Of the Unity of Christ's Operation

I answer that, As was said above (Q. 18, A. 1), the aforesaid heretics who placed one will in Christ placed one operation in Christ. Now in order better to understand their erroneous opinion, we must bear in mind that wherever there are several mutually ordained agents, the inferior is moved by the superior, as in man the body is moved by the soul and the lower powers by the reason. And thus the actions and movements of the inferior principle are things operated rather than operations. Now what pertains to the highest principle is properly the operation; thus we say of man that to walk, which belongs to the feet, and to touch, which belongs to the hand, are things operated by the man—one of which is operated by the soul through the feet, the other through the hands. And because it is the same soul that operates in both cases, there is only one indifferent operation, on the part of the thing operating, which is the first moving principle; but difference is found on the part of what is operated. Now, as in a mere man the body is moved by the soul, and the sensitive by the rational appetite, so in the Lord Jesus Christ the human nature is moved and ruled by the Divine. Hence they said that there is one indifferent operation on the part of the Godhead operating, but divers things operated, inasmuch as the Godhead of Christ did one thing by Itself, as to uphold all things by the word of His power—and another thing by His human nature, as to walk in body. Hence the Sixth Council [Third Council of Constantinople, Act. 10] quotes the words of Severus the heretic, who said: "What things were done and wrought by the one Christ, differ greatly; for some are becoming to God, and some are human, as to walk bodily on the earth is indeed human, but to give hale steps to sickly limbs, wholly unable to walk on the ground, is becoming to God. Yet one, i.e. the Incarnate Word, wrought one and the other—neither was this from one nature, and that from another; nor can we justly affirm that because there are distinct things operated there are therefore two operating natures and forms."

But herein they were deceived, for what is moved by another has a twofold action—one which it has from its own form—the other, which it has inasmuch as it is moved by another; thus the operation of an axe of itself is to cleave; but inasmuch as it is moved by the craftsman, its operation is to make benches. Hence the operation which belongs to a thing by its form is proper to it, nor does it belong to the mover, except in so far as he makes use of this kind of thing for his work: thus to heat is the proper operation of fire, but not of a smith, except in so far as he makes use of fire for heating iron. But the operation which belongs to the thing, as moved by another, is not distinct from the operation of the mover; thus to make a bench is not the work of the axe independently of the workman. Hence, wheresoever the mover and the moved have different forms or operative faculties, there must the operation of the mover and the proper operation of the moved be distinct; although the moved shares in the operation of the mover, and the mover makes use of the operation of the moved, and, consequently, each acts in communion with the other.

Therefore in Christ the human nature has its proper form and power whereby it acts; and so has the Divine. Hence the human nature has its proper operation distinct from the Divine, and conversely. Nevertheless, the Divine Nature makes use of the operation of the human nature, as of the operation of its instrument; and in the same way the human nature shares in the operation of the Divine Nature, as an instrument shares in the operation of the principal agent. And this is what Pope Leo says (Ep. ad Flavian. xxviii): "Both forms" (i.e. both the Divine and the human nature in Christ) "do what is proper to each in union with the other, i.e. the Word operates what belongs to the Word, and the flesh carries out what belongs to flesh."

But if there were only one operation of the Godhead and manhood in Christ, it would be necessary to say either that the human nature had not its proper form and power (for this could not possibly be said of the Divine), whence it would follow that in Christ there was only the Divine operation; or it would be necessary to say that from the Divine and human power there was made up one power. Now both of these are impossible. For by the first the human nature in Christ is supposed to be imperfect; and by the second a confusion of the natures is supposed. Hence it is with reason that the Sixth Council (Act. 18) condemned this opinion, and decreed as follows: "We confess two natural, indivisible, unconvertible, unconfused, and inseparable operations in the same Lord Jesus Christ our true God"; i.e. the Divine operation and the human operation.

I answer that, Since it is by his reason that man is what he is; that operation is called human simply, which proceeds from the reason through the will, which is the rational appetite. Now if there is any operation in man which does not proceed from the reason and the will, it is not simply a human operation, but belongs to man by reason of some part of human nature—sometimes by reason of the nature of elementary bodies, as to be borne downwards—sometimes by reason of the force of the vegetative soul, as to be nourished, and to grow—sometimes by reason of the sensitive part, as to see and hear, to imagine and remember, to desire and to be angry. Now between these operations there is a difference. For the operations of the sensitive soul are to some extent obedient to reason, and consequently they are somewhat rational and human inasmuch as they obey reason, as is clear from the Philosopher (Ethic. i, 13). But the operations that spring from the vegetative soul, or from the nature of elemental bodies, are not subject to reason; consequently they are nowise rational; nor simply human, but only as regards a part of human nature. Now it was said (A. 1) that when a subordinate agent acts by its own form, the operations of the inferior and of the superior agent are distinct; but when the inferior agent acts only as moved by the superior agent, then the operation of the superior and the inferior agent is one.

And hence in every mere man the operations of the elemental body and of the vegetative soul are distinct from the will's operation, which is properly human; so likewise the operations of the sensitive soul inasmuch as it is not moved by reason; but inasmuch as it is moved by reason, the operations of the sensitive and the rational part are the same. Now there is but one operation of the rational part if we consider the principle of the operation, which is the reason and the will; but the operations are many if we consider their relationship to various objects. And there were some who called this a diversity of things operated rather than of operations, judging the unity of the operation solely from the operative principle. And it is in this respect that we are now considering the unity and plurality of operations in Christ.

Hence in every mere man there is but one operation, which is properly called human; but besides this there are in a mere man certain other operations, which are not strictly human, as was said above. But in the Man Jesus Christ there was no motion of the sensitive part which was not ordered by reason. Even the natural and bodily operations pertained in some respects to His will, inasmuch as it was His will "that His flesh should do and suffer what belonged to it," as stated above (Q. 18, A. 5). Much more, therefore, is there one operation in Christ, than in any other man whatsoever.

I answer that, To have any good thing of oneself is more excellent than to have it from another, for "what is of itself a cause is always more excellent than what is a cause through another," as is said Phys. viii, 5. Now a thing is said to have, of itself, that of which it is to some extent the cause. But of whatever good we possess the first cause by authority is God; and in this way no creature has any good of itself, according to 1 Cor. 4:7: "What hast thou that thou hast not received?" Nevertheless, in a secondary manner anyone may be a cause, to himself, of having certain good things, inasmuch as he cooperates with God in the matter, and thus whoever has anything by his own merit has it, in a manner, of himself. Hence it is better to have a thing by merit than without merit.

Now since all perfection and greatness must be attributed to Christ, consequently He must have by merit what others have by merit; unless it be of such a nature that its want would detract from Christ's dignity and perfection more than would accrue to Him by merit. Hence He merited neither grace nor knowledge nor the beatitude of His soul, nor the Godhead, because, since merit regards only what is not yet possessed, it would be necessary that Christ should have been without these at some time; and to be without them would have diminished Christ's dignity more than His merit would have increased it. But the glory of the body, and the like, are less than the dignity of meriting, which pertains to the virtue of charity. Hence we must say that Christ had, by merit, the glory of His body and whatever pertained to His outward excellence, as His Ascension, veneration, and the rest. And thus it is clear that He could merit for Himself.

I answer that, As stated above (Q. 8, AA. 1, 5), grace was in Christ not merely as in an individual, but also as in the Head of the whole Church, to Whom all are united, as members to a head, who constitute one mystical person. And hence it is that Christ's merit extends to others inasmuch as they are His members; even as in a man the action of the head reaches in a manner to all his members, since it perceives not merely for itself alone, but for all the members.