This is my second batch of summaries for Christology. Fire away! I can use all the help I can get in sharpening my understanding of St. Thomas.
In article 1, St. Thomas dispenses with the Monophysite argument that the union of the word took place in the nature. The first objection, he notes, is based on a selective reading of St. Cyril. The second objection, he notes, is essentially a false analogy. The third objection, he notes, confuses two natures being changed as opposed to two natures being joined and that the Divine nature cannot actually be the form of a body but is simply joined to the flesh. He goes on to explain that nature has two senses: one, which deals with the begetting of things (birth) and a second, which deals with that which is essential to a thing (its quiddity). Union couldn’t then, be accidental, as with a composition of different elements; nor could it be a mixture of elements, which would result in nature neither Divine nor human. Nor could two natures be combined as two imperfect things, like members of a body, since each is perfectly complete or “has its specific perfection.”
This second article appears to be geared toward the opposite position at the Council of Chalcedon—that taken by Nestorius—that the union did not take place in the Person of the Word of God. In response to the first objection, St. Thomas notes that in God, nature and Person are not distinct (owing to God’s simplicity), but that the words “nature” and “person” do not mean the same thing. However, human nature is united to the Person of the Word without changing the Divine nature. In response to the second, he notes that human nature has greater dignity because it exists in the Person of the Word. In response to the third objection, he points out that the human nature assumed by Christ does not have its own personality because it did not exist apart from the Person of Christ. He then notes that while in the Divine Person, nature and essence are the same, that in created things, nature and person are not the same because other things adhere to the person that are not essential. Yet the suppositum is taken as whole, regardless of whether what is joined to it is essential or accidental. Hence, the human nature of the Word, which doesn’t belong to the Divine nature, is united in the Person of the Word.
In article 3, the Angelic Doctor addresses whether the union of natures in Christ took place in the suppositum or hypostasis. In response to objection 1 that Augustine and Pope Leo both refer to an “other” or to the Word and man as distinct, St. Thomas notes that they referred to His natures, and not to distinct hypostasis. To objection 2, he responds that a hypostasis includes those things in union to a substance and not only the substance itself. In objection 3, he explains that a thing is placed in a genus or species not based on individuating elements but by nature or essence. He sums up by noting that a person is simply a suppositum or hypostasis with a rational nature. To attribute a thing to a person is the same as to attribute it to their hypostasis. He points out that the Second Council of Constantinople and the First Council of Ephesus both condemned the position that two subsistences resulted from the Incarnation and anathematized anyone who denied that the Word was united to flesh in subsistence.
In Article 4, St. Thomas addresses the question of whether the Person of Christ was composite after the Incarnation. The first objection, St. Thomas addresses in the main body of his presentation as it is the primary consideration. In the second, St. Thomas notes that composition is not solely in parts but also in number. In the third, explains that not all composition requires homogeneous parts since animals are composed of soul and body, neither of which by itself is an animal. The first objection adheres to a view of the person of Christ prior to the Incarnation, as the Nature of the Word only. But following the Incarnation, Christ subsists in two natures: one subsistent being but different aspects of subsistence. So Christ is, after the Incarnation, a composite being.
In article 5, St. Thomas notes that the essence of a human being is for soul to be united in body. To objection 1, he points out that union of soul and body result in a person since they exist in themselves, but in Christ, they are joined to an existing person, so a new person need not result. In his response to objection 2, he notes that the human nature He assumed was of an individual, which isn’t common in the sense of something generalized and purely abstract, nor was the Damascene talking about a nature that came about after the union of human and Divine natures. Finally, he distinguishes between the effective principle of life (the Word) and the formal principle (the soul) and adds that the former cannot be the form of the body. As the essence of being human requires a soul to be united to a body, it could be no less in Christ. To claim such would be to diminish the humanity of Christ and lapse into heresy.
In article 6, St. Thomas addresses whether human nature was united to the Word accidentally. He responds to the objection that St. Paul referred Christ as being “in the habit found as a man” (Phillipians 2:7), and that habits are accidents. To this he replies that examples need not (and in fact should not) be similar in every way. Oddly, he doesn’t refer to his own argument on habits (II, 51, 1) in which he quite clearly says that some habits accrue to nature and not ass accidents (for example, knowledge as an operation of intellect). In the second objection, St. Thomas notes that something that is assumed into a complete subject is accidental only if it is not assumed into the same being. In response to the third objection, he notes that accident is divided against (distinct from?) substance and that substance can be either the nature or the hypostasis. A union taking place in a hypostasis, then, wouldn’t be an accidental union. Pointing out that this accidental union was part of the error of Nestorius and Theodore of Mopuestia, he points out that union by accident of various kinds was condemned by the second Council of Constantinople and that they confessed a union of the Word with flesh in one subsistence.
In article 7, St. Thomas addresses whether the union was created. In response to the first objection that nothing in God can change, he notes that the union is really more in our way of thinking since the creature is united to God with no change to God. To the second objection that the union should be judged in reference to the dignity of the Divine Person, he states that the union exists only in a created nature, hence, is a created being. To the third, that Man is called Creator is on account of the terminus being the Divine Person, not in the union itself. He states simply that the union came to exist in time rather than existing from all eternity and that it represents a change in relation between God and creature rather than a change in the Creator.
In article 8, St. Thomas deals with the question of whether union is the same as assumption. He dispenses fairly quickly with each objection: first, that union and assumption have different relations to the terminus or end, union addressing relation while assumption addresses action; second, that action and patient differ between assumption and union; and third, that assumption implies patient and agent, so is logically different from union or Incarnation. His answer clarifies that the Son of God assumes human nature, while God the Father unites the Son with human nature. So while the relationship is the same, the agency is clearly identified by the word “assumption” but not by “union.”
In article 9, St. Thomas deals with the question of whether the union of two natures in Christ is the greatest of all unions. He dispenses with the objections by noting that the unity of the Divine Person is greater than mere numerical unity due to the fact that it is uncreated and self-subsisting, and that it is the union in the Divine Person which gives the union pre-eminence over other unions. Each objection and reply essentially addresses this aspect.
In article 10, St. Thomas points out that accidental grace is a likeness of the Divinity in which men participate. However, in the Incarnation is no participation in likeness but is actual union, which is greater. Also, while habitual grace is in the soul only, the grace of being united to the Divine Person belongs body and soul to the whole human nature. Grace, he notes, can be understood as God bestowing something gratuitously but also as a free gift. Both ways can be seen in operation in the Incarnation: first, that God willed the Incarnation gratuitously and second, that the union was a free gift that was not preceded by any merits.
St. Thomas points out in article 11 that holy men could not have merited the Incarnation condignly as if it were something they justly deserved but only congruously because their love and devotion elicited such a response from God. In addition, he notes that Incarnation is the principle (agency) of grace, which is the principle of merit. Referring to Titus 3:5, he notes that we are not saved by our own works but by Christ’s mercy and through baptism.
In the final article of this question, St. Thomas notes that something can be termed natural in two ways: first, it can be from the essential, or second, it can be with a man from birth. While the grace of union was not natural in the first sense, it most certainly was natural in the second sense in that it came to Him by way of His Divine Nature from the moment of His conception.