The Holy Trinity

Author: St. Thomas Aquinas


Saint Thomas Aquinas

Excerpt from: LIGHT OF FAITH, The Compendium of Theology

36Philosophical character of this doctrine

The truths about God thus far proposed have been subtly discussed by a number of pagan philosophers, although some of them erred concerning these matters. And those who propounded true doctrine in this respect were scarcely able to arrive at such truths even after long and painstaking investigation.

But there are other truths about God revealed to us in the teaching of the Christian religion, which were beyond the reach of the philosophers. These are truths about which we are instructed, in accord with the norm of Christian faith, in a way that transcends human perception.

The teaching is that although God is one and simple, as has been explained above,42 God is Father, God is Son, and God is Holy Spirit. And these three are not three gods, but are one God. We now turn to a consideration of this truth, so far as is possible to us.

37The Word in God

We take from the doctrine previously laid down that God understands and loves Himself, likewise, that understanding and willing in Him are not something distinct from His essence. Since God understands Himself, and since all that is understood is in the person who understands, God must be in Himself as the object understood is in the person understanding.

But the object understood, so far as it is in the one who understands, is a certain word of the intellect. We signify by an exterior word what we comprehend interiorly in our intellect. For words, according to the Philosopher, are signs of intellectual concepts.43 Hence we must acknowledge in God the existence of His Word.

38 The word as conception

What is contained in the intellect, as an interior word, is by common usage said to be a conception of the intellect. A being is said to be conceived in a corporeal way if it is formed in the womb of a living animal by a life-giving energy, in virtue of the active function of the male and the passive function of the female in whom the conception takes place. The being thus conceived shares in the nature of both parents and resembles them in species.

In a similar manner, what the intellect comprehends is formed in the intellect, the intelligible object being, as it were, the active principle, and the intellect the passive principle. That which is

thus comprehended by the intellect, existing as it does within the intellect, is conformed both to the moving intelligible object (of which it is a certain likeness) and to the quasi-passive intellect (which confers on it intelligible existence). Hence what is comprehended by the intellect is not unfittingly called the conception of the intellect.

39Relation of the Word to the Father

But here a point of difference must be noted. What is conceived in the intellect is a likeness of the thing understood and represents its species; and so it seems to be a sort of offspring of the intellect. Therefore, when the intellect understands something other than itself, the thing understood is, so to speak, the father of the word conceived in the intellect, and the intellect itself resembles rather a mother, whose function is such that conception takes place in her. But when the intellect understands itself, the word conceived is related to the understanding person as offspring to father. Consequently, since we are using the term word in the latter sense (that is, according as God understands Himself), the word itself must be related to God, from whom the word proceeds, as Son to Father.

40Generation in God

Hence in the rule of the Catholic Faith we are taught to profess belief in the Father and Son in God by saying: "I believe in God the Father, and in His Son." And lest anyone, on hearing Father and Son mentioned, should have any notion of carnal generation, by which among us men father and son receive their designation, John the Evangelist, to whom were revealed heavenly mysteries, substitutes Word for Son,44 so that we may understand that the generation is intellectual.

41 The Son is equal to the Father in existence and essence

Since natural existence and the action of understanding are distinct in us, we should note that a word conceived in our intellect, having only intellectual existence, differs in nature from our intellect, which has natural existence. In God, however, to be and to understand are identical. Therefore, the divine Word that is in God, whose Word He is according to intellectual existence, has the same existence as God, whose Word He is. Consequently the Word must be of the same essence and nature as God Himself, and all attributes whatsoever that are predicated of God, must pertain also to the Word of God.

42 This teaching in the Catholic Faith

Hence we are instructed in the rule of the Catholic Faith to profess that the Son is "consubstantial with the Father," a phrase that excludes two errors. First, the Father and the Son may not be thought of according to carnal generation, which is effected by a certain separation of the son's substance from the father. If this were so in God, the Son could not be consubstantial with the Father. Secondly, we are taught not to think of the Father and the Son according to intellectual generation in the way that a word is conceived in our mind. For such a word comes to our intellect by a sort of accidental accretion, and does not exist with the existence proper to the essence of the intellect.

43 The Word is not distinct from the Father in arm, species, or nature

Among things that are not distinct in essence, there can be no distinction according to species, time, or nature. Therefore, since the Word is consubstantial with the Father, He cannot differ from the Father in any of these respects.

There can be no difference according to time. The divine Word is present in God for the reason that God understands Himself, thereby conceiving His intelligible Word. Hence, if at any time there were no Word of God, during that period God would not understand Himself. But God always understood Himself during His whole existence, because His understanding is His existence. Therefore His Word, also, existed always. And so in the rule of the Catholic Faith we say that the Son of God "is born of the Father before all ages."

According to species, too, it is impossible for the Word of God to differ from God, as though He were inferior; for God does not understand Himself to be less than He is. The Word has a perfect likeness to the Father, because that whereof He is the Word is perfectly understood. Therefore the Word of God must be absolutely perfect according to the species of divinity.

Some beings, it is true, that proceed from others, are found not to inherit the perfect species of those from whom they proceed. One way in which this can happen is in equivocal generations: the sun does not generate a sun, but an animal of some kind.45 In order to exclude imperfection of this sort from divine generation, we proclaim that the Word is born "God from God."

The same thing occurs in another way when that which proceeds from another differs from the latter because of a defect in purity; that is, when something is produced from what is simple and pure in itself by being applied to extraneous matter, and so turns out to be inferior to the original species. Thus, from a house that is in the architect's mind, a house is fashioned in various materials; and from light received in the surface of a body, color results; and from fire, by adding other elements, a mixture is produced; and from a beam of light, by interposing an opaque body, shadow is caused. To exclude any imperfection of this kind from divine generation, we add: "Light from Light."

In yet a third way, what proceeds from another can fail to equal the latter's species, because of a deficiency in truth. That is, it does not truly receive the nature of its original, but only a certain likeness thereof (for example, an image in a mirror or in a picture or in a statue; also, the likeness of a thing in the intellect or in one of the senses). For the image of a man is not said to be a true man, but is a likeness of a man; and a stone is not in the soul, as the Philosopher notes, but a likeness of the stone is in the soul.46 To exclude all this from divine generation, we subjoin: "True God from true God."

Lastly it is impossible for the Word to differ from God according to nature, since it is natural for God to understand Himself Every intellect has some objects which it naturally understands. Thus, our intellect naturally understands first principles. Much more does God, whose intellectual activity is His existence, naturally understand Himself.

Therefore His Word proceeds from Him naturally, not in the way that things proceed otherwise than by natural origin (that is, not in the way that artificial objects, which we are said to make, take shape from us). On the other hand, whatever proceeds from us naturally we are said to generate (for example, a son). Accordingly, to preclude the error of thinking that the Word of God proceeds from God, not by way of nature, but by the power of His will, the phrase is added: "begotten, not made."

44Conclusion from the foregoing

As is clear from the foregoing, all the characteristics of divine generation we have been discussing lead to the conclusion that the Son is consubstantial with the Father. Therefore, by way of summing up all these points, the words, "consubstantial with the Father," are subjoined.

45God in Himself as beloved in lover

As the object known is in the knower to the extent that it is known, so the beloved must be in the lover, as loved. The lover is, in some way, moved by the beloved with a certain interior impulse.

Therefore, since a mover is in contact with the object moved the beloved must be intrinsic to the lover. But God, just as He understands Himself, must likewise love Himself; for good, as apprehended, is in itself lovable. Consequently God is in Himself as beloved in lover.

46Love in God as Spirit

Since the object known is in the knower and the beloved is in the lover, the different ways of existing in something must be considered in the two cases before us. The act of understanding takes place by a certain assimilation of the knower to the object known; and so the object known must be in the knower in the sense that a likeness of it is present in him.

But the act of loving takes place through a sort of impulse engendered in the lover by the beloved: the beloved draws the lover to himself. Accordingly, the act of loving reaches its perfection not in a likeness of the beloved (in the way that the act of understanding reaches perfection in a likeness of the object understood); rather the act of loving reaches its perfection in a drawing of the lover to the beloved in person.

The transferring of the likeness of the original is effected by univocal generation whereby, among living beings, the begetter is called father, and the begotten is called son. Among such beings, moreover, the first motion occurs conformably to the species. Therefore, as within the Godhead the way whereby God is in God as the known in the knower, is expressed by what we call Son, who is the Word of God, so the way by which God is in God as the beloved is in the lover is brought out by acknowledging in God a Spirit, who is the love of God. And so, according to the rule of the Catholic Faith, we are directed to believe in the Spirit.

47Holiness of the Spirit in God

Another point to consider is this. Since good that is loved has the nature of an end, and since the motion of the will is designated good or evil in terms of the end it pursues, the love whereby the supreme good that is God is loved must possess the supereminent goodness that goes by the name of holiness. This is true whether holy is taken as equivalent to "pure," according to the Greeks (the idea being that in God there is purest goodness free from all defect) or whether holy is taken to mean "firm," in the view of the Latins (on the score that in God there is unchangeable goodness). In either case, everything dedicated to God is called holy, such as a temple and the vessels of the temple and all objects consecrated to divine service. Rightly, then, the Spirit, who represents to us the love whereby God loves Himself, is called the Holy Spirit. For this reason the rule of the Catholic Faith proclaims that the Spirit is holy, in the clause, "I believe in the Holy Spirit."

48 Love in God is not accidental

Just as God's understanding is His existence, so likewise is His love. Accordingly, God does not love Himself by any act that is over and above His essence; He loves Himself by His very essence. Since God loves Himself because He is in Himself as the beloved in the lover, God the beloved is not in God the lover in any accidental fashion (in the way that the objects of our love are in us who love them - that is, accidentally). No, God is substantially in Himself as beloved in lover. Therefore the Holy Spirit, who represents the divine love to us, is not something accidental in God, but subsists in the divine essence just as the Father and the Son do. And so in the rule Of the Catholic Faith He is exhibited as no less worthy of adoration and glorification than the Father and the Son are.

49 Procession of the Holy Spirit from the Father and the Son

We should recall that the act of understanding proceeds from the intellectual power of the mind. When the intellect actually understands, the object it understands is in it. The presence of the object known in the knower results from the intellectual power of the mind, and is its word, as we said above.47 Likewise, what is loved is in the lover, when it is actually loved. The fact that an object is actually loved, results from the lover's power to love and also from the lovable good as actually known. Accordingly, the presence of the beloved object in the lover is brought about by two factors: the appetitive principle and the intelligible object as apprehended (that is, the word conceived about the lovable object). Therefore, since the Word in God who knows and loves Himself is the Son, and since He to whom the Word belongs is the Father of the Word, as is clear from our exposition, the necessary consequence is that the Holy Spirit, who pertains to the love whereby God is in Himself as beloved in lover, proceeds from the Father and the Son. And so we say in the Creed: "who proceeds from the Father and the Son."

50The Trinity of divine persons and the unity of the divine essence

We must conclude from all we have said that in the Godhead there is something threefold which is not opposed to the unity and simplicity of the divine essence. We must acknowledge that God is, as existing in His nature, and that He is known and loved by Himself.

But this occurs otherwise in God than in us. Man, to be sure, is a substance in his nature, but his actions of knowing and loving are not his substance. Considered in his nature, man is indeed a subsisting thing; as he exists in his mind, however, he is not a subsisting thing, but a certain representation of a subsisting thing; and similarly with regard to his existence in himself as beloved in lover. Thus man may be regarded under three aspects: that is, man existing in his nature, man existing in his intellect, and man existing in his love. Yet these three are not one, for man's knowing is not his existing, and the same is true of his loving. Only one of these three is a subsisting thing, namely, man existing in his nature.

In God, on the contrary, to be, to know, and to love are identical. Therefore God existing in His natural being and God existing in the divine intellect and God existing in the divine love are me thing. Yet each of them is subsistent. And, as things subsisting in intellectual nature are usually called persons in Latin, or hypostases in Greek, the Latins say that there are three persons in God, and the Greeks say that there are three hypostases, namely, the Father, the Son, and the Holy Spirit.

51A seeming contradiction in the Trinity

A certain contradiction, arising from truths previously established, seemingly appears at this point. If threefold personality is assumed in God, then, since number always follows division, some division will have to be acknowledged in God whereby the three may be distinguished from one another. Thus supreme simplicity will be lacking in God. If three agree in some respect and differ in another, composition must be present - which is contrary to what was set forth above.48 Again, if God must be strictly one, as has. been shown above,49 and if one and the same thing cannot originate or proceed from itself, it therefore seems impossible for God to be begotten or to proceed. Wrongly, therefore, the names of Father, Son, and proceeding Spirit are given place in the Godhead.

52Solution of the difficulty: distinction in God according to relations

The principle for solving this difficulty must be derived from the fact that, among different classes of beings, the various ways in which one thing may arise or proceed from another depend on the diversity of their natures. Among lifeless beings, which do not move themselves and are capable of being moved only from outside, one thing arises from another by being, as it were, outwardly altered and changed. In this way fire is generated from fire and air from air.

But among living beings (which have the property of moving themselves), something is generated within the parent (for example, the young of animals and the fruits of plants). Moreover, the different manner of procession in living beings must be viewed according to their different powers and their different kinds of proceeding.

Among such beings, there are certain powers whose operations extend only to bodies, so far as they are material. This is clear with regard to the powers of the vegetative soul, which serve nutrition, growth, and generation. In virtue of this class of the soul's powers, there proceeds only what is corporeal and what is bodily distinct although, in the case of living beings, it is somehow joined to that from which it proceeds.

There are other powers whose operations do not transcend the limits of bodies and yet extend to the species of bodies, receiving them without their accompanying matter. This is the case with all the powers of the sensitive soul. For sense is capable of receiving species without matter, as the Philosopher says.50 But such faculties, although they are receptive of the forms of things in a sort of immaterial way, do not receive them without a bodily organ. If procession takes place within these powers of the soul, that which proceeds will not be something corporeal, nor will it be distinct or joined to that faculty whence it proceeds in a corporeal way, but rather in a certain incorporeal and immaterial fashion, although not entirely without the help of a bodily organ.

Thus the representations of things imagined, which exist in the imagination not as a body in a body, but in a certain spiritual way, proceed in animals. This is why imaginary vision is called spiritual by Augustine.51

But if something proceeds in a way that is not corporeal when the imagination is in action, this will be the case much more in the operation of the intellectual faculty, which can act without any bodily organ at all; its operation is strictly immaterial. For in intellectual operation a word proceeds in such a way that it exists in the very intellect of the speaker, not as though contained therein locally, nor as bodily separated therefrom, but as present there in a manner that is conformable to its origin. The same is true in that procession which is observed to take place in the operation of the will, so far as the thing loved exists in the lover, in the sense described above.52 However, although the intellectual and sensitive powers are nobler in their own scale of being than the powers of the vegetative soul, nothing that subsists in the nature of the same species proceeds either in men or in other animals according to the procession of the imaginative or sensitive faculties. This occurs only in that procession which takes place through the operation of the vegetative soul.

The reason for this is that in all beings composed of matter and form, the multiplication of individuals in the same species is effected by a division of matter. Hence among men and other animals, composed as they are of form and matter, individuals are multiplied in the same species by the bodily division which ensues in the procession that is proper to the operation of the vegetative soul, but that does not take place in other operations of the soul. In beings that are not composed of matter and form, no distinction can be discerned other than that of the forms themselves. But if the form, which is the reason for the distinction, is the substance of a thing, the distinction must obtain between subsistent things. Of course, this is not the case if the form in question is not the substance of the thing.

As is clear from our discussion, every intellect has this in common, that what is conceived in the intellect must in some way proceed from the knower, so far as he is knowing; and in its procession it is to some extent distinct from him, just as the conception of the intellect, which is the intellectual likeness,53 is distinct from the knowing intellect. Similarly the affection of the lover, whereby the beloved is in the lover, must proceed from the will of the lover so far as he is loving. But the divine intellect has this exclusive perfection: since God's understanding is His existence, His intellectual conception, which is the intelligible likeness, must be His substance; and the case is similar with affection in God, regarded as loving. Consequently the representation of the divine intellect, which is God's Word, is distinct from Him who produces the Word, not with respect to substantial existence, but only according to the procession of one from the other. And in God considered as loving, the same is true of the affection of love, which pertains to the Spirit.

Thus it is plain that nothing prevents God's Word, who is the Son, from being one with the Father in substance, and that, nevertheless, the Word is distinct from the Father according to the relation of procession, as we have said. Hence it is also evident that the same thing does not arise or proceed from itself, for the Son, as proceeding from the Father, is distinct from Him. And the same observation holds true of the Holy Spirit, relative to the Father and the Son.

53 Nature of the relations whereby the Father, the Son, and the Holy Spirit are distinguished

The relations by which the Father, the Son, and the Holy Spirit are distinguished from one another are real relations, and not merely mental relations. Those relations are purely mental which do not correspond to anything found in the nature of things, but depend on intellectual apprehension alone. Thus right and left in a stone are not real relations, but only mental relations; they do not correspond to any real disposition present in the stone, but exist only in the mind of one who apprehends the stone as left, because it is, for instance, to the left of some animal. On the other hand, left and right in an animal are real relations, because they correspond to certain dispositions found in definite parts of the animal. Therefore, since the relations which distinguish the Father, the Son, and the Holy Spirit really exist in God, the relations in question must be real relations, and are not merely mental relations.

54 Relations in God are not accidental

These relations cannot inhere in God accidentally, because the operations on which the relations follow directly are the very substance of God, and also because, as was shown above,54 there can be no accident in God. Hence, if the relations are really in God, they cannot be accidentally inherent, but must be subsistent. How it is that what is an accident in other things, can exist substantially in God, is clear from the doctrine previously set forth.55

55Personal distinction in God through the relations

Since distinction in the Godhead is accounted for by relations that are not accidental but are subsistent, and since among beings subsisting in an intellectual nature personal distinction is discerned, it necessarily follows that personal distinction in God is constituted by the relations in question. Therefore the Father and the Son and the Holy Spirit are three persons, and also three hypostases, since hypostasis means "that which is subsistent and complete."

56Impossibility of more than three persons in God

There cannot be more than three persons in God. For the divine persons cannot be multiplied by a division of their substance, but solely by the relation of some procession; and not by any sort of procession, but only by such as does not have its term in something outside of God. If the relation had something external as its term, this would not possess the divine nature, and so could not be a divine person or hypostasis. But procession in God that does not terminate outside of God, must be either according to the operation of the intellect, whereby the Word proceeds, or according to the operation of the will, whereby love proceeds, as is clear from our exposition.56 Therefore no divine person can proceed unless He proceeds as the Word, whom we call the Son, or as love, whom we call the Holy Spirit.

Moreover, since God comprehends everything in His intellect by a single act of intuition and similarly loves everything by a single act of His will, there cannot be several words or several loves in God. If, then, the Son proceeds as Word, and if the Holy Spirit proceeds as love, there cannot be several Sons or several Holy Spirits in God.

Again: the perfect is that beyond which there is nothing. Hence a being that would tolerate anything of its own class to be outside itself, would fall short of absolute perfection. This is why things that are simply perfect in their natures are not numerically multiplied; thus God, the sun, the moon, and so on.57 But both the Son and the Holy Spirit must be simply perfect, since each of them is God, as we have shown.58 Therefore several Sons or several Holy Spirits are impossible.

Besides, that whereby a subsistent thing is this particular thing, distinct from other things, cannot be numerically multiplied, for the reason that an individual cannot be predicated of many. But the Son is this divine person, subsisting in Himself and distinct from the other divine persons by sonship just as Socrates is constituted this human person by individuating principles. Accordingly, as the individuating principles whereby Socrates is this man cannot pertain to more than one man, so sonship in the Godhead cannot pertain to more than one divine person. Similar is the case with the relation of the Father and the Holy Spirit. Hence there cannot be several Fathers in God or several Sons or several Holy Spirits.

Lastly, whatever is one by reason of its form, is not numerically multiplied except through matter (thus, whiteness is multiplied by existing in many subjects). But there is no matter in God. Consequently, whatever is one in species and form in the Godhead cannot be multiplied numerically. Such are paternity and filiation and the procession of the Holy Spirit. And thus there cannot be several Fathers or Sons or Holy Spirits in God.

57Properties of the Father

Such being the number of persons in God, the properties whereby the persons are distinguished from one another must be of some definite number. Three properties are characteristic of the Father. The first is that whereby He is distinguished from the Son alone. This is paternity. The second is that whereby the Father is distinguished from the other two persons, namely, the Son and the Holy Spirit. And this is innascibility; for the Father is not God as proceeding from another person, whereas the Son and the Holy Spirit do proceed from another person. The third property is that whereby the Father along with the Son is distinguished from the Holy Spirit. This is called their common spiration. But a property whereby the Father may be distinguished from the Holy Spirit alone is not to be assigned, for the reason that the Father and the Son are a single principle of the Holy Spirit, as has been shown.59

58Properties of the Son and the Holy Spirit

Two properties must pertain to the Son: one whereby He is distinguished from the Father, and this is filiation; another whereby, along with the Father, He is distinguished from the Holy Spirit; and this is their common spiration. But no property is to be assigned whereby the Son is distinguished from the Holy Spirit alone, because, as we said above, the Son and the Father are a single principle of the Holy Spirit.60 Similarly, no single property is to be assigned whereby the Holy Spirit and the Son together are distinguished from the Father. For the Father is distinguished from them by one property, namely, innascibility, inasmuch as He does not proceed. However, since the Son and the Holy Spirit proceed, not by one procession, but by several, they are distinguished from the Father by two properties. The Holy Spirit has only one property by which He is distinguished from the Father and the Son, and this is called procession. That there cannot be any property by which the Holy Spirit may be distinguished from the Son alone or from the Father alone, is evident from this whole discussion.

Accordingly, five properties in all are attributed to the divine persons: innascibility, paternity, filiation, spiration, and procession.

59Why these properties are called notions

These five properties can be called notions of the persons, for the reason that the distinction between the persons in God is brought to our notice through them. On the other hand, they cannot be called properties, if the root meaning of property is insisted on, so that property is taken to mean a characteristic pertaining to one individual alone, for common spiration pertains to the Father and the Son.

But if the word property is employed in the sense of an attribute that is proper to some individuals as setting them off from others (in the way that two-footed, for example, is proper to man and bird in contradistinction to quadrupeds), there is nothing to prevent even common spiration from being called a property. Since, however, the persons in God are distinguished solely by relations, and distinction among the divine persons is manifested by the notions, the notions must in some sense pertain to relationship.

But only four of the notions are real relations, whereby the divine persons are related to one another. The fifth notion, innascibility, pertains to relation as being the denial of relation (for negations are reduced to the genus of affirmations, and privations are reduced to the genus of habits, as, for example, not man is reduced to the genus of man, and not white is reduced to the genus of whiteness).61

We should note that among the relations whereby the divine persons are related to one another, some have definite names, such as paternity and filiation, which properly signify relationship. But others lack a definite name: those whereby the Father and the Son are related to the Holy Spirit, and the Holy Spirit is related to them. So for these we use names of origin in place of relative names.

We perceive clearly that common spiration and procession, signify origin, but not relations that follow origin. This can be brought out in the case of the relations between the Father and the Son. Generation denotes active origin, and is followed by the relation of paternity; and nativity signifies the passive generation of the Son, and is followed by the relation of filiation. In like mariner, some relation follows common spiration, and the same is true of procession. But as these relations lack definite names, we use the names of the actions instead of relative names.

60The number of relations and the number of persons

We must realize that, although the relations subsisting in the Godhead are the divine persons themselves, as was shown above,62 we are not therefore to conclude that there are five or four persons corresponding to the number of relations. For number follows distinction of some sort. Just as unity is indivisible or undivided, so plurality is divisible or divided. For a plurality of persons requires that relations have power to distinguish by reason of opposition, since formal distinction necessarily entails opposition. If, then, the relations in question are closely examined, paternity and filiation will be seen to have relative opposition to each other; hence they are incompatible in the same suppositum. Consequently paternity and filiation in God must be two subsistent persons. Innascibility, on the other hand, although opposed to filiation, is not opposed to paternity. Hence paternity and innascibility can pertain to one and the same person. Similarly, common spiration is not opposed either to paternity or to filiation, nor to innascibility. Thus nothing prevents common spiration from being in both the person of the Father and the person of the Son.

So common spiration is not a subsisting person distinct from the persons of the Father and the Son. But procession has a relation of opposition to common spiration. Therefore, since common spiration pertains to the Father and the Son, procession must be a person distinct from the persons of the Father and the Son.

Accordingly, the reason is clear why God is not called quiune (quinus) on account of the notions, which are five in number, but is called triune, on account of the Trinity of persons. The five notions are not five subsisting things, but the three persons are three subsisting things.

Although several notions or properties may pertain to a single person, only one of them constitutes the person. For a divine person is constituted by the properties, not in the sense that He is constituted by several of them, but in the sense that the relative, subsisting property itself is a person. If several properties were understood as subsisting in themselves apart, they would be several persons, and not one person. Hence we must understand that, of the several properties or notions belonging to a single person, the one that precedes63 according to the order of nature constitutes the person; the others are understood as inhering in the person already constituted.

Thus it is evident that innascibility cannot be the first notion of the Father, constituting His person, because nothing is constituted by a negation, and also because affirmation naturally precedes negation. Further, common spiration presupposes paternity and filiation in the order of nature, just as the procession of love presupposes the procession of the Word.

Hence common spiration cannot be the first notion of the Father or of the Son either. The first notion of the Father is paternity and the first notion of the Son is filiation, whereas procession alone is the notion of the Holy Spirit.

Accordingly, the notions constituting persons are three in number: paternity, filiation, and procession. And these notions must be strict properties. For that which constitutes a person must pertain to that person alone; individuating principles cannot belong to several individuals. Therefore, the three notions in question are called personal properties, in the sense that they constitute the three persons in the manner described. The remaining notions are called properties or notions of the persons, but not personal properties or notions, since they do not constitute a person.

61 Dependence of the hypostases on the personal properties

This makes it clear that if we were to remove the personal properties by intellectual abstraction, the hypostases could not remain. If a form is removed by intellectual abstraction, the subject of the form remains. Thus if whiteness is removed, the surface remains; if the surface is removed, the substance remains; if the form of the substance is removed, prime matter remains. But if the subject is removed, nothing remains.

In the case of God, the personal properties are the subsisting persons themselves. They do not constitute the persons in the sense that they are added to preexisting supposita; for in the Godhead nothing predicated absolutely, but only what is relative, can be distinct. So if the personal properties are removed by intellectual abstraction, no distinct hypostases remain. But if non-personal notions are thus removed, distinct hypostases do remain.

62 Effect of intellectual removal of personal properties

If the question were to be asked whether, in consequence of the removal of the personal properties by intellectual abstraction, the divine essence would remain, the answer is that in one respect it would remain, but in another it would not. Intellectual abstraction can take place in two ways. The first is by abstracting form from matter. In this abstraction the mind proceeds from the more formal to the more material; the first subject remains until the end, and the ultimate form is removed first. The second way of abstracting is by the abstraction of the universal from the particular, and this proceeds according to an order that is, in a sense, the opposite; the individuating material conditions are first removed, so that what is common may be retained.

In God, of course, there are neither matter and form, nor universal and particular. Nevertheless there is in the Godhead something that is common, and something that is proper and that supposes the common nature. In our human way of thinking, the divine persons are to the divine essence what individual supposita are to a common nature. According to the first type of intellectual abstraction, therefore, if we remove the personal properties, which are the subsisting persons themselves, the common nature does not remain. But in the second type of abstraction it does remain.

63Personal acts and personal properties

We can perceive from this discussion the nature of the order between the personal acts and the personal properties. The personal properties are subsistent persons. But a person subsisting in any nature whatsoever, acts in virtue of his nature when he communicates his nature; for the form of a species is the principle for generating a product that is of like species. Consequently, since personal acts in God have to do with communicating the divine nature, a subsisting person must communicate the common nature in virtue of the nature itself.

Two conclusions follow from this. The first is, that the generative power of the Father is the divine nature itself, for the power of performing any action is the principle in virtue of which a thing acts. The second conclusion is that, according to our way of conceiving, the personal act of generation presupposes both the divine nature and the personal property of the Father, which is the very hypostasis of the Father. This is true even though such property, regarded as a relation, follows from the act. Thus, in speaking of the Father, if we attend to the fact that He is a subsistent person, we can say that He generates because He is the Father. But if we are thinking of what pertains to relationship, it seems we should say, contrariwise, that He is the Father because He generates.

64 Generation with respect to the Father and with respect to the Son

However, we should see that the order of active generation (with reference to paternity) is to be taken one way and the order of passive generation or nativity (with reference to filiation) is to be taken another. In the order of nature, active generation presupposes the person of the begetter. But in the same order, passive generation, or nativity, precedes the begotten person, for the begotten person owes his existence to his birth. Thus active generation, according to our way of representing it, presupposes paternity, understood as constituting the person of the Father. Nativity, however, does not presuppose filiation, understood as constituting the person of the Son but, according to our manner of conceiving, precedes it in both respects, that is, both as being constitutive of the person and as being a relation. And whatever pertains to the procession of the Holy Spirit is to be understood in a similar way.

65Nature of the distinction between notional acts and notional properties

In thus indicating the order between notional acts and notional properties, we do not mean to imply that notional acts differ from personal properties in objective reality: they are distinct only according to our manner of conceiving. Just as God's act of understanding is God Himself understanding, so the Father's act of begetting is the begetting Father, although the modes of signifying are different. Likewise, although one divine person may have several notions, there is no composition in Him. Innascibility cannot cause any composition, since it is a negative property. And the two relations in the person of the Father (paternity and common spiration) are in reality identical as referring to the person of the Father; for, as the paternity is the Father, so common spiration in the Father is the Father, and in the Son is the Son. But these two properties differ according to the terms to which they refer; for by paternity the Father is related to the Son, and by common spiration He is related to the Holy Spirit. Likewise, the Son is related to the Father by filiation and to the Holy Spirit by common spiration.

66Identity between the relative properties and the divine essence

The relative properties must be the divine essence itself. For the relative properties are precisely the subsistent persons. But a person subsisting in the Godhead cannot be something other than the divine essence; and the divine essence is God Himself, as was shown above.64 Therefore the relative properties are in all reality identical with the divine essence.

Moreover, whatever is in a being besides its essence, is in it accidentally. But there cannot be any accidents in God, as was pointed out above.65 Accordingly, the relative properties are not really distinct from the divine essence.

67The divine properties are not externally affixed

The view proposed by Gilbert de la Porree66 and some of his followers, that the properties under discussion are not in the persons, but are external to them, cannot be defended. Real relations must be in the things that are related. This is evident in the case of creatures, for real relations are in them as accidents in their subjects. But the relations whereby the three persons are distinguished within the Godhead are real relations, as was demonstrated above.67 Hence they must be in the divine persons, but not, of course, as accidents. Other perfections, too, which in creatures are accidents, cease to be accidents when transferred to God, as was shown above.68 Such are wisdom, justice, and the like.

Besides, there can be no distinction in God except through the relations; all perfections that are predicated absolutely are common. Therefore, if the relations were external to the persons, no distinction would remain among the persons themselves. And so there are relative properties in the persons; but they are the persons themselves, and also the divine essence itself. In the same way wisdom and goodness are said to be in God, and are God Himself, as well as the divine essence, as was said above.69


42. Cf. chaps. 9, 15.
43. Aristotle, De interpretatione, I, 1 (16 a 3).
44. John 1:14
45. Ancient and medieval Philosophers commonly admitted the possibility of "equivocal generation," according to which some organisms were thought to be produced from inorganic matter, especially such as had previously been alive, under the influence of heavenly bodies, which were believed to be of a superior nature. Thus St. Thomas, Summa, Ia, q. 71, a. un.: "In the natural generation of animals begotten of seed, the active principle is the formative power that is in the seed; but in animals generated from putrefaction, the formative power is the influence of a heavenly body"; Ia., q. 91, a.2 ad 2: "The power of a heavenly body may cooperate in the work of natural generation, as the Philosopher says: 'Man is begotten from matter by man, and by the sun as well' (Aristotle, Phys., II, 2 [194 b 131]). ... But the power of the heavenly bodies suffices for the generation of certain imperfect animals from property disposed matter."
46. Aristotle, De anima, III, 8 (431 b 29).
47. Cf chap. 3 7.
48. Cf chap. 9.
49. Cf chap. 15.
50. Aristotle, De anima, 111, 4 (429 b 21).
51. De Genesi ad litteram, XII, vii, 16; xxiv, 50 (PL, XXXIV, 459, 474).
52. Cf chap. 46.
53. The term here used by St. Thomas, intentio intellecta, cannot well be translated literally. For our purposes we may translate it as "intellectual likeness," as "intellectual representation," or as "mental word." Regardless, the meaning itself is clear, for St. Thomas defines the term in his Summa Contra Gentiles, IV, 11: "Dico autem intentionem intellectam id quod intellectus in seipso concipit de re intellecta"; that is: "By intentio intellecta I mean that which the intellect conceives within itself of the thing understood."
54. Cf chap. 23.
55. Cf, e.g., chaps. 4, 6, 9-11, 2 1.
56. Cf. chaps. 3 7, 46.
57. St. Thomas and the Scholastics of his time thought that the stars were incorruptible and were constructed of matter essentially different from the matter of terrestrial bodies. Consequently the sun, the moon, and all the stars were held to be superior to the material objects of our Earth.
58. Cf. chap. 50.
59. Cf. chap. 49.
60. Cf chap. 49.
61. In connection with these two examples, see the better statement in the Summa, Ia, q. 33, a. 4 ad 3: 'Negation is reduced to the genus of affirmation, just as not man is reduced to the genus of substance, and not white to the genus of quality."
62 Cf. chaps. 54,55.
63 The context requires the reading praecedit instead of procedit (which is found in the Vives and the Mandonnet editions)
64. Cf. chap. 10.
65. Cf. chap. 23.
66. See Gilbert's commentaries, In librum de Trinitate (PL, LXIV, 1292) and In librum de praedicatione trium personarum (PL, LXIV, 1309). Gilbert retracted his error at the Council of Reims in 1148, as St. Bernard relates, In Cantica, serm. LXXX (PL, CLXXXIII, 1170). Cf. Denz., 389, 391.
67. Cf. chap. 53.
68. Cf. chap. 23.
69 Cf. chaps. 10, 22.

The above excerpt of Chapter 36, pages 35-62 is taken with permission from: Saint Thomas Aquinas. Light of Faith, The Compendium of Theology.
(Sophia Institute Press, 1993, softcover, 366 pgs)

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