FIRST ARTICLE: WHETHER THE UNION OF THE INCARNATE WORD TOOK PLACE IN THE NATURE

State of the question. The meaning is: Does this union, referred to in the heading of this article, result in only one nature, as Eutyches and Dioscorus taught? In this article we have the refutation of Monophysitism.

The reason why St. Thomas refutes Eutyches before Nestorius is that he is following the logical order and not the historical order. It is in accordance with logical procedure to state first in what this union does not consist, and afterward what constitutes it.

The difficulties presented at the beginning of this article are arguments of Eutyches, who sought to defend the teaching of St. Cyril of Alexandria against the Nestorians, but Eutyches had a wrong conception of St. Cyril's teaching.

First difficulty. The text quoted by St. Thomas in this first objection is not St. Cyril's, as found in the acts of the Council of Chalcedon, but is to be attributed to the heretic Dioscorus. However, since the words can be interpreted in a good sense and are attributed to St. Cyril, they are examined by St. Thomas here. The text reads: "We must understand not two natures, but one incarnate nature of the Word of God." It does not say simply "one nature," but "one incarnate nature"; and this is true, since only the divine nature became incarnate, as explained afterward in the Second Council of Constantinople,[400] and the words of the council on this point are quoted by St. Thomas in his reply to the first objection.

St. Cyril had said that this union was not moral but physical.[401] By calling the union physical, St. Cyril by no means meant that it signified a commingling of the two natures, but that the union was more than moral and accidental, and as used by St. Cyril the expression came to be commonly accepted as equivalent to hypostatic union.[402]

In the Latin Church, the terms "person" and "nature" have a distinct meaning already from the time of Tertullian, who admits in Christ one person but two natures, almost as clearly as St. Hilary and St. Augustine declared after him.[403]

Second difficulty. It is taken from the Athanasian Creed, in which it is said of Christ: "As the rational soul and the flesh together are one man, so God and man together are one Christ." But the soul and the body unite in constituting one nature. Eutyches applied this remote analogy in the literal sense.

Third difficulty. St. Gregory Nazianzen says: "The human nature[in Christ] is deified," just as St. Cyril had said, "the divine nature is incarnate." But some could understand the expression to mean a certain transmutation and blending of the natures.

Eutyches understood the expression in the following sense: "That our Lord was of two natures before the union; but after the union there was one nature." Eutyches said: "Christ is of two natures, not in two natures, nor is He consubstantial with us according to the flesh; the deity suffered and was buried."

The reply of St. Thomas, notwithstanding these difficulties, is as follows: The union of the Word incarnate did not take place in the nature or essence, such that in Christ there is only one nature. In fact, this is absolutely impossible; but there are in Christ two distinct natures.

This conclusion is a dogma of our faith defined as such against Eutyches in the Council of Chalcedon in these words: "We teach that Christ... is perfect as God and that He is perfect as man, true God and true man... and that He is in two natures,[404] without confusion, ... the properties of each nature being preserved, and that He is in one person and one subsistence."[405] The Second Council of Constantinople defines similarly.[406] Likewise the Athanasian Creed declares: "One altogether, not by confusion of substance, but by unity of person."[407] Subsequent councils and professions of faith give similar definitions.

Scriptural proof. From the many passages already quoted, it is evident that Christ is truly God and truly man. It suffices here to give the following text from the Old Testament: "A child is born to us... and His name shall be called... God the Mighty."[408] Thus also in the New Testament, the greater and especially more sublime prophets were already illumined to perceive the divine nature of the promised Messias.

From the New Testament we have the following texts: "I am the way and the truth and the life."[409] "Who being in the form of God, thought it not robbery to be equal with God, but emptied Himself, taking the form of a servant."[410] Here we have the twofold form or nature, namely, of God and the servant, each distinct, without confusion (of natures). Again we read: "That which was from the beginning, which we have heard, which we have seen with our eyes, which we have looked upon, and our hands have handled, of the Word of life."[411] Here again we have the two natures distinctly mentioned, namely, the one divine in the words "of the Word of life," the other the human nature, in the words "which we have looked upon and our hands have handled."

Proof from reason. It is given in the body of the article, in which, from an analysis of the notion of nature, the absurdity of Monophysitism is shown, which is just as absurd as pantheism. There are two parts to this article. The first part considers what is meant by the word "nature." The second part shows the impossibility of the union taking place in the nature.

First part. It determines, by the way of invention, following Aristotle[412] and Boethius, the various acceptations of the term "nature."

This noun signifies: 1. birth or begetting of living beings; 2. the principle of this begetting; 3. whatever intrinsic principle of motion essentially belongs to the subject in which it is, such as the principle of the vegetative life, or of the sensitive life, in each and every subject; 4. The substantial form, which is this radical principle of natural operations, for instance, in the plant; 5. matter, which is the principle of natural passivity; thus it is said that the animal is naturally mortal; 6. the essence also of spiritual things and of God Himself, inasmuch as this essence is the radical principle of their operations. So says Boethius, who is quoted in this article, and St. Thomas concludes: "But we are now speaking of nature as it signifies the essence."

Second part. It is shown to be impossible for the union to take place in the nature. The argument of St. Thomas may be reduced to the following syllogism. There are only three possible ways for the union to take place in the nature, namely: 1. by the composition of things that are perfect in themselves and that remain perfect; 2. by the mixture of things perfect in themselves that have undergone a change; 3. by the union of things imperfect in themselves that have been neither mixed nor changed.

But these ways are incompatible. Therefore it is impossible for the union to take place in the nature.

Of two perfect things

Of imperfect things

The whole article must be read.

More briefly: This union does not take place in the nature, so that there results from it but one nature:

Objection. Some have said that there can be a transubstantiation of the human nature into the divine, just as there is a transubstantiation of the bread into the body of Christ, without any corruption in the process.

Reply. Even if this transubstantiation were not incompatible, the result of this would be that after the Incarnation the human nature would cease to exist. and thus Christ would not be truly man, which is against the faith. Christ is truly man, for He was born, suffered, and died.

The reply of St. Thomas is confirmed from the solution of the difficulties presented at the beginning of the article.

Reply to first objection. This difficulty is taken from the text attributed to St. Cyril and explained by the Second Council of Constantinople,[414] in the sense that the physical union,[415] which St. Cyril spoke of when arguing against the Nestorians, who admitted only a moral union, was meant by St. Cyril as referring not to a union in the nature, but in the person, or to a subsistential union, as the words themselves denote.[416]

Reply to second objection. When the Athanasian Creed says, "As the rational soul and flesh together are one man, so God and man together are one Christ," the analogy has its foundation in the similarity between the parts, namely, inasmuch as soul and body constitute one person, but not in the dissimilarity, namely, inasmuch as the soul and the body constitute one nature.

Reply to third objection. Damascene explains correctly the words attributed to St. Cyril, who says: "The divine nature is incarnate," inasmuch as it is united personally to flesh. He gives a similar interpretation to the words of St. Gregory Nazianzen, who says that "the human nature is deified"; namely, not by change, but by being united with the Word, the properties of each nature remaining intact.