has being only according as it resembles Him.

Whether in God there are any accidents?

Objection: 1. It seems that there are accidents in God. For substance cannot be an accident, as Aristotle says (Phys. i). Therefore that which is an accident in one, cannot, in another, be a substance. Thus it is proved that heat cannot be the substantial form of fire, because it is an accident in other things. But wisdom, virtue, and the like, which are accidents in us, are attributes of God. Therefore in God there are accidents.

2. Further, in every genus there is a first principle. But there are many "genera" of accidents. If, therefore, the primal members of these genera are not in God, there will be many primal beings other than God---which is absurd.

On the contrary Every accident is in a subject. But God cannot be a subject, for "no simple form can be a subject", as Boethius says (De Trin.). Therefore in God there cannot be any accident.

I answer that From all we have said, it is clear there can be no accident in God.
1. First, because a subject is compared to its accidents as potentiality to actuality; for a subject is in some sense made actual by its accidents. But there can be no potentiality in God, as was shown (Question [2], Article [3]).
2. Secondly, because God is His own existence; and as Boethius says (Hebdom.), although every essence may have something superadded to it, this cannot apply to absolute being: thus a heated substance can have something extraneous to heat added to it, as whiteness, nevertheless absolute heat can have nothing else than heat.
3. Thirdly, because what is essential is prior to what is accidental. Whence as God is absolute primal being, there can be in Him nothing accidental. Neither can He have any essential accidents (as the capability of laughing is an essential accident of man), because such accidents are caused by the constituent principles of the subject. Now there can be nothing caused in God, since He is the first cause. Hence it follows that there is no accident in God.

Reply to Objection: 1. Virtue and wisdom are not predicated of God and of us univocally. Hence it does not follow that there are accidents in God as there are in us.

2. Since substance is prior to its accidents, the principles of accidents are reducible to the principles of the substance as to that which is prior; although God is not first as if contained in the genus of substance; yet He is first in respect to all being, outside of every genus.

Whether God is altogether simple?

Objection: 1. It seems that God is not altogether simple. For whatever is from God must imitate Him. Thus from the first being are all beings; and from the first good is all good. But in the things which God has made, nothing is altogether simple. Therefore neither is God altogether simple.

2. Further, whatever is best must be attributed to God. But with us that which is composite is better than that which is simple; thus, chemical compounds are better than simple elements, and animals than the parts that compose them. Therefore it cannot be said that God is altogether simple.

On the contrary Augustine says (De Trin. iv, 6,7): "God is truly and absolutely simple."

I answer that The absolute simplicity of God may be shown in many ways.
1. First, from the previous articles of this question. For there is neither composition of quantitative parts in God, since He is not a body; nor composition of matter and form; nor does His nature differ from His "suppositum"; nor His essence from His existence; neither is there in Him composition of genus and difference, nor of subject and accident. Therefore, it is clear that God is nowise composite, but is altogether simple.
2. Secondly, because every composite is posterior to its component parts, and is dependent on them; but God is the first being, as shown above (Question [2], Article [3]).
3. Thirdly, because every composite has a cause, for things in themselves different cannot unite unless something causes them to unite. But God is uncaused, as shown above (Question [2], Article [3]), since He is the first efficient cause.
4. Fourthly, because in every composite there must be potentiality and actuality; but this does not apply to God; for either one of the parts actuates another, or at least all the parts are potential to the whole.
5. Fifthly, because nothing composite can be predicated of any single one of its parts. And this is evident in a whole made up of dissimilar parts; for no part of a man is a man, nor any of the parts of the foot, a foot. But in wholes made up of similar parts, although something which is predicated of the whole may be predicated of a part (as a part of the air is air, and a part of water, water), nevertheless certain things are predicable of the whole which cannot be predicated of any of the parts; for instance, if the whole volume of water is two cubits, no part of it can be two cubits. Thus in every composite there is something which is not it itself. But, even if this could be said of whatever has a form, viz. that it has something which is not it itself, as in a white object there is something which does not belong to the essence of white; nevertheless in the form itself, there is nothing besides itself. And so, since God is absolute form, or rather absolute being, He can be in no way composite. Hilary implies this argument, when he says (De Trin. vii): "God, Who is strength, is not made up of things that are weak; nor is He Who is light, composed of things that are dim."

Reply to Objection: 1. Whatever is from God imitates Him, as caused things imitate the first cause. But it is of the essence of a thing to be in some sort composite; because at least its existence differs from its essence, as will be shown hereafter, (Question [4], Article [3]).

2. With us composite things are better than simple things, because the perfections of created goodness cannot be found in one simple thing, but in many things. But the perfection of divine goodness is found in one simple thing (Question [4], Article [1] and Question [6], Article [2]).

Whether God enters into the composition of other things?

Objection: 1. It seems that God enters into the composition of other things, for Dionysius says (Coel. Hier. iv): "The being of all things is that which is above being---the Godhead." But the being of all things enters into the composition of everything. Therefore God enters into the composition of other things.

2. Further, God is a form; for Augustine says (De Verb. Dom., [*Serm. xxxviii]) that, "the word of God, which is God, is an uncreated form." But a form is part of a compound. Therefore God is part of some compound.

3. Further, whatever things exist, in no way differing from each other, are the same. But God and primary matter exist, and in no way differ from each other. Therefore they are absolutely the same. But primary matter enters into the composition things. Therefore also does God. Proof of the minor---whatever things differ, they differ by some differences, and therefore must be composite. But God and primary matter are altogether simple. Therefore they nowise differ from each other.

On the contrary Dionysius says (Div. Nom. ii): "There can be no touching Him," i.e. God, "nor any other union with Him by mingling part with part."

Further, the first cause rules all things without commingling with them, as the Philosopher says (De Causis).
I answer that On this point there have been three errors. Some have affirmed that God is the world-soul, as is clear from Augustine (De Civ. Dei vii, 6). This is practically the same as the opinion of those who assert that God is the soul of the highest heaven. Again, others have said that God is the formal principle of all things; and this was the theory of the Almaricians. The third error is that of David of Dinant, who most absurdly taught that God was primary matter. Now all these contain manifest untruth; since it is not possible for God to enter into the composition of anything, either as a formal or a material principle.
1. First, because God is the first efficient cause. Now the efficient cause is not identical numerically with the form of the thing caused, but only specifically: for man begets man. But primary matter can be neither numerically nor specifically identical with an efficient cause; for the former is merely potential, while the latter is actual.
2. Secondly, because, since God is the first efficient cause, to act belongs to Him primarily and essentially. But that which enters into composition with anything does not act primarily and essentially, but rather the composite so acts; for the hand does not act, but the man by his hand; and, fire warms by its heat. Hence God cannot be part of a compound.
3. Thirdly, because no part of a compound can be absolutely primal among beings---not even matter, nor form, though they are the primal parts of every compound. For matter is merely potential; and potentiality is absolutely posterior to actuality, as is clear from the foregoing (Question [3], Article [1]): while a form which is part of a compound is a participated form; and as that which participates is posterior to that which is essential, so likewise is that which is participated; as fire in ignited objects is posterior to fire that is essentially such. Now it has been proved that God is absolutely primal being (Question [2], Article [3]).

Reply to Objection: 1. The Godhead is called the being of all things, as their efficient and exemplar cause, but not as being their essence.

2. The Word is an exemplar form; but not a form that is part of a compound.

3.: Simple things do not differ by added differences---for this is the property of compounds. Thus man and horse differ by their differences, rational and irrational; which differences, however, do not differ from each other by other differences. Hence, to be quite accurate, it is better to say that they are, not different, but diverse. Hence, according to the Philosopher (Metaph. x), "things which are diverse are absolutely distinct, but things which are different differ by something." Therefore, strictly speaking, primary matter and God do not differ, but are by their very being, diverse. Hence it does not follow they are the same.


Having considered the divine simplicity, we treat next of God's perfection. Now because everything in so far as it is perfect is called good, we shall speak first of the divine perfection; secondly of the divine goodness.

Concerning the first there are three points of inquiry:

(1) Whether God is perfect?

(2) Whether God is perfect universally, as having in Himself the perfections of all things?

(3) Whether creatures can be said to be like God?

Whether God is perfect?

Objection: 1. It seems that perfection does not belong to God. For we say a thing is perfect if it is completely made. But it does not befit God to be made. Therefore He is not perfect.

2. Further, God is the first beginning of things. But the beginnings of things seem to be imperfect, as seed is the beginning of animal and vegetable life. Therefore God is imperfect.

3. Further, as shown above (Question [3], Article [4]), God's essence is existence. But existence seems most imperfect, since it is most universal and receptive of all modification. Therefore God is imperfect.

On the contrary It is written: "Be you perfect as also your heavenly Father is perfect" (Mt 5,48).

I answer that As the Philosopher relates (Metaph. xii), some ancient philosophers, namely, the Pythagoreans and Leucippus, did not predicate "best" and "most perfect" of the first principle. The reason was that the ancient philosophers considered only a material principle; and a material principle is most imperfect. For since matter as such is merely potential, the first material principle must be simply potential, and thus most imperfect. Now God is the first principle, not material, but in the order of efficient cause, which must be most perfect. For just as matter, as such, is merely potential, an agent, as such, is in the state of actuality. Hence, the first active principle must needs be most actual, and therefore most perfect; for a thing is perfect in proportion to its state of actuality, because we call that perfect which lacks nothing of the mode of its perfection.

Reply to Objection: 1. As Gregory says (Moral. v, 26,29): "Though our lips can only stammer, we yet chant the high things of God." For that which is not made is improperly called perfect. Nevertheless because created things are then called perfect, when from potentiality they are brought into actuality, this word "perfect" signifies whatever is not wanting in actuality, whether this be by way of perfection or not.

2. The material principle which with us is found to be imperfect, cannot be absolutely primal; but must be preceded by something perfect. For seed, though it be the principle of animal life reproduced through seed, has previous to it, the animal or plant from which is came. Because, previous to that which is potential, must be that which is actual; since a potential being can only be reduced into act by some being already actual.

3. Existence is the most perfect of all things, for it is compared to all things as that by which they are made actual; for nothing has actuality except so far as it exists. Hence existence is that which actuates all things, even their forms. Therefore it is not compared to other things as the receiver is to the received; but rather as the received to the receiver. When therefore I speak of the existence of man, or horse, or anything else, existence is considered a formal principle, and as something received; and not as that which exists.

Whether the perfections of all things are in God?

Objection: 1. It seems that the perfections of all things are not in God. For God is simple, as shown above (Question [3], Article [7]); whereas the perfections of things are many and diverse. Therefore the perfections of all things are not in God.

2. Further, opposites cannot coexist. Now the perfections of things are opposed to each other, for each thing is perfected by its specific difference. But the differences by which "genera" are divided, and "species" constituted, are opposed to each other. Therefore because opposites cannot coexist in the same subject, it seems that the perfections of all things are not in God.

3. Further, a living thing is more perfect than what merely exists; and an intelligent thing than what merely lives. Therefore life is more perfect than existence; and knowledge than life. But the essence of God is existence itself. Therefore He has not the perfections of life, and knowledge, and other similar perfections.

On the contrary Dionysius says (Div. Nom. v) that "God in His one existence prepossesses all things."

I answer that All created perfections are in God. Hence He is spoken of as universally perfect, because He lacks not (says the Commentator, Metaph. v) any excellence which may be found in any genus. This may be seen from two considerations. First, because whatever perfection exists in an effect must be found in the effective cause: either in the same formality, if it is a univocal agent---as when man reproduces man; or in a more eminent degree, if it is an equivocal agent---thus in the sun is the likeness of whatever is generated by the sun's power. Now it is plain that the effect pre-exists virtually in the efficient cause: and although to pre-exist in the potentiality of a material cause is to pre-exist in a more imperfect way, since matter as such is imperfect, and an agent as such is perfect; still to pre-exist virtually in the efficient cause is to pre-exist not in a more imperfect, but in a more perfect way. Since therefore God is the first effective cause of things, the perfections of all things must pre-exist in God in a more eminent way. Dionysius implies the same line of argument by saying of God (Div. Nom. v): "It is not that He is this and not that, but that He is all, as the cause of all." Secondly, from what has been already proved, God is existence itself, of itself subsistent (Question [3], Article [4]). Consequently, He must contain within Himself the whole perfection of being. For it is clear that if some hot thing has not the whole perfection of heat, this is because heat is not participated in its full perfection; but if this heat were self-subsisting, nothing of the virtue of heat would be wanting to it. Since therefore God is subsisting being itself, nothing of the perfection of being can be wanting to Him. Now all created perfections are included in the perfection of being; for things are perfect, precisely so far as they have being after some fashion. It follows therefore that the perfection of no one thing is wanting to God. This line of argument, too, is implied by Dionysius (Div. Nom. v), when he says that, "God exists not in any single mode, but embraces all being within Himself, absolutely, without limitation, uniformly;" and afterwards he adds that, "He is the very existence to subsisting things."

Reply to Objection: 1. Even as the sun (as Dionysius remarks, (Div. Nom. v)), while remaining one and shining uniformly, contains within itself first and uniformly the substances of sensible things, and many and diverse qualities; "a fortiori" should all things in a kind of natural unity pre-exist in the cause of all things; and thus things diverse and in themselves opposed to each other, pre-exist in God as one, without injury to His simplicity.

2. This suffices for the Reply to the Second Objection.

3. The same Dionysius says (Div. Nom. v) that, although existence is more perfect than life, and life than wisdom, if they are considered as distinguished in idea; nevertheless, a living thing is more perfect than what merely exists, because living things also exist and intelligent things both exist and live. Although therefore existence does not include life and wisdom, because that which participates in existence need not participate in every mode of existence; nevertheless God's existence includes in itself life and wisdom, because nothing of the perfection of being can be wanting to Him who is subsisting being itself.

Whether any creature can be like God?

Objection: 1. It seems that no creature can be like God. For it is written (Ps 85,8): "There is none among the gods like unto Thee, O Lord." But of all creatures the most excellent are those which are called participation gods. Therefore still less can other creatures be said to be like God.

2. Further, likeness implies comparison. But there can be no comparison between things in a different "genus." Therefore neither can there be any likeness. Thus we do not say that sweetness is like whiteness. But no creature is in the same "genus" as God: since God is no "genus," as shown above (Question [3], Article [5]). Therefore no creature is like God.

3. Further, we speak of those things as like which agree in form. But nothing can agree with God in form; for, save in God alone, essence and existence differ. Therefore no creature can be like to God.

4. Further, among like things there is mutual likeness; for like is like to like. If therefore any creature is like God, God will be like some creature, which is against what is said by Isaias: "To whom have you likened God?" (Is 40,18).

On the contrary It is written: "Let us make man to our image and likeness" (Gn 1,26), and: "When He shall appear we shall be like to Him" (1Jn 3,2).

I answer that Since likeness is based upon agreement or communication in form, it varies according to the many modes of communication in form. Some things are said to be like, which communicate in the same form according to the same formality, and according to the same mode; and these are said to be not merely like, but equal in their likeness; as two things equally white are said to be alike in whiteness; and this is the most perfect likeness. In another way, we speak of things as alike which communicate in form according to the same formality, though not according to the same measure, but according to more or less, as something less white is said to be like another thing more white; and this is imperfect likeness. In a third way some things are said to be alike which communicate in the same form, but not according to the same formality; as we see in non-univocal agents. For since every agent reproduces itself so far as it is an agent, and everything acts according to the manner of its form, the effect must in some way resemble the form of the agent. If therefore the agent is contained in the same species as its effect, there will be a likeness in form between that which makes and that which is made, according to the same formality of the species; as man reproduces man. If, however, the agent and its effect are not contained in the same species, there will be a likeness, but not according to the formality of the same species; as things generated by the sun's heat may be in some sort spoken of as like the sun, not as though they received the form of the sun in its specific likeness, but in its generic likeness. Therefore if there is an agent not contained in any "genus," its effect will still more distantly reproduce the form of the agent, not, that is, so as to participate in the likeness of the agent's form according to the same specific or generic formality, but only according to some sort of analogy; as existence is common to all. In this way all created things, so far as they are beings, are like God as the first and universal principle of all being.

Reply to Objection: 1. As Dionysius says (Div. Nom. ix), when Holy Writ declares that nothing is like God, it does not mean to deny all likeness to Him. For, "the same things can be like and unlike to God: like, according as they imitate Him, as far as He, Who is not perfectly imitable, can be imitated; unlike according as they fall short of their cause," not merely in intensity and remission, as that which is less white falls short of that which is more white; but because they are not in agreement, specifically or generically.

2. God is not related to creatures as though belonging to a different "genus," but as transcending every "genus," and as the principle of all "genera."

3. Likeness of creatures to God is not affirmed on account of agreement in form according to the formality of the same genus or species, but solely according to analogy, inasmuch as God is essential being, whereas other things are beings by participation.

4. Although it may be admitted that creatures are in some sort like God, it must nowise be admitted that God is like creatures; because, as Dionysius says (Div. Nom. ix): "A mutual likeness may be found between things of the same order, but not between a cause and that which is caused." For, we say that a statue is like a man, but not conversely; so also a creature can be spoken of as in some sort like God; but not that God is like a creature.


We next consider goodness: First, goodness in general. Secondly, the goodness of God.

Under the first head there are six points of inquiry:

(1) Whether goodness and being are the same really?

(2) Granted that they differ only in idea, which is prior in thought?

(3) Granted that being is prior, whether every being is good?

(4) To what cause should goodness be reduced?

(5) Whether goodness consists in mode, species, and order?

(6) Whether goodness is divided into the virtuous, the useful, and the pleasant?

Whether goodness differs really from being?

Objection: 1. It seems that goodness differs really from being. For Boethius says (De Hebdom.): "I perceive that in nature the fact that things are good is one thing: that they are is another." Therefore goodness and being really differ.

2. Further, nothing can be its own form. "But that is called good which has the form of being", according to the commentary on De Causis. Therefore goodness differs really from being.
3. Further, goodness can be more or less. But being cannot be more or less. Therefore goodness differs really from being.

On the contrary Augustine says (De Doctr. Christ. i, 42) that, "inasmuch as we exist we are good."

I answer that Goodness and being are really the same, and differ only in idea; which is clear from the following argument. The essence of goodness consists in this, that it is in some way desirable. Hence the Philosopher says (Ethic. i): "Goodness is what all desire." Now it is clear that a thing is desirable only in so far as it is perfect; for all desire their own perfection. But everything is perfect so far as it is actual. Therefore it is clear that a thing is perfect so far as it exists; for it is existence that makes all things actual, as is clear from the foregoing (Question [3], Article [4]; Question [4], Article [1]). Hence it is clear that goodness and being are the same really. But goodness presents the aspect of desirableness, which being does not present.

Reply to Objection: 1. Although goodness and being are the same really, nevertheless since they differ in thought, they are not predicated of a thing absolutely in the same way. Since being properly signifies that something actually is, and actuality properly correlates to potentiality; a thing is, in consequence, said simply to have being, accordingly as it is primarily distinguished from that which is only in potentiality; and this is precisely each thing's substantial being. Hence by its substantial being, everything is said to have being simply; but by any further actuality it is said to have being relatively. Thus to be white implies relative being, for to be white does not take a thing out of simply potential being; because only a thing that actually has being can receive this mode of being. But goodness signifies perfection which is desirable; and consequently of ultimate perfection. Hence that which has ultimate perfection is said to be simply good; but that which has not the ultimate perfection it ought to have (although, in so far as it is at all actual, it has some perfection), is not said to be perfect simply nor good simply, but only relatively. In this way, therefore, viewed in its primal (i.e. substantial) being a thing is said to be simply, and to be good relatively (i.e. in so far as it has being) but viewed in its complete actuality, a thing is said to be relatively, and to be good simply. Hence the saying of Boethius (De Hebrom.), "I perceive that in nature the fact that things are good is one thing; that they are is another," is to be referred to a thing's goodness simply, and having being simply. Because, regarded in its primal actuality, a thing simply exists; and regarded in its complete actuality, it is good simply---in such sort that even in its primal actuality, it is in some sort good, and even in its complete actuality, it in some sort has being.

2. Goodness is a form so far as absolute goodness signifies complete actuality.

3. Again, goodness is spoken of as more or less according to a thing's superadded actuality, for example, as to knowledge or virtue.

Whether goodness is prior in idea to being?

Objection: 1. It seems that goodness is prior in idea to being. For names are arranged according to the arrangement of the things signified by the names. But Dionysius (Div. Nom. iii) assigned the first place, amongst the other names of God, to His goodness rather than to His being. Therefore in idea goodness is prior to being.

2. Further, that which is the more extensive is prior in idea. But goodness is more extensive than being, because, as Dionysius notes (Div. Nom. v), "goodness extends to things both existing and non-existing; whereas existence extends to existing things alone." Therefore goodness is in idea prior to being.

3. Further, what is the more universal is prior in idea. But goodness seems to be more universal than being, since goodness has the aspect of desirable; whereas to some non-existence is desirable; for it is said of Judas: "It were better for him, if that man had not been born" (Mt 26,24). Therefore in idea goodness is prior to being.

4. Further, not only is existence desirable, but life, knowledge, and many other things besides. Thus it seems that existence is a particular appetible, and goodness a universal appetible. Therefore, absolutely, goodness is prior in idea to being.

On the contrary It is said by Aristotle (De Causis) that "the first of created things is being."

I answer that In idea being is prior to goodness. For the meaning signified by the name of a thing is that which the mind conceives of the thing and intends by the word that stands for it. Therefore, that is prior in idea, which is first conceived by the intellect. Now the first thing conceived by the intellect is being; because everything is knowable only inasmuch as it is in actuality. Hence, being is the proper object of the intellect, and is primarily intelligible; as sound is that which is primarily audible. Therefore in idea being is prior to goodness.

Reply to Objection: 1. Dionysius discusses the Divine Names (Div. Nom. i, iii) as implying some causal relation in God; for we name God, as he says, from creatures, as a cause from its effects. But goodness, since it has the aspect of desirable, implies the idea of a final cause, the causality of which is first among causes, since an agent does not act except for some end; and by an agent matter is moved to its form. Hence the end is called the cause of causes. Thus goodness, as a cause, is prior to being, as is the end to the form. Therefore among the names signifying the divine causality, goodness precedes being. Again, according to the Platonists, who, through not distinguishing primary matter from privation, said that matter was non-being, goodness is more extensively participated than being; for primary matter participates in goodness as tending to it, for all seek their like; but it does not participate in being, since it is presumed to be non-being. Therefore Dionysius says that "goodness extends to non-existence" (Div. Nom. v).

2. The same solution is applied to this objection. Or it may be said that goodness extends to existing and non-existing things, not so far as it can be predicated of them, but so far as it can cause them---if, indeed, by non-existence we understand not simply those things which do not exist, but those which are potential, and not actual. For goodness has the aspect of the end, in which not only actual things find their completion, but also towards which tend even those things which are not actual, but merely potential. Now being implies the habitude of a formal cause only, either inherent or exemplar; and its causality does not extend save to those things which are actual.

3. Non-being is desirable, not of itself, but only relatively---i.e. inasmuch as the removal of an evil, which can only be removed by non-being, is desirable. Now the removal of an evil cannot be desirable, except so far as this evil deprives a thing of some being. Therefore being is desirable of itself; and non-being only relatively, inasmuch as one seeks some mode of being of which one cannot bear to be deprived; thus even non-being can be spoken of as relatively good.

4. Life, wisdom, and the like, are desirable only so far as they are actual. Hence, in each one of them some sort of being is desired. And thus nothing can be desired except being; and consequently nothing is good except being.

Summa Th. I EN Qu.3 a.5