Article 9 — Whether in God there are only three persons, or more or fewer than three

The ninth point of inquiry is whether in God there are only three persons, or more or fewer than three. (Parallel texts: ST I.30.2; I.31.1; In I Sent. 24.2.2; SCG IV.26; In II Sent. 10.5; 33.2, ad 1; Compendium theologiae, cc. 56, 60.)

It would seem that there are more than three.

Obj. 1: For Augustine says, in Against Maximinus: the Son did not beget a creator, not that he was unable but because there was no need to do so. (Augustine, Against Maximinus 2.12, para. 3 (PL 42:763).) Now, in God, just as in all perpetual things, there is no difference between being and being able. (Aristotle, Physics 3.7, 207b15–20.) Therefore, the Son did beget another Son; and thus, there are two Sons in God, and consequently more than three persons.

Obj. 2: To this it may be replied that the words he was not unable mean that it was not due to his lack of power.

On the contrary, the acts belonging to some nature are appropriate to every supposit of that nature, except on account of a lack of its power. Now, generation is an act pertaining to the perfection of the divine nature; otherwise it would not be appropriate to the Father, in whom there is nothing that is not perfect. If, then, the Son does not beget another Son, this will be because of a lack of power in him.

Obj. 3: If the Son cannot beget, he can be begotten, and therefore he has the power to be begotten but not the power to beget. Now, to beget differs from being begotten. Therefore, since powers are distinguished in reference to their objects, the Father’s power will not be the same as the Son’s, which is heretical.

Obj. 4: In things that are acting and being acted upon, the action and the passion are traced back to different principles; for in created things, a thing acts by reason of its form and is acted upon by reason of its matter. Now, to beget and to be begotten are signified by the mode of action and passion. Therefore, they must be referred to diverse principles, and thus there cannot be one power whereby the Father begets and the Son is begotten.

Obj. 5: But to this it might be replied that it is the same power, inasmuch as on either hand it is rooted in the divine essence, which is one in Father and Son.

On the contrary, the power to heat and the power to dry are rooted in one subject, namely, fire; and yet they are not one and the same power, for heat, which is the principle of heating, is a distinct quality from dryness, which is the principle of desiccation. Wherefore, the unity of the divine essence does not suffice to make one the Father’s power to beget and the Son’s power to be begotten.

Obj. 6: Everyone wise and intelligent has a concept due to his wisdom. Now, the Son is wise and intelligent just as the Father is. Therefore, he has a concept. But the Father’s concept is the Word, which is the Son. Therefore, the Son also has a Son.

Obj. 7: To this it may be replied that “word” is predicated of God not only personally but also essentially, and thus, the Word predicated essentially may be the Son’s concept.

On the contrary, “word” signifies a species conceived and ordered to manifestation, and thus, it indicates an origin. Now, those terms that indicate origin in God are predicated personally and not essentially. Therefore, “word” cannot be predicated essentially.

Obj. 8: Anselm says in the Monologion that as the Father speaks himself, so do the Son and the Holy Spirit. (Anselm of Canterbury, Monologion 62–63 (PL 158:207–10).) Now, as he says, for the Father to speak himself is the same as to beget a Son. Therefore, the Son begets another Son; and thus, the same conclusion follows.

Obj. 9: God is proved to beget from the fact that he bestows begetting on others: shall I that give generation to others be barren? says the Lord (Isa 66:9). Now, as the Father gives generation so too does the Son, because the works of the Trinity are undivided. Therefore, the Son begets a Son.

Obj. 10: Augustine says, in To Orosius, that the Father begets the Son by nature; (Augustine, Dialogue of 65 Questions, q. 7 (PL 40:736–37).) and Damascene says that generation is a work of nature. (John Damascene, On the Orthodox Faith 2.27 (PG 94:959–62).) Now, the Father and the Son have the same nature. Therefore, as the Father begets, so also does the Son; and consequently in God there are several Sons and more than three persons.

Obj. 11: But someone will reply that there cannot be more than one Son in God, since there can be but one filiation; for the form of one species is not multiplied otherwise than by division of matter, and there is no such thing in God.

On the contrary, any difference whatsoever is naturally apt to make a plurality. Now, there can be a difference between two filiations not only due to matter but also because this filiation is such and that filiation is such. Therefore, nothing prevents several filiations being in God, although there is no matter in him.

Obj. 12: The Son proceeds from the Father as brilliance from the sun, according to Hebrews 1:3, being the brilliance of his glory. Now, one brilliance can produce another brilliance. Therefore, the Son can beget another Son; and thus, there would be several Sons in God and more than three persons.

Obj. 13: The Holy Spirit is the love whereby the Father loves the Son. Now, the Father also loves the Holy Spirit. Therefore, there must be another Spirit whereby the Father loves the Holy Spirit; and thus, there will be four persons in God.

Obj. 14: According to Dionysius, the good is self-communicative. (Pseudo-Dionysius, The Divine Names 4.1, 4.7 (PG 3:693–96; 701–4).) Now, goodness is appropriated to the Holy Spirit, as is power to the Father and wisdom to the Son. Therefore, it seems to pertain most properly to the Holy Spirit that he should communicate the divine nature to another person; and thus, there will be more than three persons in God.

Obj. 15: According to the Philosopher in Meteorology 4, a thing is perfect when it can of itself produce its like. (Aristotle, Meteorology 4.4, 380a26–b12; cf. On the Soul 2.4, 416b23–31.) Now, the Holy Spirit is perfect God. Therefore, he can produce another person: and consequently, etc.

Obj. 16: The Son does not receive the divine nature from the Father more perfectly than does the Holy Spirit. Now, the Son receives from the Father the divine nature not only passively (so to speak), as being begotten of him, but also actively, because he can communicate the same nature to another. Therefore, the Holy Spirit also can communicate the divine nature to another person.

Obj. 17: Whatsoever belongs to perfection in creatures must be attributed to God. Now, it pertains to perfection in created things to communicate nature, although the mode of communication has a certain imperfection in that it involves division or change in the generator. Therefore, to communicate the divine nature belongs to perfection in God and, consequently, it must be attributed to the Holy Spirit. Therefore, a person proceeds from the Holy Spirit; and thus, it follows that there are more than three persons in God.

Obj. 18: Just as the divine nature is a good in the Father, so also is paternity. Now, based on the fact that no good is possessed with pleasure without others sharing in it, some prove that in God there are several persons having the divine nature. Therefore, for the same reason there are several Fathers, and several Sons and several Holy Spirits in God: and consequently more than three persons.

Obj. 19: The Son and the Holy Spirit seem to be distinguished from each other in that the Son proceeds from the Father through the mode of the intellect as a Word, while the Holy Spirit proceeds through the mode of the will as Love. But there are other essential attributes besides the intellect and will, such as goodness, power, and so forth. Therefore, other persons proceed from the Father besides the Son and Holy Spirit.

Obj. 20: A procession of nature seems to differ from a procession of the intellect more than does a process of the will. For in created things the procession of the intellect is always accompanied by a procession of the will, since whatever understands something also wills something, whereas a procession of nature is not always accompanied by a procession of intellect, since not everything that can generate can understand. If, then, in God the person who proceeds through the mode of the will as Love is distinct from the person who proceeds through the mode of the intellect as Word, there will also be a person who proceeds through the mode of the intellect distinct from the person who proceeds through the mode of nature as Son. Hence, there will be three persons proceeding in God and one who does not proceed; and thus, there are four persons.

Obj. 21: In God, the persons are multiplied on account of the subsistent relations. Now, in God there are five relative notions—namely, paternity, filiation, procession, innascibility, and common spiration. Therefore, there are five persons in God.

Obj. 22: The relations that are attributed to God from eternity are not in creatures but in God. Now, whatsoever is in God is subsistent, since in him there is no accident. Therefore, all relations that belong to God from eternity are subsistent and consequently are persons. Now, such relations are infinite in number; for the ideas of created things are in God from eternity, and they are not mutually distinct except by their relation to the created things. Therefore, the persons in God are infinite in number.

On the contrary, it would seem that there are fewer than three.

Obj. 1: In one nature there is but one mode of communication of that nature; this is why, according to the Commentator, animals generated from seed are not of the same species as those engendered from putrefaction. (Averroes, Commentary on the Physics 7.4, 8.6.) Now, the divine nature is supremely one; wherefore, it can be communicated in one way only. Therefore, there cannot be more than two persons, one that communicates divinity by some mode, and another that receives the divine nature in that same mode.

Obj. 2: Hilary shows that the Son proceeds from the Father naturally because he is such as God is, but that creatures proceed from God voluntarily because they are such as he wills them to be, not such as he is. (Hilary of Poitiers, On Synods 24.58 (PL 10:520).) Now, the Holy Spirit, like the Son, is such as God the Father is. Therefore, the Holy Spirit, like the Son, proceeds from the Father naturally; and consequently, there is no distinction between the Holy Spirit and the Son based on the Son proceeding naturally and the Holy Spirit not.

Obj. 3: In God, will and intellect do not differ except merely according to account. Therefore, procession through the modes of nature, intellect, and will do not differ in God except in account alone. Therefore, if the Son and the Holy Spirit are distinguished through the one proceeding through the mode of nature or intellect and the other through the mode of will, they will not be distinct except according to account. Therefore they will not be two persons, since plurality of persons indicates a plurality of realities.

Obj. 4: The persons in God are distinct by relations of origin only. Now, two relations suffice to indicate origin, namely, one from whom, and one who is from the other. Therefore, there are but two persons in God.

Obj. 5: Every relation requires two extremes. Since, then, in God the persons are not distinct save according to the relations, it follows that in God there are either two relations, and consequently four persons, or one relation, and therefore only two persons.

On the contrary (1), it is manifest that there are but three persons in God from 1 John 5:7, there are three who bear witness in heaven: (Cf. q. 9, a. 4, obj. 1.) and if we ask “three what?” the Church replies: “three persons,” as Augustine says. (Augustine, On the Trinity 7.4 (PL 42:939–42).) Therefore, there are three persons in God.

Furthermore (2), for the perfection of divine goodness, happiness, and glory there must be true and perfect charity in God; for nothing is better or more perfect than charity, as Richard says in On the Trinity. (Richard of St. Victor, On the Trinity 3.2 (PL 196:916–17).) Now, there is no happiness without enjoyment, and this arises chiefly from charity: for as we read, nothing is sweeter than charity, nothing more enjoyable, the intellectual life affords no sweeter experience, or delight more exquisite, than the delights of charity. (Richard of St. Victor, On the Trinity 3.5 (PL 196:918–19).) And the perfection of glory consists in the splendor of perfect communication, which is effected by charity. However, true and perfect charity requires the threefold number of persons in God. For the love whereby a person loves himself alone is a defective love and is not true charity. But God cannot love supremely another who is not supremely lovable; and none is supremely lovable who is not supremely good. Hence, it is evident that true charity cannot be supreme in God if there be but one person in him. Nor can it be perfect if there be but two persons; since perfect charity demands that the lover wish that what he loves be equally loved by another. For it is a sign of great weakness to be unable to undergo the sharing of one’s love, whereas to be able to undergo it is a sign of great perfection: the more one is pleased to receive a thing, the greater our longing in seeking it, (Richard of St. Victor, On the Trinity 3.11 (PL 196:922).) as Richard says in the same book. In God, therefore, since there is perfection of goodness, happiness, and glory, there must be a Trinity of persons.

Furthermore (3), as goodness is self-communicative, the perfection of divine goodness requires that he communicate his perfections supremely. But if there were only one person in God, he would not communicate his goodness supremely, for he does not communicate himself supremely to created things; and if there were but two persons, the delights of mutual charity would not be communicated perfectly. Hence, there must be a second person to whom the divine goodness is perfectly communicated, and a third to whom the delights of divine charity are perfectly communicated.

Furthermore (4), according to Augustine in On the Trinity 8, three things are required for love: the lover, the beloved, and love itself. (Augustine, On the Trinity 8.10, 9.1–2 (PL 42:960–62).) Now, the two who love each other are the Father and the Son, and the love that is their mutual bond is the Holy Spirit. Therefore, there are three persons in God.

Furthermore (5), as Richard remarks in On the Trinity 5, in mankind it is to be observed that a person proceeds from persons in three ways: first, immediately only, as Eve from Adam; second, mediately only, as Enoch from Adam: third, both immediately and mediately, as Seth from Adam, immediately as his son, mediately as the son of Eve who proceeded from Adam. (Richard of St. Victor, On the Trinity 5.6 (PL 196:952–53).) Now, in God one person cannot proceed from another mediately only, since there would not be perfect equality. Hence, we must conclude that in God there is one person that does not proceed from another, namely, the Father, from whom two other persons proceed; one immediately only, namely, the Son; and the other both mediately and immediately, namely, the Holy Spirit, who proceeds from the Father and the Son. Therefore, there are three persons in God.

Furthermore (6), to both give and receive the fullness of divinity comes between giving and not receiving it, and receiving without giving it. Now, it belongs to the person of the Father to give the fullness of divinity without receiving it; and to receive the fullness of divinity without giving it belongs to the person of the Holy Spirit. Therefore, there must be a third person who both gives and receives the fullness of divinity, and this is the person of the Son. And thus, there are three persons in God.

I answer that according to the opinions of heretics, it is impossible to assign a definite number of persons in God.

For Arius took the Trinity of persons to mean that the Son and Holy Spirit are certain creatures, and Macedonius was of the same opinion in regard to the Holy Spirit. (Macedonius, bishop of Constantinople from 342–346 AD and then from 351–360 AD (d. 362 AD). He was a leader of a semi-Arian sect and denied the divinity of the Holy Spirit.) Now, the procession of created things from God is not necessarily limited to a certain number, seeing that the divine power, from its own infinity, surpasses every mode, species, and number of a creature. Wherefore, if God the Father omnipotent created two most excellent creatures, whom Arius said were the Son and Holy Spirit, there is no reason why he should not create others equal to them or even greater than they.

Sabellius, however, contended that the Father, Son, and Holy Spirit are distinguished only in name and account, which also clearly can be multiplied to infinity, inasmuch as our reason can think about God in an infinity of ways based on his various effects and can give him various names.

However, only the Catholic faith, which asserts the unity of the divine nature in persons really distinct, can assign a reason for the Trinity in the divine. For it is impossible that the one simple nature be in more than one as in a principle. Wherefore Hilary says that whosoever acknowledges two innascibles in God must acknowledge two gods. (Hilary of Poitiers, On Synods 17.51 (PL 10:518–19); 23.57 (PL 10:520).) For the nature of one innascible God demands that one God be preached.

Hence, certain philosophers asserted that in immaterial things there cannot be plurality except in respect of origin. For one nature can be equally in several subjects on account of the division of matter, which does not apply to God.

Wherefore, it is impossible to assert in God but one innascible person that does not proceed from another. Now, if other persons proceed from him, this must be through some action; not, however, by an action passing into a subject outside the agent, as heating and cutting are the actions of fire and saw, and as creation is the act of God himself, since then the proceeding persons would be outside the divine nature.

It follows, then, that the procession of persons into the one divine nature is only according to activities that do not pass outside but remain in the one acting. Now, in an intellectual nature these are but two: to understand and to will. However, according to each of these actions, something is found proceeding when the activities are perfected. For understanding is not perfected without something being conceived in the mind of the one who understands, and this is called a “word”; for before some conception is fixed in our mind we are not said to understand but to think in order to understand. In like manner, willing is itself perfected by a love proceeding from the lover through his will, for love is nothing other than the fixation of the will in the good willed.

Now, in creatures, word and love are not persons subsisting in the understanding and willing nature. For to understand and to will for a creature is not its to be. Hence, its word and love are certain things supervening on the understanding and willing creature, as certain accidents of them. But seeing that in God, to be, to understand, and to will are the same thing, it follows of necessity that the word and the love in God are not accidents but subsist in the divine nature. However, in God, there is but one simple understanding and one simple willing, since by understanding his own essence he understands all things, and by willing his own goodness he wills all the things that he wills. Hence, there is but one Word and one Love in God.

Now, the order of understanding and willing does not stand in the same way in God as it does in us. For we receive our intellectual knowledge from external realities, and by our will we tend into something external as an end. Wherefore, our understanding is according to a movement from realities to the soul, but our willing is according to a movement from the soul to the realities. On the other hand, God does not receive knowledge from realities, but by his knowledge he is the cause of the realities, nor by his will does he tend into anything external as his end, but he orders all external things into himself as their end. Accordingly, both in us and in God there is a certain circling within the acts of the intellect and will, for the will returns to that whence came the beginning of understanding. But in us the circle is completed at that which is external, as long as the external good moves our intellect, and the intellect moves the will, and the will by appetite and love tends into the external good; in God, on the other hand, the circle is completed in him. For God, by understanding himself, conceives his own Word, which is also the type of all things understood by him, on account of the fact that he understands all things by understanding his very self; and from this Word he proceeds into the love of all things and of his very self. Thus, someone has said that a monad engendered a monad and reflected its own ardor upon itself. (The citation is from the Hermetica, a set of texts attributed to Mercury or Hermes Trismegistus (that is, “thrice-great”), the Greek name of the Egyptian divinity Thoth; the texts originated from Hellenistic Egypt.) And after the circle has been closed, nothing further can be added; therefore no third procession within the divine nature can follow, although there follows a further procession into an external nature.

Hence, in God there must be but one person that does not proceed, and only two persons that proceed, one of whom proceeds as Love, the other as Word; and thus, the persons in God are three in number.

In creatures, a likeness to this Trinity appears in three ways.

First, as an effect reflects its cause; and in this way the principle of the whole divinity, namely, the Father, is represented by that which is first in the creature, namely, by being in itself one subsistent thing. The Word is represented by the form of each creature, for in those things which are done by an intellectual agent the form of the effect derives from the concept of his intelligence. And the Love is represented in the order of creatures, for from the fact that God loves his very self, he directs all things to himself in a certain order. Wherefore this likeness is said to be that of a footprint, which represents a foot as an effect its cause.

Second, according to the same account of activity; and thus, it is represented in the rational creature alone, who like God can understand and love himself, and in this way produces his own Word and Love. And this is called the likeness of the natural image, for those things bear the image of other things when they present a like species.

Third, through the unity of object, inasmuch as the rational creature understands and loves God; this is a kind of conformity of union that is found in the saints alone, who understand and love the same thing that God understands and loves.

Of the first kind of likeness, it is written, perhaps you will understand the footprints of God? (Job 11:7). Of the second: let us make man to our own image and likeness (Gen 1:26), and this is called the image of creation. Of the third, it is written: but we, beholding the glory of the Lord with open face, are transformed into the same image (2 Cor 3:18), and this is called the image of re-creation.

Reply Obj. 1: The reason why Augustine says that one should not say that the Son was unable to beget, but that there was no need to beget, is that it was not through a lack of ability that the Son does not beget; such that the words was unable are being taken privatively and not simply negatively, and the words there was no need to indicate that the consequence would be unfitting if, in God, the Son were to beget another Son.

How this is unfitting may be considered in four ways.

First, seeing that in God the Son proceeds as Word, if the Son begot a Son it would follow that, in God, a Word proceeds from a Word. And this is impossible except in an inquiring and discursive intellect, wherein a word proceeds from a word, when from the consideration of one truth it proceeds to the consideration of another truth. This is in no way fitting for the perfection and simplicity of the divine intellect, which at one glance sees all things at the same time.

Second, because that which renders a thing individual and incommunicable cannot possibly be common to several. For that through which Socrates is this something cannot even be conceived as being in several things. Hence, if in God filiation were common to several persons, it would not constitute the incommunicable person of the Son; and thus, the Son would have to be constituted as an individual person by something absolute, and this is incompatible with the unity of the divine essence.

Third, because nothing existing as one in species can be multiplied in number except by reason of matter; and for this reason there can be but one essence in God, because the divine essence is utterly immaterial. Now, if there were several Sons in God, there would also be several filiations, and consequently they would have to be multiplied according to matter subjected to them; and this is incompatible with the divine immateriality.

Fourth, because someone is a son because he proceeds naturally. Now, nature stands determinately to one effect, except when several effects naturally arise from something accidentally, on account of the matter being divided; and consequently, where the nature is utterly immaterial, there can be but one Son.

Reply Obj. 2: Something can be of a certain nature in two ways.

First, as considered absolutely; and thus, whatsoever pertains to some nature must belong to every supposit of that nature. In this sense, it is fitting to the divine nature to be omnipotent, creator, and other similar attributes that are common to the three persons.

Second, something pertains to a nature as considered in a certain single supposit; and thus, whatsoever belongs to the nature does not necessarily belong to every supposit of that nature. For just as the nature of the genus includes something in one species which does not belong to another species (for instance, certain things follow on the sensitive nature in man but not in the brute animals, such as an excelling sense of touch, recollection, and so forth), so something pertains to the nature of the species insofar as it is in one individual that does not belong to another individual of the same species. For instance, it is clear that it belongs to human nature as it was in Adam that it was not received through a natural generation, which does not apply to other individuals of human nature. In this way, then, the ability to beget follows the divine nature as it is in the person of the Father; this is clear because the Father is not constituted an incommunicable person otherwise than by the very paternity that belongs to him as begetting; hence, although the Son is a perfect supposit of the divine nature, it does not follow that he can beget.

Reply Obj. 3: Although the Father can beget whereas the Son cannot, it does not follow that the Father has a power which the Son has not. For in the Father and the Son it is the same power whereby the Father begets and the Son is begotten. For power is something absolute; wherefore, it is not distinguished in God, just as neither is goodness nor anything else of the kind. On the other hand, in God, to beget and to be begotten do not signify something absolute, but merely a relation. Now, the opposite relations in the one same absolute are in communion in the divine and do not divide it, just as it is clear that the one essence is in Father and Son; wherefore, neither is power divided in God through the fact that it is for begetting and being begotten. In fact, not even in creatures does every distinction of objects differentiate powers, but only when the objects differ formally within the same genus. For example, the power of sight is not differentiated by seeing a man and seeing a donkey, for this difference is not one of the sensible as sensible. And in like manner the absolute is not distinguished by relation in God.

Reply Obj. 4: In every activity that passes from the agent into an extraneous reality, there must be a principle in the agent whereby it is an agent and another principle in the patient whereby it is a patient. But in an activity that does not pass into an extraneous reality but remains in the agent, only one principle is required; for example, in order to will, a principle is necessary on the part of the one willing whereby he can will. Now, in creatures, generation is an operation passing into an extraneous reality; wherefore, the active power in the generator must be distinct from the passive power in the generated. But the divine generation is viewed according to an activity that does not pass into anything extraneous but remains within, that is, according to the conception of the Word. Wherefore, there is no need for there to be an active power in the Father that is other than a passive power in the Son.

Reply Obj. 5: Heat and dryness considered in themselves are certain qualities, yet we may call them powers inasmuch as they are principles of certain actions. Hence, it is clear that although the primary and remote root, which is the subject, is but one, still the proximate root, which is the quality, is not one.

Reply Obj. 6: As the Father is God begetting whereas the Son is God begotten, so must we say that the Father is wise as conceiving while the Son is wise as the conceived Word. For the Son, in that he is the Word, is a conception of the wise. But since whatsoever is in God is God, it follows that the very conception of a wise God is God, is wise, is powerful, and whatsoever else is appropriate to God.

Reply Obj. 7: Taken in its proper sense, “word” cannot be attributed to God otherwise than personally. For in God there cannot be any origination but what is immaterial, and what is fitting to an intellectual nature, such as the origination of Word and Love. Wherefore, if the procession of Word and Love is not enough to indicate a personal distinction, no personal distinction will be possible in God. Thus, both in the beginning of his gospel, and in his first epistle, John too employs the term Word instead of Son, nor may we in speaking of God express ourselves in terms other than those of Holy Scripture.

Reply Obj. 8: “To speak” may be taken in two senses.

First, properly, insofar as speaking is the same thing as conceiving a word: and in this sense, Augustine says that in God each person does not speak, but the Father alone. (Augustine, On the Trinity 7.1 (PL 42:933–34).)

Second, in a common sense, insofar as speaking is nothing other than understanding; and thus, Anselm says that not only the Father speaks but also the Son and the Holy Spirit, and though there are three who speak, there is but one Word, which is the Son; because the Son alone is the concept of the understanding Father and the one conceiving the Word. (Anselm of Canterbury, Monologion 62–63 (PL 158:207–10).)

Reply Obj. 9: That there is generation in God does not follow from the mere fact that God gives generation to others as an efficient cause, since for the sake of reason it would follow that there is motion in God because he gives motion to others. However, it does follow that there is generation in God from the fact that he gives generation to others as both an efficient and an exemplary cause; moreover, the Father is the exemplar of generation as begetting, whereas the Son is the exemplar as begotten. Wherefore, it does not follow that he would beget.

Reply Obj. 10: Generation is an activity of the divine nature insofar as it is in the person of the Father, as we have already stated, hence it does not follow that it belongs to the Son.

Reply Obj. 11: Since filiation is a relation arising from a determinate mode of origin, namely, according to nature, it is impossible that a filiation differ from a filiation by a formal difference—unless perhaps according to a difference of the natures that are communicated by generation; thus, we might say that the species of filiation whereby this man is a son differs from the species of filiation whereby this horse is a son. But in God there is but one nature, whence there cannot be several formally different filiations; and it is evident that it also cannot be so materially. Consequently, in God there is but one filiation and one Son.

Reply Obj. 12: One brilliance proceeds from another brilliance by the diffusion of light onto another subject; wherefore, this is clearly due to a division of matter, which is impossible in God.

Reply Obj. 13: A thing is loved insofar as it is good: hence, since one and the same goodness is that of the Father, Son, and Holy Spirit, with the same Love, which is the Holy Spirit, the Father loves the Son, the Holy Spirit, and all creatures. Even so by the same Word, which is the Son, he speaks himself, the Son, the Holy Spirit, and all creatures.

Reply Obj. 14: Goodness is that at which the activity of the living is completed, and which abides in the one acting. For first something is understood as true, and then it is desired as good, and there the internal activity stops and rests as in its end. But from this point begins the process of an external activity, because through the intellect’s desire and love for something that it has already considered as good, it begins to act externally towards that good. Wherefore, from the very fact that goodness is appropriated to the Holy Spirit, it is fitting for us to conclude that the procession of the divine persons goes no further. What does follow, however, is the procession of creatures, which is outside the divine nature.

Reply Obj. 15: Of all lines the circle is the most perfect because it admits of no addition. Hence, this very thing pertains to the perfection of the Holy Spirit, that he, as it were, completes the circle of the divine origin, such that no further addition is possible, as we have already shown above.

Reply Obj. 16: In the reception or communication of the divine nature, there is no other difference but that arising from the relations; and this difference cannot constitute an inequality of perfection because, as Augustine says in Against Maximinus, when we ask who proceeds from whom, it is a question of origin, not of equality or inequality. (Augustine, Against Maximinus 2.18, para. 3 (PL 42:786).)

Reply Obj. 17: Just as the communication of the divine nature by the Father to the Son belongs to their perfection, so the perfect reception of the communicated nature belongs to the perfection of the Holy Spirit; and both perfections differ not in quantity but only in respect of relation, which does not constitute an imperfection, as was said.

Reply Obj. 18: As we have already observed, that which makes a person incommunicable cannot be common to many. Hence, the result of sharing therein would be not enjoyment but the destruction of the distinction of the persons. Thus, were the Father to have a companion in the divine nature to share his paternity, there would be a confusion of persons; and the same applies to filiation and procession.

Reply Obj. 19: The other attributes have no intrinsic activity according to which a procession of a divine person could be considered, the way intellect and will do.

Reply Obj. 20: The process of nature and the process of the intellect have this in common, that in either case one thing proceeds from one thing as a likeness of that whence it proceeds. But love that proceeds according to the will proceeds from two who love each other mutually. Nor can we infer that, because it is love, it is a likeness of the lover. Wherefore, in God the same person proceeds through the mode of nature and intellect, namely, as Son and as Word, whereas it is another person that proceeds through the mode of will as Love.

Reply Obj. 21: Although there are five notions in God, there are but three personal properties constituting the persons; and therefore, there are but three persons.

Reply Obj. 22: God’s ideal relations are oriented toward what is outside, namely, to created things; and consequently, they do not cause a distinction of persons in him.

We must also reply to the other arguments, which would prove that there are fewer than three persons in God.

Reply Obj. 1: In every created nature, there are found many modes of procession, yet the specific nature is not communicated in each of them; and the reason of this is to be found in the imperfection of created nature, inasmuch as not everything of a created nature subsists in itself. Thus, the word that proceeds from a man’s intellect is not something subsistent, nor is the love that proceeds from the human will. But the son who is begotten through an activity of nature does subsist in human nature; wherefore this is the only way in which human nature is communicated, although there are several modes of procession. On the other hand, whatsoever is in God is subsistent; wherefore, in God the divine nature is communicated in every mode of procession.

Reply Obj. 2: Nothing prevents something from naturally proceeding even from the will; for the will also naturally wills and loves something, that is, happiness and the knowledge of the truth. Hence, there is no reason why the Holy Spirit should not proceed naturally from the Father and the Son, although he proceeds through the mode of will.

Reply Obj. 3: Although will and intellect do not differ in God except according to account, he that proceeds through the mode of intellect must be really distinct from him who proceeds through the mode of will. For the Word, which proceeds through the mode of intellect, proceeds from only one, as from a speaker, while the Holy Spirit, who proceeds through the mode of will as Love, must proceed from two who love each other mutually, or from one who speaks and his Word. For nothing can be loved unless the intellect has first conceived it by its word. Hence, he who proceeds through the mode of will must be from him who proceeds through the mode of intellect, and consequently must be distinguished from him.

Reply Obj. 4: He who is from another in God can be so in two ways: namely, either through the mode of a Word or through the mode of a Love. Hence, he who is from another, spoken of in a general way, is not enough to constitute an incommunicable person, but only insofar as he is made determinate to things that are proper.

Reply Obj. 5: In God, there are four relations, not only two, but only three of them are personal, for one (namely, common spiration) is not a personal property, seeing that it is common to two persons; for this reason there are only three persons in God.

Reply Sed Contra: We grant the remaining arguments.