From Emile Mersch's The Theology of the Mystical Body,

pages 202-216



Accordingly we must focus attention on Christ's humanity. All the divine decrees that sanctify the human race by making of it an organism of grace are included in the decree that willed the humanity of Christ, or rather are basically realized in the very way that humanity exists. It is God's own humanity, as the sacred document of Chalcedon proclaims.

Following in the footsteps of the holy Fathers, we all with one accord teach belief in one and the same Son, our Lord Jesus Christ. We declare that He is perfect in divinity and perfect in humanity, that He is true God and true man, composed of rational soul and body, that He is consubstantial with the Father in divine nature and consubstantial with us in human nature, "in all things like as we are, without sin" [Heb. 4:15]; that before all ages He was born of the Father according to His divine nature, and in these latter days was born of the Virgin Mary, Mother of God, for our sake and for our salvation, according to His human nature; that one and the same Christ, the only-begotten Son our Lord, must be acknowledged as existing in two natures unconfusedly, unchangeably, undividedly, inseparably, with no suppression of the distinction between the natures on account of the union, but rather with the individuality of each nature safeguarded and coming together in one person and subsistence, not parted or divided into two persons, but one and the same Son and only-begotten God the Word, Jesus Christ the Lord. (21) (Denz., 148.)

"One and the same": the Council repeats the words with majestic insistence; this man who is Christ is truly, strictly, identically God. The whole of Christianity is there. Even if one holds, contrary to St. Thomas, that the human nature in Christ has its own proper existence, one has to acknowledge or rather proclaim that this existence is incomplete and receives its ultimate reality only by being united to the divine existence. There are not two Christs, there is only one Christ; and in this Christ, consequently, the man is God, wholly God. "The whole God is man, and the whole man is God; whatever belongs to the humanity, God the man makes His own; and whatever belongs to God, the man God possesses." (22) (St. Gelasius I, tomus Necessarium (Denz., 168).) "Just as God the Word, by taking to Himself what belongs to man, is man, so the assumed man, by receiving what belongs to God, cannot be other than God." (23) (Libellus Leporii, Cavallera, Thesaurus doctrinae catholicae, 669.)

This intimate union, this rigorous unity of person, implies a union in properties, a communication of idioms. "He who is true God is likewise true man; and although the lowliness of man and the sublimity of Godhead are conjoined, there is nothing contradictory in this unity. For just as God is not changed by His mercy, so neither is His humanity absorbed by divine majesty. Each of these natures, though in union with the other, performs actions proper to itself: the Word does that which belongs to the Word, and the flesh does that which belongs to the flesh." (24) (St. Leo I, Tomus ad Flavianum, 4 (Denz., 144).)

This interchange of properties does not involve their fusing; the natures remain absolutely distinct, and so do the properties. They are united in the person, not in the natures; and even when the person is designated by a term that represents only one nature, we can apply to the person the predicates of the other nature. This interchange is something truly ontological, and is not merely verbal or logical. The person is truly both man and God, and so the union of the two sets of properties is truly real in Him.

The divinity can in no way be affected by this union in the person; the divinity and its attributes are immutability itself. But the humanity is necessarily affected. To correspond to something real and objective, the communication of idioms has to correspond to something in the human nature. But this something in the human nature must be human, because the nature itself is human, and whatever is received, is received according to the capacity of the recipient. In the human nature, answering to something in it and fitted to it, this will be, not the predicates themselves, for that is utterly impossible, but the reaction and effect of these predicates, the union and adapting of the human nature to them, something that necessarily has some relation and proportion to them. This communication therefore, as we may term it, is not the communication of idioms properly so called, but is its result and, as it were, its prolongation in the interior of the human nature.

St. Robert Bellarmine, whom we have been following and commenting in this explanation, expresses the latter point as follows. "The Catholic teaching involves two things," he says. The first alone interests us at present.

First, many created and infused gifts come to Christ's humanity from the hypostatic union, such as a most excellent grace and other perfections of the kind, which are not attributes of the Godhead except by a sort of participation, in the way in which we share in God's attributes through created qualities, although less fully than Christ's humanity shares in them. The communication of idioms does not consist in such gifts; for that communication is mutual, whereas the communication of these gifts is not mutual, since nothing accrues to the Godhead. (25) (Controversiae, 1I, De Christo capite totius Ecclesiae, III, 9.)

This sharing in the attributes of the Godhead by the humanity of Christ must be determined more accurately. Theological treatises deal with this participation at some length and demonstrate its existence when they discuss the sanctifying grace Christ's humanity had to possess. Thus they come directly to the essential point. For our part, we wish to approach this subject less precipitately and to treat of it only at the end.

If this participation is Godlike and if it is a grace for the reason that it adapts the recipient to God, it is human because it is produced in a human nature and because, in its Godlike elevation, it is a more perfect way of existing for the human nature. Furthermore, it is conditioned by the limitations and potentialities – we do not say the virtualities – of the human essence. From the standpoint of the human nature and in the view of men who study the matter, the participation must therefore, in the first instance, appear as something human.

Undoubtedly the transcendental aspect that makes it a divinization and the human aspect that makes it an exaltation of the human nature are strictly inseparable; only the strict unity of the person with the two natures accounts for its existence. Yet the two aspects are distinct, with a distinction derived from that of the natures which are united. In these pages we wish to begin with the human aspect. Accordingly what is usually presented in theology as a divinization appears to be primarily a realization of the ultimate perfections human nature is capable of and, if we may say so, a transcendent "humanization."

This transcendence, however, becomes more and more the center of attention, and we shall find it increasingly difficult not to speak of divinization. When a drop of water reflects the brilliance of the sun, it is hard to see only water in it rather than the sun.

As is clear, the choice concerns no more than a detail in method and procedure. The procedure is imposed by the line of thought which the authentic teaching suggests. In considering Christ's humanity in itself, but as perfected by the hypostatic union, we may hope to gain an insight into the mystic totality of this humanity, or in other words, into the mystical body.

This detail in method justifies and even requires, on principle, corresponding details in formulas and points of view. When the same landscapes are looked at from different angles they appear different, precisely because they are the same. Yet the basic identity can be perceived. The line of thought, however different it may be, will issue in quite traditional theses, and in the course of the advance various crossroads that may not be overlooked will indicate junctions.

In the meantime the detour, if detour it be, will enable us to judge more clearly the extent to which the Incarnation and Christianity are human, and the extent to which grace, divinization, and the Gospel lay hold of man as man and become his chief necessity.


The human nature of Christ, being the human nature of God, is evidently raised to a supernatural perfection. This perfection consists primarily and radically in the very subsistence imparted to it. As such, the perfection is not accidental or natural or essential, any more than the hypostatic union is. (26) (St. Thomas, Summa, IIIa, q.2, a.6.) It is substantial, or rather subsistential.

But this first perfection necessarily leads to a perfection that is accidental and intrinsic to the assumed human nature. For, since the union is accomplished in the person, the natures remain distinct, and the human nature remains distinct from the subsistence in which it subsists. Yet it does subsist there, truly, ontologically, and intrinsically; indeed, once the union takes place, this fact is the deepest and most intimate reality in it. Therefore the way the human nature exists is other than it would be apart from this subsistence.

Such is the perfection we are speaking of at present. It is a perfecting of a human nature and is therefore something human; but it is something by which a human nature possesses subsistence in God. It is a mutatio, says St. Thomas, (27) (Summa, la, q.43, a.2 ad 2; IIIa, q.2, a.7 et ad 1; a.8; Contra Gent., IV, 49) a change as compared with what the human nature would be were it not thus perfected, not as compared with a prior state that never existed; he also calls it a perfectio, (28) (In I Sent., d. 14, q. 1, a. 1 ad 2.) or, following the lead of St. Augustine, a melioratio, an amelioration. (29) (Summa, IIIa, q.2, a.6 ad I; d. St. Augustine, De diversis quaestionzbus 8] (PL, XL, 8S). Here we must rid ourselves of certain conceptions and imaginations which, by reducing this perfection to nothing, reduce the Incarnation to nothing. Such is a certain juridical cast of mind that would reduce this perfection to a right, a condition, a patent of nobility. A divine decree, in this view, would have conferred on the assumed human nature a sort of dignity in virtue of which God would consider it as His own and would enjoin on creatures the duty to regard it as such. Or again, a kind of gratuitous transfer and grant would have given to this human nature a title to divine attributes, the right to lay claim to supreme honors, the power to reign over all things, the ability to perform actions of infinite value and to make decisions having eternal ratification.

Complicated juridical theories of this kind do not compel us to acknowledge any ontological, intrinsic perfecting of Christ's human nature. Indeed, as they stand, they do not even allow us to perceive any reality in the Incarnation. We are given nothing but certain acts of God that remain quite transcendent with respect to all finite being, including the human nature which is said to be assumed; and we do not see how this human nature exists otherwise than it would without any assumption.

We are told that it has a right, an ownership with reference to divine subsistence. But what meaning can such an assurance have? A right supposes a certain superiority. The Word is not a thing that can be appropriated. Subsistence does not consist in having, but in being. Moreover, rights reside in persons; the right conferred by the Incarnation would be a right over the Word given to the Word. In brief, all this externalizing, by identifying the Incarnation with shallow considerations and relations that are mere juridical entities, makes of it a superficial thing lacking solid truth, thus expelling it in some way from the assumed human nature and, by that very fact, from itself.

We beg to be excused for having set forth this juridical conception at such length. But perhaps our effort has some value in arousing attention to the matter. No one, of course, would admit the theory as we have put it; but aspects of it may easily worm their way into the mind that is accustomed to think in such a manner and to seek clarity of understanding in the realm of such ideas.

Assuredly a divine decree was necessary: Christianity, like creation, has no other origin. But divine decrees are efficacious. If God wishes a human nature to be His, it will be His, throughout its whole being, ontologically and intrinsically; for God attains being as being.

The divine action was efficacious. It consisted in an assumption, an attracting to the Word, a joining to a divine person, a union, an adhering, an elevation to God, a unifying action, as theologians variously put it. All this, surely, and nothing but this. But to be this, the divine action has to be received in the human nature, and quidquid recipitur, recipitur ad modum recipientis; it has to be received according to the capacity of the human nature. In the human nature, therefore, there will be something human, something called forth by the divine action, something that will be, so to speak, the received assumption, the passive attraction and joining, the passio unitiva corresponding to the actio unitiva; it will be the terminatio ad Filium.

The question is to determine what this something consists in; and this, we believe, is the great question in all theology. Theologians grapple with the problem chiefly in their commentaries on the Summa, IIIa, q. 2, a. 6-8.

We shall not follow them in their investigations; but at least we must insist on the truth that this attracting, this adhering, may not be envisaged as a sort of riveting or welding or dovetailing. This truth is quite evident; yet we shall have to be continually on our guard against the encroachments of the imagination. Nor may we fancy that some third entity slips in between the finite and the infinite, like cement or solder, to attach one to the other. Such is the connecting medium in which some Scholastics have sought the explanation of the Incarnation; but St. Thomas has triumphantly rejected it. It calls to mind the animal spirits that connect body and soul in Cartesian psychology. What could be a middle term between the finite and the infinite? And what would become of the union with God, if the human nature is only joined to this middle term?

The perfecting we wish to speak of is not and cannot be in the order of efficient causality that brings about the union, however slight the efficient causality may be; the union would in that case lose its transcendence. The perfection does not predispose to the union, does not prepare for it, does not facilitate it. The perfection comes into being through the union, not vice versa; it is the union that explains the perfection, not the perfection that accounts for the union.

We may say that the perfecting causes the assumed human nature to be the human nature of God and that it adapts the human nature for the union. It does so, however, not in the way of an efficient cause, but in the way of a quasi-formal cause. The union alone, the assumption alone accounts for everything. However, since the union is a work of omnipotence, it necessarily has an effect; so necessarily that, if this effect were not produced, the union would not take place. In the same way, when a rock falls on a cushion, the hollow produced in the cushion is the effect of the pressure of the rock, an effect so inevitable that, if it were not produced, the reason would be that the rock had not fallen, and an effect so immediate that it is but the passive aspect of the active pressure; it is an inseparable effect, an effect that accompanies the cause, but nevertheless an effect that in itself is not the cause.

Such is the perfection in question. It is not the assumption and it is not the subsistence of the Word; it is their result in the human nature. It is the accidental amelioration whereby the human nature in its own way – for it has no other – is truly constituted, in its interior, the human nature assumed by the Word, with an assumption that in itself is not accidental but substantial and subsistential; an amelioration that is in no sense an element or a determinant of the divine initiative, but that makes the human nature the beneficiary of that initiative.

Scholasticism insists that a thing truly is what it is by a form or by an act; otherwise it would be what it is by not being at all. Whatever it may be, it must realize in itself that by which it is. A form is required if a determination of being is in question; an act is required if being itself is in question. Since the assumed human nature is the human nature of God, it must have within itself that which makes it such. Undoubtedly, as we cannot repeat too often, it is such in the first place through the pure Act itself, which alone can be the principle of such a way of existing.

But the pure Act cannot itself be a change or an amelioration of a finite nature; it cannot be that which constitutes this nature, within itself, the beneficiary of the assumption. Although the Word's subsistence alone is the subsistence of the assumed human nature, the sole id quo subsistit, it cannot be the possession of this subsistence by the human nature and the latter's attachment thereto; for in the human nature that is something human. The personal unity of the God-man, which makes it absolutely impossible for the human nature to have the slightest personality of its own, nevertheless requires with no less absolute necessity that the human nature should have within itself that which establishes it truly and intrinsically in the unique personality of the Word.

With reference to the assumption itself, this factor will be neither a cause nor an intermediary, but an effect, and an effect so immediate and formal that it finds lodging only in the assumed nature, as assumed. It is the first effect of the assumption, the characteristic and formal effect, the effect produced in the only place where an effect can be produced, for the Godhead is absolutely immutable. We cannot really and seriously think of an attraction exerted by the Word, of a joining, a union, without having recourse to a corresponding change and perfection caused in the assumed nature by the union itself. It is a perfection that cannot exist or endure except in and through the union, and that expresses and actualizes the union in the nature receiving it, or rather actualizes according to the union, in the union, and through the union the nature which subsists only in the union. Consequently we can no longer think of this nature as it is in itself in virtue of the union without thinking of God to whom it is united.

Although the perfection in question is the product of the union and is received exclusively in the human nature, this does not mean that the human nature was wholly passive in receiving it. On the contrary, the human nature had to be intensely active in receiving it, even though this activity itself was received. The reception had to be accomplished in the deepest center, the very root of the nature, and hence had to be brought about in a suitable way, that is, through an act of immanent spontaneity; to lay hold of the human nature as it is, the reception had to take place in that nature's inner source of activity, which is liberty. Hence we should say that it implies an act of unreserved self-donation, consecration, and love, which is, as it were, a consent to the union. But the consent was given to the union as accomplished, and was called forth by the power of this union. The union raised the consent to the height at which the union itself was effected, for without such consent the union would in a sense be violent and would not be human in its term. Apparently we have to go so far as to say that the consent was elevated to such a height as, in its own way, to cause the union. It did not, of course, effect the union, but was needed in order that the union might be fully accomplished in facto esse. We can hardly exaggerate in asserting how perpetual and complete this consent to God had to be, and how intense a charity, a self-donation to God, to the work of God, and to all men, this immediate cooperation with infinite charity involved.

This consent had to be an enduring disposition of a special kind, expressing what was most deeply rooted in the human love that subsisted in the donation of God. It is expressed in a multiplicity of distinct acts, as is the case with all human acts; but through it they are all in communication, in the same humanity and the same divine personality. (30) (We shall have occasion to come back to this disposition more than once, especially in connection with actual grace.)


We must next point out the greatness of this perfection. Simply to be, for any creature, is not nothing, but is everything that the creature is. What, then, must it mean to be God? For that is what is in question for the man who is Christ: not to be with God or penetrated by God or bound to God, but to be God, literally, in person.

God is the transcendent totality of being, the hypostatic union is the closest of all possible unions, and the Incarnation is the unparalleled work in which God goes to the limit of His love and of man's capacity; and all this, at one stroke, bursts forth on the unresisting being that is the creature in the presence of the Creator. The entire being of the creature could not but be profoundly affected. God becomes the creature's personality. And personality is the innermost center of a being, and God is most efficacious in His action. What will be produced by such an agent, that penetrates so deeply? United to fire, a log becomes a torch; united to God in unity of person, what will human nature become?

The Incarnation produces nothing new in the Word. The whole of the new effect called forth is in the assumed human nature, (31) (St. Thomas, Summa, III a, q. I, a. I ad I.) and through it, in other human natures, while remaining in the assumed human nature. This new effect is, in the first place, the subsistence of the human nature in the Word. But to subsist in the Word, it needs something else than the subsistence of the Word Himself, who exists independently of the Incarnation. It needs, as the one new reality, the change we have been speaking of, the change that places the human nature in possession of such a subsistence.

The purpose of this change is to adapt the human nature to such a reception, so that it may be truly what God makes it to be; to establish in it a "quasi-form or a quasi-act that corresponds, in the human nature, to the elevation coming from God and in God; to be, in the object affected by the Incarnation, the passio or quasi-passio in which the actio that is the Incarnation terminates; to place this human nature in the state of being and acting in a way that is henceforth required of it, to equip it intrinsically to be, in its attitude, its ontological bearing, and its activity, the human nature of the God-man; to express in itself the manner of being coming to it from God; to be the real foundation of the relation which is the hypostatic union so far as it unites two natures that remain distinct, a relation which is real and has its real foundation (not its efficient cause!) in the human nature alone.

The union we are speaking of is a certain relation that is perceived to exist between the divine nature and the human nature, according as they are conjoined in the one person of the Son of God. But every relation between God and a creature is really in the creature, and arises from some change in the creature; in God, however, it does not exist really, but only according to our way of thinking, because it does not arise from any change in God. Therefore we must say that this union we are speaking of is in God not really, but only according to our way of thinking; but it really is in the human nature, which is a creature of a sort; and hence we must conclude that it is something created. (32) (Ibid., q.2, a.7; ad I et ad 2; a.8.)

In the case of creation, the relation produced by the change is real only in the creature, and its foundation is the whole entity of that creature as brought into existence by God. The situation in the Incarnation is analogous. The relation brought about by the union is real only in the assumed human nature, and its foundation is the manner of existing and subsisting conferred on this human nature, causing it to be wholly referred to God; and this reference can be expressed in the human nature only in accord with its capacity. We should note that, as the relation imparted by creation is not an accident, so the relation imparted by the Incarnation is not, in the first instance, an accident: it is the conferring of subsistence and, in this sense, of existence. But, as we should like to point out, such a subsistential relation demands an accidental change of a highly special order in the human nature, and this change is the adaptation of the nature to such subsistence.

Therefore this foundation of the relation, this conformation, this adaptation, this expression, this effect produced, this received perfection corresponding to the active union, must involve a relation and proportion to the Word. The formula is audacious, no doubt. But how can we make any compromise? It is the sole reason for the relation's existence, and the cause producing it can have no lesser effect. The nature that receives the effect must be adapted to it.

When God Himself lays hold of the creature that comes entirely from Him, He knows how to clasp it. The power at work is that which effected creation. But what is here accomplished is greater than creation. In raising up a being from nothing, creation raises that being to the level of a creature; the Incarnation raises a being above that being's level up to the heights of the infinite. If the change – and we understand the sense in which the word is used – that occurs in creation is complete, the unique kind of change which the Incarnation involves is infinitely more complete. But the nature that is affected is no less open to such a change. Indeed, it is more so; for could nothing be said to be open to a change throughout its whole being?

That this human nature may fittingly be what the assuming of it causes it to be, it must be divine, so far as it can; otherwise it would be a sort of negation of the union. This is the reasoning of St. Thomas. "Christ is true God in His person and His divine nature. However, since the distinction between the two natures remains notwithstanding the unity of the person, the soul of Christ is not divine by its essence. Therefore it must become divine by participation, that is, according to grace." (33) (Ibid., q.7, a.I ad I.)

"It must become divine by participation." Since the human nature is not divine in itself, it must become divine in some other way, through the union, by the participation it receives. We see how far the reasoning goes; or rather, we do not see, for the perspectives vanish in infinity. Since this man who is Christ is God, He must be God in His very humanity, so far as this is possible for a human nature.

"It must become divine." The human nature, in all the perfection it can have, is human. To be God's nature, it has to become divine. Being human, it cannot be divine except by being divinely human. But what can that mean? In any case, however great the amelioration may be, it cannot be an alteration, even a slight one; and, in this sense, it cannot be a change.

Natures are like numbers or definitions: the slightest addition or subtraction makes them cease to be what they were. If you add one to ten, you have not got a more perfect ten; you have something else than ten. If the change called forth by the Incarnation were to modify the assumed matter in this way, if it were to add some properties lying outside the area of the extension, even though only virtual or possible, proper to the nature, it would make the nature cease to be human, and so there would be no Incarnation.

The documents of the faith are meticulous on this point. The human nature of Christ is a human nature, and nothing else than a human nature. It is exalted, glorified, bettered; assuredly. But is it only half human? Absolutely not. To speak more precisely, we can in no way question the consubstantiality of this nature with our own, and we may not imagine that it fuses more or less with the divine nature. (34) (Symbolum Epiphanii (Denz., 13); St. Leo I, Tamus ad Flavianum, 4 (Denz., 144); Council of Chalcedon (Denz., 148).) In the first case, Christ's perfect union with men would be brought to nothing; in the second, the true God-man would cease; in either case, Christianity would collapse.

Such a perfection should not be conceived primarily as an accretion of new qualities. The greater these would be, the more would Christ's resemblance to other human natures be obscured. In the case of the Incarnation, those qualities would have to be such that the resemblance would tend toward God. As the preceding pages have indicated, this perfection must be a transcendent actuation brought about by union with the pure Act; it can be nothing else than a pure adaptation; a pure assimilation and participation of one of the two natures with reference to the other. But only the human nature can be thus adapted.

Hence it must have both an absolute character and a relative character: absolute, because it is an intrinsic manner of being, which is a true foundation for a true union and truly establishes a state of union; relative, because it is there as an effect ever being actually produced by the union and as the expression in the assumed nature of subsistence in the other nature. Relative and absolute: it is the foundation of the relation, so far as the relation is real in one of the two natures; but it results from the relation, so far as the relation is the active assumption which is brought about by God, and which we conceive as a relation. Relative and absolute: it is the real and ontological reaction of one nature to the total and all-powerful communication of the other nature. Accordingly it exists only in the union.

We cannot conceive the union as a complete entity having the reason for its existence and its explanation in itself or in the human substance it affects. In the man who is Christ we cannot stop with seeing only man; this would be absurd and contradictory.

The union of the two natures is unique and unparalleled; so is the perfection itself. The union is not comprised within the categories of natural reason; neither is the perfection. As the union is a union, so the perfection is an "entity of union," and we cannot say anything more adequate or basic about it; it is an entity that has neither meaning nor possibility except in expressing in one nature the union with the other nature and in formally causing the first nature to be a united nature. Either we think of it in thinking of the union, in believing in the Incarnation, and in envisaging the two natures, or else what we have in mind is not it at all.

We must familiarize ourselves with this new type of being. It is the type of being that is properly Christian and that is here realized in all its fullness, because it is here the first and total principle of Christianity. But it recurs throughout the whole of Christianity, because this sacred humanity we are speaking of is everything in all of us. We shall come back to it repeatedly; and so we have to show how it is rooted in Christ's divinity and humanity. Here we have its first appearance, its first assertion of itself. Ontologically, it is the human formula of the Incarnation; it is that which, on the human side, corresponds to the hypostatic union.

We must see how exact the correspondence is; how, as expression and effect of the union, it essentially supposes that the natures are closely and ontologically united and that, nevertheless, they are strictly distinct, thus avoiding both the heresy of Nestorius and that of Eutyches. The human nature, though completely dependent on the union, remains human; and this denies Monophysitism. But, while remaining human, it exists in a way which expresses the union and which is the reason why it exists and can exist only in the union; and this excludes Nestorianism.

To get an idea of this special type of being, of this "entity of union," we may think of what takes place in the human body when the spiritual soul animates it. The body is made up of bones and flesh, and yet it is quite capable of expressing thought and decision, or even virtue and holiness. The eyes are but blood and liquid, yet they sparkle with intelligence. The curving lips are but skin and muscle, and yet they reveal the thoughts of the intellect. But if the soul withdraws, the absence of all this is most impressive. Nothing remains but an inert mass over which for an instant, like a smile that vanishes, there flits a hint of expression and character. And that used to be the body: the body that manifested itself and acted in a certain way; but all this was perpetually being produced in the body by the soul, as being the work, the sign, the translation of the soul. In its substance the body was material, but nevertheless was spiritualized, because, united to the spirit, it had a sort of "being of union" with the spirit.

Of course the comparison, like all comparisons, is deficient, but it has roots in tradition. (35) (Cf. The Creed of St. Athanasius (Denz., 4), and St. Thomas, Summa, IIIa, q.2, a.2 ad 2.) There are others. We may think of a pinch of iron filings attracted by a powerful magnet and becoming magnetized in turn. Provided we do not dwell too much on the physics of the case, we may say that the filings now possess a quality that is in them only through their actual union with the master magnet: an entity of union, so to say. Other comparisons will be invoked in due course.


The motive that underlies this perfecting determines its nature. The union with God realized in the Incarnation, the perfecting of the human nature that makes it divinely human, essentially depends on what God is and what the Incarnation is.

God is Being itself. He is "He who is," purus actus essendi, ipsum esse subsistens, as theology and metaphysics agree in defining Him. Through the Incarnation He unites Himself to a finite being.

A finite being, on the other hand, as envisaged by metaphysics, is something that shares in being. In terms of being, that is, according to what it essentially possesses in all that it is, it is defined by an affirmation of being within a negation of being: it is something that shares in being; it is what it is and is not anything else. But in any case it is something that shares in being; what else could it be?

Through the union which is the Incarnation this finite being is truly God. To give a scientific explanation of the union we could, no doubt, have recourse to various theological systems, but they all have to come to this central point: the man who is Jesus Christ is strictly God. This simple rendering of the mystery in terms of the philosophy that is traditional in theology throws some light on the question.

God is Being itself; the human nature is something that shares in being, and absolutely nothing else. A priori, therefore, no opposition between the two is perceived that could prevent the first from uniting itself to the second, by taking it up into unity of being.

I profess the truth which is evident to spiritual souls that no nature can be contrary to God. If God is, and if this can be properly asserted of God alone (for what truly is, remains so unchangeably, since what changes was something that exists no longer, and will be something that it is not as yet), God has no contrary. If you ask us what is the opposite of white, we reply black; if you ask what is the opposite of hot, we reply cold; if you ask what is the opposite of fast, we reply slow; and so of other instances. But if you ask what is the contrary of that which is, we rightly answer that nothing is. (36) (St. Augustine, De fide et symbolo, 7 (PL, XL, 185))

God's absolute transcendence, which is the reason why He simply cannot have anything univocally in common with the finite, makes Him the first principle and necessary exemplar of all that is finite. Any being or aspect of being that would be completely lacking in analogy with Him who is Being itself, would be nothing. Everything that exists, in every particle of its being, exists only by having being from Him. Such a being is pure plasticity, capacity, complete receptivity with regard to influences emanating from that Being who causes being; for its existence is wholly owing to influences received from that Being.

Undoubtedly we can imagine some of God's actions which, when we think of His absolute power, would be in conflict with the very being of the finite; as for example, if God were to will that a man should be a tree. But in this case the opposition would come, not from God as God, but from the object to which the command is directed. But when there is question only of Being, and when God's will is simply that a being which in itself is finite should be Being itself, we do not see from what source a difficulty could arise. What could obstruct the action of the first on the second when the second is defined, caused, and constituted by the reception of that action?

Assuredly this does not explain in a positive way how a man can be God; for that we should have to have a positive and adequate idea of God, of Being itself. Nor do we deny that the positive possibility of the Incarnation is a mystery. But we believe we can perceive with certitude that the impossibility of the Incarnation cannot be shown.

The situation would be quite different if the hypostatic union were to join a finite nature to another finite nature, for example, a human nature to an angelic nature. At first sight, such a union would appear to be less astonishing; in reality, we think, it is unthinkable. For an angel exists in a definite way that excludes all other ways of existing, including the human way. The same is true of a man. In order to become an angel, a man would have to become what is a negation of himself, and so would cease to be himself: which is an evident contradiction and impossibility.

What is true of an essence is true of personality. However we may define personality, it is, in each essence, correlative to that essence. The illimitation, the totality, the absolute finality which personality connotes and which could exist without restriction if it were to exist separately in itself, actually exists only through the real existence of the individual in which it is realized, and hence with the limitations and exclusiveness involved in such existence. Therefore an angelic personality would be destructive of a human nature, and vice versa. Moreover, the unity of the person would require a real union of the natures and an adaptation of one of the two or of each of them to the other: that is, a union with what negates it and an adaptation to what excludes it; and this is resignation to death.

But to become God, to be God, is simpler; or rather, since the question at issue is the impossibility of showing the impossibility of such a supposition, it cannot but be simpler. God does not exist in a way different from the way man exists, for He does not exist either in one way or in another: He simply is. Or, if we insist on talking about a way of being, His way is to be without restriction or negation, to be entirely and eminently nothing but Being; to become God cannot in any way involve ceasing to be oneself.

Since all the positive ideas we form of God are unavoidably inexact and finite, they are opposed to other ideas. They admit of such opposition because of their limitations; their defect consists precisely in the fact that they have limits.

If anything were by nature opposed to God's fullness of being, it would be radically opposed to itself, to the very principle of its being. The rebellion of any being against God is truly insurrection against itself and its natural law. For the essential law and, we may say, the very substance of every being is to be in conformity with Being itself.

For the humanity of Christ, therefore, the assumption cannot but be in full accord with what is more essential to its being than it is itself, and must cause it to exist in God's Being in the most perfect way that is possible for it.

The simplicity of this union indicates how simple its effect will be. Union with Being itself affects being as being. A being is subject to other influences externally and passively. But this influence, which comes from Being itself, it receives by merely being. This influence, coming as it does from the first and eternal cause of its being, enters into it at the very inception of its own being. Since the subsistent Being is more interior to every being than any being is in itself, the influence can be more interior, more "natural" to such a being, than its own being. If that influence comes from the innermost life of the supreme Being, it will express itself all the more deeply in the innermost being of that which receives it. In the Incarnation, therefore, where the influence is total, it affects totally the being of the assumed humanity. The Man who has this humanity will be God. He will have no other ultimate being or personality than a divine personality; and the latter, although strictly belonging to God, will be no less easily and "naturally" the Man's personality. Thus affecting the very being of the human nature, this action of the supreme Being necessarily confers being; it gives being such as befits one who is very Being.

We have only to consider the assumed nature to perceive what the union produces in it. We call it being, not to suggest that it is something outside the union or that it has its own proper being, but because it is not nothing. This usage of the term is delicate; we require it for giving expression to our reasoning; we hope that the reader will allow the context to be its commentary. Hence we say that the union of a finite being with the absolute Being in personal unity can have no other immediate effect than to cause it to be in as absolute a way as possible.

To be, for a human nature, means to be human; and to be as absolutely as possible, can mean nothing else than to be human as absolutely as possible. Nothing else will do. The nature cannot receive some new, unheard-of quality; it is humanity, and can be nothing else than humanity. But it is such utterly and infinitely; does not theology point out that the grace which, in this humanity, is the elevation due to the union, is as infinite as it can be? In the same way existence lays hold of essence, not by causing it to be something else, but by causing it to be; not by adding to it an accidental perfection of any kind, but by giving to it as real what it had as possible.

With all the greater reason this is true of absolute existence when it assumes a human nature, to the point of becoming its most basic and incommunicable existence, as theology puts it, and to the point where we can truly say that the Man it constitutes is strictly God, as the whole of Christian dogma teaches. That existence causes the human nature, not to be something else, but simply to be, and to be in union and proportion with Being itself; not to receive some accidental perfection, but to have in a way that is worthy of God all that it would have in its own way if it were left to itself. The pure Act, communicated to the human nature, affects the nature in the manner of an act, in the manner, we may say, of its own act, but infinitely more perfectly, because it is Act in an infinitely more perfect way; it makes the human nature exactly what a human nature is, but with an intensity of existence that reflects and expresses Being itself, through a transcendent human actuation.

The human nature receives the Creator's action twice and in two ways. It receives that action, first, by a finite title and simply, in order to be a simple human nature. But it also receives the action on the score that it is assumed, in order to be a human nature, indeed, but a human nature that is one with the Creator. And it receives the Creator's action twice in its capacity as human nature, and hence in order to be a human nature; but the second time it receives the action in such a way as to be the human nature of God and therefore, to some degree, in the way of God, with an intensity and perfection that are, so to speak, divine.

God is not opposed to anything; therefore, in taking over all that is in human nature, He does not exclude or impair anything. The Infinite is everything, and is also everything with respect to the finite. God's action can be penetrating and incisive to the last degree, and has to be. But the nature thus permeated through and through remains intact and virginal, and clings all the more firmly to its being, just as a crystal ball penetrated by the sun remains transparent, but with a transparency that has become brilliant.

Tradition refers to all this as divinization, grace, fullness of grace; yet it is an accident inhering in the human nature, and hence is human. This is the point of view from which we must consider it here. The perfection is human, and therefore implies a human way of existing that is supernaturally perfect or even divinely perfect, since divinization is in question. But in the humanity there is nothing but humanity. That is the dogma taught at Chalcedon, and it must dominate all Christology; we are encouraged to see that our considerations come back to the dogma that was their point of departure. Christ is perfectly man, perfectly God, perfectly one; one and the same Son, our Lord Jesus Christ, is perfect in divinity and perfect in humanity. (37) (Denz., 148.)

The human nature of Christ is an integral and perfect nature of a true Man who is complete in what pertains to Him and complete in what pertains to us. (38) (St. Leo I, Tomus ad Flavianum, 3 (Denz., 143)) His human nature does not differ from ours except in the intensity of its existence, and that but makes it the more human. This difference, consequently, is not at all a difference; it does not make Christ less consubstantial with us; it makes Him more consubstantial, perfectly consubstantial with us. Similarly the perfection produced by the union is undoubtedly a change, as compared with what the humanity would have been without it. At the same time it is not a change: it is the ultimate and absolute identification of the humanity with itself, which "is" infinitely more than it would be otherwise, and therefore "is" itself supernaturally.

Since this supreme perfection "is" supremely, and since it is supremely human, it can exist only in the manner of the human nature. But human nature has two essential aspects that are inseparable from each other: an individual aspect and a social aspect. Hence the supreme perfection here in question must have the same two aspects: individual and social. Scholastic theology holds that the grace of Christ, which is precisely this perfection as defined in function of the divinity and of assimilation to the divinity, is simultaneously individual grace and the grace of headship, that is, grace destined to influence all men; we may perhaps call it social grace.

The individual perfecting is not the object of this book. Yet we may say a few words about it, as it is correlative to the other and is necessary for a clear understanding of the other.

As the human nature of God, Christ's human nature is the splendor of humanity and the glory of our race. His unique personality, which is that of the Word, does not prevent Him in any way from having all the individual traits that in other men are so deeply rooted and so expressive of human personality. But everything in His human nature subsists in the Word in whom it has its ultimate complement, and is personal with the Word's personality.

The human nature of Christ is not sui iuris in the ordinary sense; that is, it does not possess the primary principle and the ultimate term of its acts in a personality of its own order. Yet it is not without dominion over all these acts; indeed, it exercises a more complete dominion over them, because it governs them by the power of the Word, who belongs to it. Being thus iuris Verbi, it is all the more sui iuris, but iure divino.

To appreciate the interior autonomy and the splendid detachment of conscience characteristic of Christ's human nature, we have to observe it in action, during the days of His mortal life, in its sovereign freedom, its simple spontaneity, and its perfect surrender. It does not have to be continually solicitous about playing a role, and is not wholly absorbed in an effort to preserve a listening docility, in fear of introducing a human element into divine conduct. God has come among us precisely to take over what is human. In His human nature He goes, comes, speaks, gives expression to human thoughts and feelings; He has human preferences and displays them, human indignations and utters them, human joys and fears which He allows to be perceived. God's human nature has a natural, human mode of activity.

It does not retire to the background; it has an unparalleled emphasis of affirmation and of self-assertion. We know the assurance with which this self is exhibited in St. John: "But I tell you; amen, amen, I say to you; I am the light; I am in the Father and you are in Me; everything is for man and for eternal life." This audacity is not less prominent in the Synoptics: "Moses spoke in the name of God; but I say to you." All morality, all the most absolute demands are founded on this self, without further justification; all aspirations and all finality, even the most exalted, lead to this self, without any necessity of further recourse.

At the same time Christ's human nature asserts its relation of complete dependence on the Father: God alone counts, God alone is good, God alone accomplishes everything. But it asserts this supreme excellence of God without ceasing to assert itself; the double assertion, expressive of the very mystery of the Incarnation, is for it a simple and obvious thing on which it does not have to reflect, for that assertion indicates its manner of being; to comprehend and proclaim it, Christ's human nature has only to exist and to live.

We may remark in passing that this is the way Christ's human nature understands the Incarnation; and hence this is the way its members will understand the Incarnation. Sharing in Christ's humanity and living their lives as earnestly as possible in their capacity as members, they will understand in virtue of what they are, by sharing in Christ's human understanding, at present by faith, later by vision. And this brings us to the social aspect found in Christ's humanity.

The social perfection of the assumed human nature is the main point of interest, as far as this book is concerned. This is what makes Christ, as man, head of a mystical body. Every man, as we said in an earlier chapter, (39) (Cf. chap. 5, sect. 3) is social by nature: in a certain sense, man is universally human. Indeed, he is doubly social: first, he is a man by being consciously and internally what all other men are; secondly and chiefly – although this can hardly be expressed in human words – because the human form possesses its own act, really though imperfectly, and therefore, really though imperfectly, possesses its own illimitation.

This sociability, as we also said above, implies, besides an interior union with other men, an interior union with the whole human universe. This universe is needed in order that man may attain complete life and in order that the human form may manifest all its essential powers and relations. We do not intend to speak of this latter aspect at present, but we should not lose sight of it. The other aspect, union with men in general, is by far the more important factor in sociability.

This sociability exists in the human nature assumed by Christ, because it is a human nature. On this score God's donation which is realized in it and which, we may say, it is, is of concern to all men, by reason of the natural union it has with all. In the human race, therefore, the sacred humanity is a principle of divinized life, a unity and a head with regard to the supernatural order.

But much more has to be said. Christ's human nature has this sociability, as it also has humanity, in an eminent way that befits a human nature belonging to God. The perfection that raises it above all men, also places it in all men. In assuming and divinizing a human nature, God assumes and divinizes all humanity, as the Fathers say so often. Therefore He assumes and divinizes its sociability. He assumes and divinizes human nature socially: the Word has come to dwell in all of us through one of us.

This supreme sociability is a property of Christ as mystical head. It involves a union of a Man with all other men, a possession of all human reality, and a splendid way of being Man, as is fitting for a Man who is God.

The fullness of humanity embraces all the varieties of psychology, character, and mentality, incompatible with one another but all deeply human in their limitless number, that are realized in different individuals. To be perfectly a man, one must possess them all; not by formally realizing them in one's concrete humanity, which is impossible, but in the only way that is free from contradiction, by being fully united to those who possess them. Such is the union, divinely perfect in a sense, that the humanity of God must possess.

Ens et unum convertuntur. In his relations with other men and with the universe, man has an indefinite number of human perfections which are truly his, although they are outside of him. In order that he may fully exist and may be fully one, he ought to possess them within himself, and therefore he ought to be united to all mankind and to the whole universe as perfectly as possible, since that is the only means he has of possessing them. Accordingly the human nature assumed by Christ, perfectly realizing its unity within itself, will realize within itself all mankind and the universe.

St. Thomas remarks that what a being possesses, it possesses more perfectly in proportion as it is able to communicate its possessions. (40) ("Among things that are filled with any goodness or perfection, the one from which goodness or perfection flows out upon other things is found to be filled to greater repletion; for example, what can shed light on other objects, shines more brilliantly than they. Therefore, since the man Christ possessed supreme fullness of grace, as being the only-begotten of the Father, grace overflowed from Him to others, so that the Son of God, made man, might make men gods and sons of God, according to the Apostle's words in Galatians 4:4 f.: 'God sent His Son, made of a woman, made under the law: that He might redeem them who were under the law: that we might receive the adoption of sons.' " St. Thomas, Compendium of Theology, pp. 240 ff., Part I, chap. 214; cf. Summa, IIIa, q.8, a.5.) When a social being such as man is in question, the principle is even truer. Man does not truly possess what belongs to him on the social level and by a social title, unless he is able to give what he has. Man does not attain his full human formation unless he also forms other men. Hence, to possess fully the supernatural perfection proper to a man, Christ's human nature must possess a perfection that is sufficient for all mankind, in a sort of universality and transcendent sociability.

As we have remarked, the form in every man has its illimitation in the same measure as it has its act. What, then, will the form be in this Man, who is illimitation and infinity itself? In the order of form the illimitation of His form will be more absolute, so far as is possible in a single individual.

In other human individuals, the reception of form in matter is the ultimate reason of individual subsistence, and the limitation it induces is also ultimate and hence definitive. In the humanity of Christ this reception also takes place and is real, and the individual character is marked; indeed, we have pointed out that this is much more the case. But such reception in this human nature is not ultimate, and the same is true of the limitations it induces. The subsistence of God is the sole ultimate, for it is the basis of everything in Christ. But God is pure infinity and unity, whereas matter is finitude and internal division. Accordingly the "ultimateness" coming from God will be altogether different from the "ultimateness" coming from matter. Individuation will be there, certainly, for individuation is essential to human nature. But this individuation will be through penetration into the infinite, and hence by "infinization," rather than an individuation through separation from others and by limitation.

But this "infinization" is on the human level, through the realization, in this human nature, of the Infinite and of all that can be infinite in humanity, so far as an individual human nature is capable of such exaltation. We have noted the doctrine of St. Thomas that grace, the supernatural perfection of this human nature, is infinite so far as it can be; it is infinite in its own line. If we reflect that grace is an accident by which the human nature is made holy and divinized, we shall see what infinity in the assumed humanity is presupposed by the infinity of the grace received. Is not God infinite, and can anyone be divinized without being raised to the order of infinity?

We may add that Christ’s soul does not receive the final seal of its union with matter and its restruction to a definite individuality, making it exclusively what it is and giving it its ultimately incommunicable existence, (41) (Ut per se et separatim existat.) except in its union with the Infinite and its subsistence in the unlimited Act. Consequently it is individual and even, in a sense, transcendent; but it is such with a transcendent illimitation: an illimitation that is proper to the human soul, but pushed to the extreme limits of its possibilities.



Emile Mersch: The Teaching of Philosophy on Man and his Unity

Emile Mersch: The Human Consciousness of Christ and the Consciousness of Christians

Emile Mersch: Theological Theory