Summa Theologica, Part I (Prima Pars) From the Complete...

Reply Obj. 2: Where we have equality in respect of virtual quantity, equality includes likeness and something besides, because it excludes excess. For whatever things have a common form may be said to be alike, even if they do not participate in that form equally, just as the air may be said to be like fire in heat; but they cannot be said to be equal if one participates in the form more perfectly than another. And because not only is the same nature in both Father and Son, but also is it in both in perfect equality, therefore we say not only that the Son is like to the Father, in order to exclude the error of Eunomius, but also that He is equal to the Father to exclude the error of Arius.

Reply Obj. 3: Equality and likeness in God may be designated in two ways—namely, by nouns and by verbs. When designated by nouns, equality in the divine persons is mutual, and so is likeness; for the Son is equal and like to the Father, and conversely. This is because the divine essence is not more the Father's than the Son's. Wherefore, just as the Son has the greatness of the Father, and is therefore equal to the Father, so the Father has the greatness of the Son, and is therefore equal to the Son. But in reference to creatures, Dionysius says (Div. Nom. ix): "Equality and likeness are not mutual." For effects are said to be like their causes, inasmuch as they have the form of their causes; but not conversely, for the form is principally in the cause, and secondarily in the effect.

But verbs signify equality with movement. And although movement is not in God, there is something that receives. Since, therefore, the Son receives from the Father, this, namely, that He is equal to the Father, and not conversely, for this reason we say that the Son is equalled to the Father, but not conversely.

Reply Obj. 4: In the divine persons there is nothing for us to consider but the essence which they have in common and the relations in which they are distinct. Now equality implies both—namely, distinction of persons, for nothing can be said to be equal to itself; and unity of essence, since for this reason are the persons equal to one another, that they are of the same greatness and essence. Now it is clear that the relation of a thing to itself is not a real relation. Nor, again, is one relation referred to another by a further relation: for when we say that paternity is opposed to filiation, opposition is not a relation mediating between paternity and filiation. For in both these cases relation would be multiplied indefinitely. Therefore equality and likeness in the divine persons is not a real relation distinct from the personal relations: but in its concept it includes both the relations which distinguish the persons, and the unity of essence. For this reason the Master says (Sent. i, D, xxxi) that in these "it is only the terms that are relative." _______________________

Objection 1: It would seem that the person proceeding is not co-eternal with His principle, as the Son with the Father. For Arius gives twelve modes of generation. The first mode is like the issue of a line from a point; wherein is wanting equality of simplicity. The second is like the emission of rays from the sun; wherein is absent equality of nature. The third is like the mark or impression made by a seal; wherein is wanting consubstantiality and executive power. The fourth is the infusion of a good will from God; wherein also consubstantiality is wanting. The fifth is the emanation of an accident from its subject; but the accident has no subsistence. The sixth is the abstraction of a species from matter, as sense receives the species from the sensible object; wherein is wanting equality of spiritual simplicity. The seventh is the exciting of the will by knowledge, which excitation is merely temporal. The eighth is transformation, as an image is made of brass; which transformation is material. The ninth is motion from a mover; and here again we have effect and cause. The tenth is the taking of species from genera; but this mode has no place in God, for the Father is not predicated of the Son as the genus of a species. The eleventh is the realization of an idea [ideatio], as an external coffer arises from the one in the mind. The twelfth is birth, as a man is begotten of his father; which implies priority and posteriority of time. Thus it is clear that equality of nature or of time is absent in every mode whereby one thing is from another.

Obj. 3: Further, everything which is corrupted ceases to be. Hence everything generated begins to be; for the end of generation is existence. But the Son is generated by the Father. Therefore He begins to exist, and is not co-eternal with the Father.

Obj. 4: Further, if the Son be begotten by the Father, either He is always being begotten, or there is some moment in which He is begotten. If He is always being begotten, since, during the process of generation, a thing must be imperfect, as appears in successive things, which are always in process of becoming, as time and motion, it follows that the Son must be always imperfect, which cannot be admitted. Thus there is a moment to be assigned for the begetting of the Son, and before that moment the Son did not exist.

I answer that, We must say that the Son is co-eternal with the Father. In proof of which we must consider that for a thing which proceeds from a principle to be posterior to its principle may be due to two reasons: one on the part of the agent, and the other on the part of the action. On the part of the agent this happens differently as regards free agents and natural agents. In free agents, on account of the choice of time; for as a free agent can choose the form it gives to the effect, as stated above (Q. 41, A. 2), so it can choose the time in which to produce its effect. In natural agents, however, the same happens from the agent not having its perfection of natural power from the very first, but obtaining it after a certain time; as, for instance, a man is not able to generate from the very first. Considered on the part of action, anything derived from a principle cannot exist simultaneously with its principle when the action is successive. So, given that an agent, as soon as it exists, begins to act thus, the effect would not exist in the same instant, but in the instant of the action's termination. Now it is manifest, according to what has been said (Q. 41, A. 2), that the Father does not beget the Son by will, but by nature; and also that the Father's nature was perfect from eternity; and again that the action whereby the Father produces the Son is not successive, because thus the Son would be successively generated, and this generation would be material, and accompanied with movement; which is quite impossible.

Reply Obj. 1: As Augustine says (De Verbis Domini, Serm. 38), no mode of the procession of any creature perfectly represents the divine generation. Hence we need to gather a likeness of it from many of these modes, so that what is wanting in one may be somewhat supplied from another; and thus it is declared in the council of Ephesus: "Let Splendor tell thee that the co-eternal Son existed always with the Father; let the Word announce the impassibility of His birth; let the name Son insinuate His consubstantiality." Yet, above them all the procession of the word from the intellect represents it more exactly; the intellectual word not being posterior to its source except in an intellect passing from potentiality to act; and this cannot be said of God.

Reply Obj. 3: Every corruption is a change; and so all that corrupts begins not to exist and ceases to be. The divine generation, however, is not changed, as stated above (Q. 27, A. 2). Hence the Son is ever being begotten, and the Father is always begetting.

Reply Obj. 4: In time there is something indivisible—namely, the instant; and there is something else which endures—namely, time. But in eternity the indivisible "now" stands ever still, as we have said above (Q. 10, A. 2, ad 1; A. 4, ad 2). But the generation of the Son is not in the "now" of time, or in time, but in eternity. And so to express the presentiality and permanence of eternity, we can say that "He is ever being born," as Origen said (Hom. in Joan. i). But as Gregory [*Moral. xxix, 21] and Augustine [*Super Ps. 2:7] said, it is better to say "ever born," so that "ever" may denote the permanence of eternity, and "born" the perfection of the only Begotten. Thus, therefore, neither is the Son imperfect, nor "was there a time when He was not," as Arius said. _______________________

Objection 1: It would seem that among the divine persons there does not exist an order of nature. For whatever exists in God is the essence, or a person, or a notion. But the order of nature does not signify the essence, nor any of the persons, or notions. Therefore there is no order of nature in God.

Obj. 2: Further, wherever order of nature exists, there one comes before another, at least, according to nature and intellect. But in the divine persons there exists neither priority nor posteriority, as declared by Athanasius. Therefore, in the divine persons there is no order of nature.

I answer that, Order always has reference to some principle. Wherefore since there are many kinds of principle—namely, according to site, as a point; according to intellect, as the principle of demonstration; and according to each individual cause—so are there many kinds of order. Now principle, according to origin, without priority, exists in God as we have stated (Q. 33, A. 1): so there must likewise be order according to origin, without priority; and this is called 'the order of nature': in the words of Augustine (Contra Maxim. iv): "Not whereby one is prior to another, but whereby one is from another."

Reply Obj. 2: In things created, even when what is derived from a principle is co-equal in duration with its principle, the principle still comes first in the order of nature and reason, if formally considered as principle. If, however, we consider the relations of cause and effect, or of the principle and the thing proceeding therefrom, it is clear that the things so related are simultaneous in the order of nature and reason, inasmuch as the one enters the definition of the other. But in God the relations themselves are the persons subsisting in one nature. So, neither on the part of the nature, nor on the part the relations, can one person be prior to another, not even in the order of nature and reason.

Objection 1: It would seem that the Son is not equal to the Father in greatness. For He Himself said (John 14:28): "The Father is greater than I"; and the Apostle says (1 Cor. 15:28): "The Son Himself shall be subject to Him that put all things under Him."

Obj. 3: Further, wherever there exist a whole and a part, many parts are more than one only, or than fewer parts; as three men are more than two, or than one. But in God a universal whole exists, and a part; for under relation or notion, several notions are included. Therefore, since in the Father there are three notions, while in the Son there are only two, the Son is evidently not equal to the Father.

I answer that, The Son is necessarily equal to the Father in greatness. For the greatness of God is nothing but the perfection of His nature. Now it belongs to the very nature of paternity and filiation that the Son by generation should attain to the possession of the perfection of the nature which is in the Father, in the same way as it is in the Father Himself. But since in men generation is a certain kind of transmutation of one proceeding from potentiality to act, it follows that a man is not equal at first to the father who begets him, but attains to equality by due growth, unless owing to a defect in the principle of generation it should happen otherwise. From what precedes (Q. 27, A. 2; Q. 33, AA. 2 ,3), it is evident that in God there exist real true paternity and filiation. Nor can we say that the power of generation in the Father was defective, nor that the Son of God arrived at perfection in a successive manner and by change. Therefore we must say that the Son was eternally equal to the Father in greatness. Hence, Hilary says (De Synod. Can. 27): "Remove bodily weakness, remove the beginning of conception, remove pain and all human shortcomings, then every son, by reason of his natural nativity, is the father's equal, because he has a like nature."

Reply Obj. 1: These words are to be understood of Christ's human nature, wherein He is less than the Father, and subject to Him; but in His divine nature He is equal to the Father. This is expressed by Athanasius, "Equal to the Father in His Godhead; less than the Father in humanity": and by Hilary (De Trin. ix): "By the fact of giving, the Father is greater; but He is not less to Whom the same being is given"; and (De Synod.): "The Son subjects Himself by His inborn piety"—that is, by His recognition of paternal authority; whereas "creatures are subject by their created weakness."

Reply Obj. 2: Equality is measured by greatness. In God greatness signifies the perfection of nature, as above explained (A. 1, ad 1), and belongs to the essence. Thus equality and likeness in God have reference to the essence; nor can there be inequality or dissimilitude arising from the distinction of the relations. Wherefore Augustine says (Contra Maxim. iii, 13), "The question of origin is, Who is from whom? but the question of equality is, Of what kind, or how great, is he?" Therefore, paternity is the Father's dignity, as also the Father's essence: since dignity is something absolute, and pertains to the essence. As, therefore, the same essence, which in the Father is paternity, in the Son is filiation, so the same dignity which, in the Father is paternity, in the Son is filiation. It is thus true to say that the Son possesses whatever dignity the Father has; but we cannot argue—"the Father has paternity, therefore the Son has paternity," for there is a transition from substance to relation. For the Father and the Son have the same essence and dignity, which exist in the Father by the relation of giver, and in the Son by relation of receiver.

Reply Obj. 3: In God relation is not a universal whole, although it is predicated of each of the relations; because all the relations are one in essence and being, which is irreconcilable with the idea of universal, the parts of which are distinguished in being. Person likewise is not a universal term in God as we have seen above (Q. 30, A. 4). Wherefore all the relations together are not greater than only one; nor are all the persons something greater than only one; because the whole perfection of the divine nature exists in each person. _______________________