Article 5 — Whether in Christ there is only one activity

Fifth, it is asked whether in Christ there is only one activity. (Parallel texts: ST III.19.1; In III Sent., d. 10, q. 1, a. 1, qa. 1, ad 3; d. 18, a. 1; SCG IV.36; On Truth, q. 20, a. 1, ad 2.) It seems that there is.

Obj. 1: For Dionysius says, when God was made man, he lived by a certain new activity of God and man. (Pseudo-Dionysius, Epistle 4, “Ad Gayum monachum” (PG 3:1071–72).) Now, there would not be a new activity of God and man unless the activity were one and the same for each of them. Therefore, in Christ there is one activity of God and of man.

Obj. 2: Furthermore, things that concur in the same activity do not make the activity different. But divinity and humanity in Christ concur in the same activity. For instance, the divine power and bodily touch concurred to cleanse the leper.

Obj. 3: Furthermore, an action proceeds from an agent through some principle of action, as heating proceeds from fire through warmth. Therefore, the multitude and unity of an action must be considered either from the part of the agent or from the part of the principle by which the agent acts. But the number of actions in Christ is not taken according to the principle by which the agent acts, because in this way there would be many more than two actions in Christ, according to the diversity of the soul’s powers. Therefore, it should be said that there is one action in Christ because of the one acting suppositum.

Obj. 4: Furthermore, a principal agent and a tool have one and the same action, as cutting is the action of the carpenter and the saw. But humanity in Christ was the tool of the divinity in Christ, as Damascene says in book 3. (John Damascene, On the Orthodox Faith, bk. 3, ch. 15 (PG 94:1059–60).) Therefore, the action of humanity and divinity in Christ is one and the same.

Obj. 5: Furthermore, it is of supposita to act. Now, in Christ there is no other suppositum than the eternal suppositum, of which it cannot be said that it acts through the power of human nature, because it would thus receive something from human nature, and have being and actuality through human nature. For everything acts insofar as it is being in act. Therefore, there is no action in Christ unless it occurs through the power of the divine nature. Therefore, there are not two actions in Christ according to the two natures, namely, the divine and the human.

Obj. 6: Furthermore, the suppositum is more joined to the divine nature than is the activity. But human nature in Christ does not have its own suppositum, because of its union to the divine. Therefore, much less does it have its own activity. Therefore, there are not two activities in Christ.

Obj. 7: Furthermore, activities are of one united thing; hence, the Philosopher says in On the Soul 1 that if someone says the soul understands, it is as if he said that it also weaves or builds. (Aristotle, On the Soul 1.4, 408b11–13.) But Christ is one person in whom humanity is conjoined with divinity. Therefore, there is only one activity in Christ.

Obj. 8: Furthermore, the first and principal activity of an intellectual nature is the very act of understanding. But understanding is not an activity passing outwards into exterior nature, but remaining in the agent itself. Now, it is of a suppositum to act. But in Christ there is only one uncreated suppositum, which is simple. Since, therefore, in one simple thing there cannot be two acts of understanding, it seems that there cannot be two intellectual activities in Christ.

Obj. 9: Furthermore, a thing’s activity follows upon its property. But, according to Damascene, the two natures in Christ share with each other their idioms, that is, their own properties, because of the suppositum’s unity. (John Damascene, On the Orthodox Faith, bk. 3, cc. 3–4 (PG 94:994–99).) Therefore, for the same reason, they share their activities; thus, there are not distinct activities according to the natures’ distinction.

Obj. 10: Furthermore, all the activities in one man are traced back to one first principle, namely, to the will, which moves all the other potencies to act. But similarly in Christ there is one first principle, namely, divinity, by which his humanity was moved; thus, humanity’s activities in him are traced back to divinity as to a first principle. Therefore, there is only one activity in Christ.

Obj. 11: Furthermore, just as the rational soul and the body are one man, so God and man are one Christ, (Athanasius, Athanasian Creed 10 (PG 28:1583).) as Athanasius says. But the activity of the human body or rational soul is called a human activity. Therefore, the activity of Christ’s divinity and humanity ought equally to be called “Christian” activity; and in this way, there will only be one activity in Christ, just as there is one Christ.

Obj. 12: Furthermore, every activity comes from some form or power. But the principal agent does not give any form or power to an instrument. Therefore, an instrument does not have any activity insofar as it is an instrument. But human nature in Christ was the tool of divinity, as Damascene says. (John Damascene, On the Orthodox Faith, bk. 3, ch. 15 (PG 94:1059).) Therefore, human nature in Christ does not have any activity. Therefore, there is only the activity of divinity in Christ.

Obj. 13: Furthermore, the action informs the agent. Now, in Christ there is only one suppositum, namely, the eternal one, which cannot be informed by a created activity. Therefore, because it is of a suppositum to act, it seems that there is no created activity in Christ; thus, there is only one uncreated activity.

Obj. 14: Furthermore, one thing has one activity. But Christ is one thing, simply speaking, as was said above. Therefore, there is only one activity in Christ.

On the contrary (1), this is what the sixth synod says, in the one Lord Jesus Christ, our true God, we indivisibly, inconvertibly, without confusion, and without separation, glorify two natural activities; this is the divine and the human activity. (Third Council of Constantinople (the sixth ecumenical council, 680–681 AD), “Exposition of Faith”; see Decrees of the Ecumenical Council, ed. Norman Tanner (London: Sheed and Ward, 1990), 1:128.)

Furthermore (2), in book 3, Damascene says, we say there are two actions in Jesus Christ the Lord: for he has the divine action as consubstantial with the Father, and the action of human nature as the man he has been made. (John Damascene, On the Orthodox Faith, bk. 3, ch. 15 (PG 94:1045–47); see also bk. 3, cc. 11, 14 (PG 94:1023–27, 1034–46); Maximus the Confessor, Disputations with Pyrrhus, PG 91:342–50.)

Furthermore (3), just as in the Trinity there is one nature in three persons, so in Christ there are two natures in one person. But the whole Trinity has one activity because it has one nature. Therefore, Christ has two activities because of his two natures.

Furthermore (4), Boethius says in On the Two Natures that nature is what can act and be acted upon; (Boethius, On the Person and the Two Natures: A Treatise Against Eutyches and Nestorius, ch. 1 (PL 64:1341).) thus, action follows upon nature. But there are two natures in Christ. Therefore, there are also two actions.

Furthermore (5), activity follows upon power, but power follows upon the essence, which is the thing’s nature. Therefore, where there are two natures, there are two powers, and consequently two activities. Thus, there is not only one activity in Christ but two.

I answer that an action’s unity and plurality can be thought of in two ways.

One way is from the perspective of the acting subject. In this way, the action’s unity or plurality is considered according to number. This is just as any other accident has numerical unity or plurality from the subject’s perspective. For this is how Socrates’s sight or hearing is different in number from Plato’s sight or hearing.

In another way, we can consider an action’s unity or plurality from the perspective of the principle by which the agent acts; and in this way, the action is said to be one or many according to species. Thus, sight and hearing are activities differing in species.

Now, an action comes from an agent according to the account of the power by which it acts. Nor is it a problem that actions receive their species from their objects, because determinate powers look toward determinate objects. Nevertheless, we should consider that, if the power which is the principle of an action should be moved by another, higher power, the activity which comes from it is not only an action but also a passion, namely, insofar as it comes from a power which is moved by a higher one. Now, in man all the powers of the sensitive part are in a way moved by the will as by a certain first principle. Thus, to hear, to see, to imagine, to desire, and to be angry are not only actions, but also certain passions coming from the will’s motion, namely, insofar as a man goes towards them from his own will. Therefore, though in one man there seem to be many actions differing in species according to diverse potencies and habits, nevertheless, because they all come from the will’s one first action, we say there is one action of one man. In this way, if one craftsman were to work with many tools, we would say one man has one activity.

Because of this, therefore, some have asserted that there is only one activity in Christ, since in him human nature is subject to and moved by the divine activity. Thus, human nature’s action has more the account of a passion in comparison with the divine. Hence, because of the unity of the divine action, they said that there is only one action in Christ.

But this was irrationally said for two reasons.

First, this was irrationally said because some powers do not have ownership of their own act in such a way that they are moved by a superior to the extent that they themselves do not act but are more acted upon. Hence, the Philosopher says in Ethics 4 that a sense is not the principle of any action. (Aristotle, Nicomachean Ethics 2.2, 1104a27–b1; 6.2, 1139a19–20.) But a power which does have ownership of its own act, namely, the will, is moved by something higher, namely, God, in such a way that it is not only acted upon but also acts. Since, according to his human nature, Christ has the will’s created potency, just as he has a created intellect—because he lacks nothing pertaining to the perfection of human nature—consequently, the motion of the human will in Christ will be an action and not merely a passion. Otherwise, he could not merit according to human nature.

Second, it was irrationally said because a thing’s activity has species and unity from the first principle pertaining to the same nature. Thus, the will, from which all human actions have unity, is a certain intrinsic principle of human nature. But no actions have unity by being traced back to some first principle of a different nature; otherwise, it would follow that all things have one action because there is one first principle moving everything, namely, God. In this way, therefore, even if the human nature in Christ is moved by the divine, nevertheless, there must still be two actions because the two natures are distinct.

Therefore, from the position that there is one action in Christ, it follows that he would have only one nature and one will. Thus, this position is tantamount to the heresy condemned by the sixth synod. (Third Council of Constantinople, “Exposition of Faith.”)

Reply Obj. 1: Christ’s activity according to humanity is called “theandric,” that is, “God-manly,” insofar as Christ’s humanity was working in the divine power. Through this, humanity’s action was salvific, like an instrument which works in the agent’s power. To this extent is it called “a new-made action,” because Christ’s humanity is made anew to be the instrument of divinity conjoined in unity of person—but it is not said in such a way that there be one composite from two actions.

Reply Obj. 2: Divinity and humanity in Christ concurred in the same action without confusion. For each nature, as Pope Leo says in a letter, did what is proper to it with the communion of the other nature. (Leo the Great, Letter 28, “Ad Flavianum,” ch. 4 (PL 54:767); see also Decrees of the Ecumenical Council, 1:79.) For instance, the divine power cleansed the leper together with the touch of the human body, which drew its efficacy from the divine power.

Reply Obj. 3: In Christ, all actions pertaining to human nature are reduced into one action on account of the unity of the connatural principle, namely, the will. But this is not the case with the humanity and divinity, as has been said.

Reply Obj. 4: Human nature in Christ is not the kind of instrument that can be only acted upon, but the kind that is also a principle of action, insofar as it has ownership of its own act.

Reply Obj. 5: Something acts by another’s power in two ways: in one way, insofar as it is moved by that power, as natural heat works by the power of the soul; in another way, insofar as an agent uses the power of an instrument, as the soul sees by the power of the eye. And the eternal suppositum acts in this way by the power of human nature.

Reply Obj. 6: A suppositum is what is distinct from other things; thus, it would conflict with the personal union were human nature to have a suppositum of itself. But “activity” does not carry with it the account of any distinction, and thus the argument does not follow.

Reply Obj. 7: Activities are conjoined from many things appropriate to one nature. But the conjunction of divinity and humanity in Christ is not like this. Hence, the argument does not follow.

Reply Obj. 8: It is intrinsic to the intellect to understand itself. But there are two intellects in Christ, namely, the created and the uncreated one. Thus, there are also two acts of understanding there.

Reply Obj. 9: In Christ, there is communication of idioms. This is not because there is any confusion of natural properties, but because the properties of each nature are said of the same suppositum. It is the same with the communication of activities, because it is the same suppositum to which the same activity is attributed, divine and human.

Reply Obj. 10: The will is a principle connatural to the other potencies of the soul, but divinity is not connatural to humanity; hence, the argument is not similar.

Reply Obj. 11: Athanasius applies that simile to the unity of person, not to the unity of nature. For the body and soul come together into one person and one nature; thus, we say there is one human activity. Now, the divine and human nature come together into one person, but not into one nature, and, consequently, not into one action.

Reply Obj. 12: An agent does not always give the instrument a new form or power resting in itself. Nevertheless, the instrument, insofar as it is moved by the agent, follows a certain intentional power through what flows from the agent, passing through the instrument into the effect.

Reply Obj. 13: Just as vision informs a man by means of the eye, so also does created action inform the eternal suppositum by means of human nature.

Reply Obj. 14: Christ is simply one because of the suppositum, but, nevertheless, there are two natures in him. Hence, Christ is one agent, but there are two actions in him.