Chapter 211 — That in Christ there is only one suppositum and only one person

Accordingly, we must say that in Christ there is not only one person of God and man, but also that there is but one suppositum and one hypostasis. There is not, however, only one nature, but two natures.

To see that this is so, we have to consider that the names ‘person,’ ‘hypostasis,’ and ‘suppositum’ signify a certain whole. We cannot say that a hand or flesh or any of the other parts is a person or a hypostasis or a suppositum; but this whole, which is this man, is such. But names that are common to individuals in the line of substance and accident, such as ‘individual’ and ‘singular,’ can be applied both to a whole and to its parts. Parts have something in common with accidents in the sense that they do not exist by themselves, but inhere in other things, although in a different way. We can say, therefore, that the hand of Socrates or Plato is a certain individual or singular thing, even though it is not a hypostasis or a suppositum or a person.

Furthermore, we should note that a combination of various ingredients, considered just in itself, sometimes constitutes an integral whole, which same combination does not constitute an integral whole in another being because of the addition of some other component. Thus in a stone the combination of the four elements constitutes an integral whole; and so the object composed of the elements can, in the stone, be called a suppositum or hypostasis, which is this stone. It cannot, of course, be called a person, because it is not a hypostasis endowed with rational nature. But the combination of elements in an animal constitutes not an integral whole, but only a part, namely, the body. Something else must be added to make up the complete animal, and this is the soul. Hence the combination of elements in an animal does not constitute a suppositum or hypostasis; rather, this whole animal is the hypostasis or suppositum. Nevertheless, the combination of the elements is not, on this account, any less effectual in an animal than in a stone, but is rather more so, because it is ordained to the formation of a nobler being.

In all other men, therefore, the union of soul and body constitutes a hypostasis and suppositum, because in their case the hypostasis or suppositum is nothing else but these two components. But in our Lord Jesus Christ, besides soul and body, a third substance enters in, namely, divinity. In him, therefore, the composite of body and soul is not a separate suppositum or hypostasis, nor is it a person. The suppositum, hypostasis, or person is that which is made up of three substances: namely, the body, the soul, and the divinity. And thus in Christ, just as there is but one person, so there is but one suppositum and one hypostasis.

But the way his soul is joined to his body differs from the way his divinity is united to both. His soul is joined the body as being its form, so that one nature, which is called human nature, is composed of these two. But divinity does not come to the soul and body as a form or as a part; this is against the very concept of divine perfection. Therefore, the divinity and the soul and the body do not constitute one nature; but the divine nature, complete in itself and existing in its purity, united to itself the human nature composed of soul and body in a way that is incomprehensible and indescribable. This called for an exercise of God’s infinite power. For we see that the stronger an agent is, the more closely he connects to himself an instrument to carry out an undertaking. Therefore, as the divine power is infinite and incomprehensible because of its infinity, so too the way God united Christ’s human nature to himself (as a sort of organ for accomplishing man’s salvation) is beyond human expression and surpasses every other union of God with creation.

We pointed out above that person, hypostasis, and suppositum signify an integral whole. Hence if the divine nature in Christ had the function of a part, like the soul in the composition of a man, and were not something whole, then the one person of Christ would not be accounted for by the divine nature alone, but would be a certain composite of three elements, just as in man the person, hypostasis, and suppositum is what is constituted of soul and body. However, since the divine nature is an integral whole that took human nature to itself by an ineffable union, the person is accounted for by the divine nature, as also is the hypostasis and suppositum. Yet the soul and body are drawn to the personhood of the divine person, such that the person of the Son of God is also the person and the hypostasis and suppositum of the Son of man.

Some sort of example of this can be found in creatures. Thus subject and accident are not united in such a way that some third thing is formed from them. In a union of this kind, the subject does not have the function of a part, but is an integral whole, which is a person, hypostasis, and suppositum. But the accident is drawn to the personhood of the subject, so that the person of the man and of the color of whiteness is one and the same, and the hypostasis or suppositum is likewise the same. In a somewhat similar fashion the person, hypostasis, and suppositum of the Son of God is the person, hypostasis, and suppositum of the human nature in Christ. Influenced by comparisons of this sort, some theologians went so far as to say that the human nature in Christ deteriorates into an accident and is accidentally united to the Son of God; they were unable to discriminate between literal truth and likeness.

Therefore, the foregoing exposition makes it clear that there is no other person in Christ but the eternal person, who is the person of the Son of God. Nor is there any other hypostasis or suppositum. Hence when we say, ‘this man,’ pointing to Christ, we mean the eternal suppositum. Nevertheless, the name ‘man’ is not for that reason predicated equivocally of Christ and of other men. Equivocation does not follow diversity of supposition, but follows diversity of signification. The name of man, as attributed to Peter and to Christ, signifies the same thing, namely, human nature. But it does not have the same supposition; for in the one case it takes the eternal suppositum of the Son of God as what underlies, while in the other case it takes a created suppositum as what underlies.

Since, however, we can predicate of a suppositum of some nature all that is proper to that nature of which it is the suppositum, and since in Christ the suppositum of the human nature is the same as the suppositum of the divine nature, it is evident that everything belonging to the divine nature and everything belonging to the human nature can be predicated indifferently of this suppositum, which is the suppositum of both natures. This is true both when the name we use signifies the divine nature or person, and when it signifies the human nature. We can say, for example, that the Son of God is eternal, and that the Son of God was born of the Virgin. Likewise we can say that this man is God, that he created the stars, and that he was born, died, and was buried.

What is predicated of a suppositum, is predicated of it according to some form or matter. Thus Socrates is white according to the whiteness of his skin and is rational according to his soul. But, as we pointed out in the beginning of this chapter, in Christ there are two natures and one suppositum. Therefore, if reference is made to the suppositum, human and divine things are to be predicated indifferently of Christ. Yet we must discern in what respect each thing is predicated; that is, divine attributes are predicated of Christ according to his divine nature, and human attributes are predicated of him according to his human nature.