"The good of the grace of one soul is greater than the good of the nature of the whole universe"
- St Thomas Aquinas Ia IIa, q.24, a. 3, ad 2

— A Commentary on the Third Part of St Thomas' Theological Summa

by Reginald Garrigou-Lagrange, O. P.



St. Thomas has the following considerations about this mode of union.

1) The union itself (q. 2).

2) The person assuming the human nature (q. 3).

3) The nature assumed and the perfections or defects of this assumed nature (q. 4-15).

Then the consequences of this union will be discussed, namely, as regards being, volition, and operation.

Hence this second question is about the essence of the Incarnation, or about the hypostatic union.

This second question contains twelve articles, and is divided into three parts.

The first part (a. 1-6) discusses what is and what is not the nature of this union. It inquires 1. whether the union took place in the nature; 2. or in the person; 3. or in the suppositum; 4. whether the person of Christ is composite; 5. what is the union of body and soul in Christ?

Thus the question is gradually solved, and the sixth article, which is of great importance, unites the preceding articles, by asking whether the human nature was united to the Word accidentally.

The second part considers the union with reference to the divine actions, which are creation and assumption (a. 7, 8).

The third part considers the union with reference to grace: Is it the greatest of unions (a. g)? Did it come about by grace (a. 10)? Was it the result of merit? Was the grace of union natural to the man Christ (a. 12)?

This second question virtually contains the whole treatise on the Incarnation, just as the third question of the first part of the Summa in which God is defined as the self-subsisting Being, virtually contains the whole treatise on the One God.

As regards the order of the questions, it must be noted that in the Summa Theologica St. Thomas follows the logical order rather than the historical, whereas in the Contra Gentes (Book IV, q. 27 f.) he follows primarily the historical order by refuting the various heresies that arose concerning the Incarnation.

Heresies concerning the Incarnation. For an understanding of the articles of this question, a brief explanation must be given of the principal heresies condemned by the Church: Arianism, Apollinarianism, Nestorianism, Monophysitism, and Eutychianism.[383]

A threefold division is made in these heresies, inasmuch as some erred concerning the divinity of Christ, others denied His humanity, and finally some erred about the union of the two natures.

God permits errors so that by opposing them the truth may be presented in clearer light.

Divinity of Christ Humanity of Christ The union of natures
This was denied by the Ebionites, Cerinthians, Arians, and others. The Arians and Apollinarians denied that Christ had a soul. The Docetae and Valentius denied that Christ had a real body.

The Nestorians denied that the union was personal.

The Eutychians and Monophysites denied that there were two natures in Christ

Thus it was that already in the first four or five centuries of Christianity almost all the errors possible against the Incarnation were proposed.

1) The divinity of Christ was denied.

In the first century, by the Ebionites and Cerinthians. In the second and third centuries by the Adoptionists and Gnostics.

In the fourth century, by the Arians. They declared that Christ is not the Son of God consubstantial with the Father but is a creature; that the Word (Logos) pre-existed, but was created, and is a mediator, who assumed in the womb of the Blessed Virgin Mary only a body and not a soul. Thus the Arians concluded that Christ is neither truly God nor truly man. Hence St. Athanasius replied[384] that such a conception of Christ made it impossible for Him to satisfy for the human race or free it from sin. This means that the denial of the mystery of the Incarnation includes the denial of the mystery of Redemption, and thus there is left but the semblance of Christianity.[385]

Later on, in the sixteenth century, the Socinians denied the divinity of Christ, and the same must be said in our times of the Unitarians, who deny the Trinity, and also liberal Protestants and Modernists of the present day.

2) The humanity of Christ. Some denied that Christ's body was real, others that He had a soul. The Docetae, such as Marcion and the Manichaeans, said that Christ merely appeared to have a body.

Appelles and Valentinus in the third century said that Christ's body was real but celestial, sidereal or aerial, and therefore He did not derive His human nature from the Virgin Mary.

The Arians and Anomoeans taught that the Word did not assume a soul. In the fourth century the Apollinarians held that Christ had only a sensitive soul, and that the Word performed the functions of the rational soul, though they admitted, contrary to the Arians, that the Word was not created.[386]

3) Some denied the unity of person in Christ, others the twofold nature. In the third century, the unity of person was denied by Paul of Samosata. In the fourth century, Diodorus of Tarsus said that the Word was only accidentally united to Christ. So also Theodore of Mopsuestia and the Nestorians, teaching a sort of personal union, rejected it really, however, inasmuch as they posited merely a moral union between the two natures. In this way they sought to refute Apollinarianism. The consequence of these errors was the view that Mary is not the Mother of God.

The prominent opponent of the Nestorians was St. Cyril of Alexandria who, in refuting them, availed himself of the principal argument used by St. Athanasius against the Arians, namely, that, if Christ is not God, but only morally united to Him, as a saint is, then how could He satisfy for us or free the human race from sin?[387]

In our times, too, the disciples of Gunther denied the unity of person in Christ, since they defined a person as a self-conscious nature, for in Christ there are two self-conscious natures.

So also, Rosmini acknowledges between the Word and the human will in Christ merely an accidental union, inasmuch as the human will, since it was completely dominated by the Word, ceased to be personal. Rosmini says: "Hence the human will ceased to be personal in Christ as man, and, since it is personal in other men, in Christ there remained but the human nature."[388] Thus the union in Christ between the Word and the human will would be merely accidental and moral. The error of Rosmini and Gunther is that both do not seek to define person ontologically by reason of subsistence, but only psychologically through self-consciousness, or by reason of liberty. This error is the result of the nineteenth-century psychologism.

The Modernists say about the same, since they reduce the hypostatic union, if they give it any thought, to God's influence upon the human conscience of the historic Christ, or to the subconscious self in Christ by which He perceived that He was loved by God above all others.

Finally, the Eutychians or Monophysites denied that there were two natures in Christ. Eutyches posed as the adversary of Nestorius and the defender of the theology of St. Cyril of Alexandria, which he did not understand. He was a man of little learning, and obstinate, and so he went to the other extreme of Nestorianism. He was so insistent in affirming the unity of person in Christ against the Nestorians that he ended in denying His twofold nature. He said: "I confess that our Lord was of two natures before the union; but after the union I acknowledge one nature,"[389] either because the human nature was absorbed by the divine nature, or because each nature commingled to form a third nature, distinct from each before the union, or because the human nature and the Word were absolutely united as the soul and the body are. Hence Eutyches by this method succeeded in proclaiming something that the Nestorians denied, since they denied that the Blessed Virgin Mary is the Mother of God.

In the fourth century, however, the Monothelites, professing that Christ had but one will, by this very fact rejected the doctrine that there were two natures in Him. The followers of the modern heresy that declares the Word really emptied Himself, also deny a twofold nature in Christ, since they hold that the Word, at least partly and for a time, set aside His divine attributes.[390]

Thus several heresies made their appearance as excessive reactions against the preceding ones; so also not infrequently it happens that the human mind in its aberrations passes from one extreme to the other.

1) Arius says that Christ is the created Word united to a human body, without a soul. St. Athanasius says correctly: then Christ could not have satisfied for us.

2) But Apollinaris says that Christ is the uncreated Word united to a human body, without a rational soul, since this latter was capable of sinning, and consequently could not satisfy for us.

3) Then Nestorius, in a reactionary spirit, says that Christ has a rational soul which is morally united to the Word. Thus the union of the natures is no longer personal.

4) Finally, Eutyches goes to the other extreme and asserts that the union of the natures is not only moral but also physical, meaning that after the union there is only one nature. This doctrine is Monophysitism.

These last three mentioned heresies deny that the Blessed Virgin Mary is the Mother of God, and they do so for various reasons. Apollinaris says that Jesus is not a man, Eutyches says that His body is not of the same nature as ours, whereas the Nestorians assert that Jesus is not God, but morally united to Him.

The dogma strikes a medium between Nestorianism and Monophysitism, transcending both of them, inasmuch as it states that both natures in Christ are united in one person.

Teaching of the Church. It is evident from the Gospels, the Apostles' Creed, and the condemnation of the above-mentioned heresies.

1) Already even in the Apostles' Creed it is stated that Jesus Christ is truly God and truly man, inasmuch as it says: "I believe... in Jesus Christ His only Son, who was conceived by the Holy Ghost, born of the Virgin Mary."[391]

2) In the First Council of Nicaea (325) and the First of Constantinople (381), the consubstantiality of the Word with the Father is explicitly declared. The First Council of Nicaea says: "God of God, light of light, true God of true God, born not made, of one substance with the Father, which the Greeks call homoousion."[392] It is likewise declared against the Docetae, Gnostics, and Apollinarians that "Christ had a complete human nature."[393]

3) In the fifth century, the Athanasian Creed declares all that is of faith on this point, in these few words: "Jesus Christ the Son of God is God and man. God, of the substance of the Father, begotten of the Father from all eternity; and man, of the substance of His Mother, born in time.... Who, although He be God and man, yet He is not two, but one Christ; one, not by conversion of the Godhead into the flesh, but by the assumption of the manhood into God; one altogether, not by confusion of substance, but by unity of person."[394]

The Council of Ephesus (431) proclaims against Nestorius that there is one person in Christ, and two natures hypostatically united,[395] and also proclaims "that this same Christ is both God and man."[396]

Likewise, not long afterward (451), the Council of Chalcedon defines against Eutyches and the Monophysites that "One and the same Christ, Son, Lord, Only-begotten, must be acknowledged to be in two natures, without confusion, change, division, separation; the distinction of natures being by no means destroyed by their union; but rather the distinction of each nature being preserved and concurring in one person and one hypostasis;[397] not in something that is parted or divided into two persons, but in one and the same and only-begotten Son of God the Word, the Lord Jesus Christ."[398] This text is quoted almost verbatim in various subsequent councils, the Council of Florence being the last to refer to it (1441).

Finally Pope Pius X condemned the following proposition of the Modernists: "The Christological teaching of SS. Paul and John, and of the Councils of Nicaea, Ephesus, and Chalcedon is not Christ's own teaching, but that which the Christian conscience conceived concerning Jesus."[399]

Let us now undertake the philosophical analysis of these definitions of the Church.

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"God gives us some things, as the beginning of faith, even when we do not pray. Other things, such as perseverance, he has only provided for those who pray."

St Augustine

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"God has no need of men."

St Philip Neri

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"Many words do not satisfy the soul; but a good life eases the mind and a clean conscience inspires great trust in God."

Thomas á Kempis

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