Of Equality and Likeness Among the Divine Persons

Of Equality and Likeness Among the Divine Persons — St. Thomas Aquinas asks: Whether there is equality in God?; Whether the person proceeding is co-eternal with His principle, as the Son with the Father?; Whether in the divine persons there exists an order of nature?; Whether the Son is equal to the Father in greatness?; Whether the Son is in the Father, and conversely?; Whether the Son is equal to the Father in power?.

We now have to consider the persons as compared to one another: firstly, with regard to equality and likeness; secondly, with regard to mission. Concerning the first there are six points of inquiry.

Article 1: Whether there is equality in God?

Athanasius says that "the three persons are co-eternal and co-equal to one another."

We must needs admit equality among the divine persons. For, according to the Philosopher (Metaph. x, text 15,16, 17), equality signifies the negation of greater or less. Now we cannot admit anything greater or less in the divine persons; for as Boethius says (De Trin. i): "They must needs admit a difference [namely, of Godhead] who speak of either increase or decrease, as the Arians do, who sunder the Trinity by distinguishing degrees as of numbers, thus involving a plurality." Now the reason of this is that unequal things cannot have the same quantity. But quantity, in God, is nothing else than His essence. Wherefore it follows, that if there were any inequality in the divine persons, they would not have the same essence; and thus the three persons would not be one God; which is impossible. We must therefore admit equality among the divine persons.

Article 2: Whether the person proceeding is co-eternal with His principle, as the Son with the Father?

Athanasius declares that "all the three persons are co-eternal with each other."

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 (), 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 (), 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. Therefore we conclude that the Son existed whensoever the Father existed and thus the Son is co-eternal with the Father, and likewise the Holy Ghost is co-eternal with both.

Article 3: Whether in the divine persons there exists an order of nature?

Where plurality exists without order, confusion exists. But in the divine persons there is no confusion, as Athanasius says. Therefore in God order exists.

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 (): 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."

Article 4: Whether the Son is equal to the Father in greatness?

It is said (Phil. 2:6): "He thought it not robbery to be equal with God."

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 (; ), 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."

Article 5: Whether the Son is in the Father, and conversely?

It is said (Jn. 14:10): "I am in the Father, and the Father is in Me."

There are three points of consideration as regards the Father and the Son; the essence, the relation and the origin; and according to each the Son and the Father are in each other. The Father is in the Son by His essence, forasmuch as the Father is His own essence and communicates His essence to the Son not by any change on His part. Hence it follows that as the Father's essence is in the Son, the Father Himself is in the Son; likewise, since the Son is His own essence, it follows that He Himself is in the Father in Whom is His essence. This is expressed by Hilary (De Trin. v), "The unchangeable God, so to speak, follows His own nature in begetting an unchangeable subsisting God. So we understand the nature of God to subsist in Him, for He is God in God." It is also manifest that as regards the relations, each of two relative opposites is in the concept of the other. Regarding origin also, it is clear that the procession of the intelligible word is not outside the intellect, inasmuch as it remains in the utterer of the word. What also is uttered by the word is therein contained. And the same applies to the Holy Ghost.

Article 6: Whether the Son is equal to the Father in power?

It is said (Jn. 5:19): "Whatsoever things the Father doth, these the Son also doth in like manner."

The Son is necessarily equal to the Father in power. Power of action is a consequence of perfection in nature. In creatures, for instance, we see that the more perfect the nature, the greater power is there for action. Now it was shown above () that the very notion of the divine paternity and filiation requires that the Son should be the Father's equal in greatness---that is, in perfection of nature. Hence it follows that the Son is equal to the Father in power; and the same applies to the Holy Ghost in relation to both.