Thomas Aquinas on the Obedience of the Son (re: “The Obedience of the Eternal Son,” Part 3)



After questioning the motivation for the essay “The Obedience of the Eternal Son” in my first post, and then justifying my representation of the essay in the second, we are now in a position to enter into the substance of the discussion. But rather than continue with polemics, I have decided to take a piece of advice from Dr. Michael Allen and engage more constructively. (Plus, very few of my readers are even familiar with the essay under consideration as it is not easily linkable.) I do intend to continue questioning the thesis of the so-called “obedience of the eternal Son,” but rather by presenting what I believe to be an accurate representation of the Biblical data, and then comparing several alternate claims, concluding with an assessment of Drs. Swain and Allen’s parrying of the objections of Thomas Joseph White to their thesis.

As the work of Thomas Aquinas is the primary resource for Swain and Allen’s coordination of “the obedience of the eternal Son” with “traditional trinitarian metaphysics in the classical Catholic and Reformed tradition,” I will accordingly present what I perceive to be the Catholic and Reformed tradition as found in Aquinas’s Summa Theologiae.

[I realize that there are a significant number of quotations below, which can make for rough reading. I apologize. But as a layman, I am aware that my own summaries without ample textual support are unlikely to convince the skeptical reader.]

Relative Distinction by Procession

In the divine persons there is nothing for us to consider but the essence which they have in common and the relations in which they are distinct. (I, q. 42, a. 1, ad 4)

Assuming the Nicene faith, that the Father, Son, and Holy Spirit are homoousia—that is, one in substance, nature, and essence—and three in person, hypostasis, and subsistence, then the above Thomistic conclusion appears to be absolutely necessary. If God is one essence, and each person is perfect and complete God, then there can be no distinction in property, attributes, or perfection between the three persons. All that is God must be true of each person, for God is supremely simple. There cannot be part of God in the Father, part in the Son, and part in the Spirit, or we would have either an extended, material, limited and imperfect God in parts, or we would have three gods, each distinguished by his own set of properties. Thus, there can be no distinguishing absolute properties that oppose Father to Son or Father and Son to Spirit.

“So,” writes Aquinas, “as the three persons agree in the unity of essence, we must seek to know the principle of distinction whereby they are several” (I, q. 40, a. 2). His answer is that there is relative opposition and distinction due to the eternal processions of the Son from the Father, and the Holy Spirit from the Father and the Son. It is the relation of origin that distinguishes the persons. And these relations are not absolute properties, but only relative, for “relation in its own proper meaning signifies only what refers to another” and not a distinction of attributes between the relatives (I, q. 28, a. 1). These are indeed real relations and not simply logical, but they are not relations that imply distinction of nature between the persons. Aquinas explains this difference:

Such regard to another exists sometimes in the nature of things, as in those things which by their own very nature are ordered to each other, and have a mutual inclination; and such relations are necessarily real relations; as in a heavy body is found an inclination and order to the centre; and hence there exists in the heavy body a certain respect in regard to the centre and the same applies to other things. Sometimes, however, this regard to another, signified by relation, is to be found only in the apprehension of reason comparing one thing to another, and this is a logical relation only; as, for instance, when reason compares man to animal as the species to the genus. But when something proceeds from a principle of the same nature, then both the one proceeding and the source of procession, agree in the same order; and then they have real relations to each other. (I, q. 28, a. 1)

But we must further note,

Relationship is not predicated of God according to its proper and formal meaning, that is to say, in so far as its proper meaning denotes comparison to that in which relation is inherent, but only as denoting regard to another. (I, q. 28, a. 1, ad 1)

The relations of origin that distinguish the persons of the Godhead are not substantial relations—relations resulting from differing natural distinctions; such is inconceivable in the one simple God. They are merely relations of “regard to another.” Anything else would again divide the persons or contradict the nature of divinity as revealed in the Scripture. Therefore, what distinguishes the persons are relations only, and these relations are relations of origin, viz., Peternity, Filiation, and Spiration.

The Father and the Son are in everything one, wherever there is no distinction between them of opposite relation. (I, q. 36, a. 4)

“Relation alone multiplies the Trinity of the divine persons.” (I, q. 40, a. 2)

The Father is denominated only from paternity; and the Son only from filiation. (I, q. 28, a. 1)


It also must be noted that these relations of origin are not accidents of the divine nature, but are essential; that is, Peternity, Filiation, and Spiration are identical with the one divine essence.

[D]istinction in God is only by relation of origin, as stated above (Q. 28, AA. 2, 3), while relation in God is not as an accident in a subject, but is the divine essence itself; and so it is subsistent, for the divine essence subsists. Therefore, as the Godhead is God so the divine paternity is God the Father, Who is a divine person. Therefore a divine person signifies a relation as subsisting. (I, q. 29, a. 4)


So, when Aquinas comes to the question of equality in the Godhead, the answers are pretty straight forward. If “[i]n the divine persons there is nothing for us to consider but the essence which they have in common and the relations in which they are distinct,” and the relations themselves represent no distinction of properties or attributes save “relative to another,” then there can be no inequality among the persons of the Godhead.

[E]quality and likeness in God have reference to the essence; nor can there be inequality or dissimilitude arising from the distinction of the relations. Wherefore Augustine says (Contra Maxim. iii, 13), “The question of origin is, Who is from whom? but the question of equality is, Of what kind, or how great, is he?” (I, q. 42, a. 4, ad 2)

That is, the essence of the three persons is one and indivisible. The question of relation due to origination is simply “from whom?” and does not speak to equality or inequality. Rather, the question of equality is a matter of what kind of thing we are considering; viz., what is its essence? And for the Father, Son, and Holy Spirit, the essence is indivisible unity.

For Aquinas (and Aristotle), in order to have inequality, there must be a greater and less being compared, but there can be no greater and less in God.

[W]e cannot admit anything greater or less in the divine persons; for as Boethius says (De Trin. i): “They must needs admit a difference [namely, of Godhead] who speak of either increase or decrease, as the Arians do, who sunder the Trinity by distinguishing degrees as of numbers, thus involving a plurality.” …[I]f there were any inequality in the divine persons, they would not have the same essence; and thus the three persons would not be one God; which is impossible. We must therefore admit equality among the divine persons. (I, q. 42, a. 1)

The Father and the Son are equal in greatness, for they share in the same essence and nature:

Wherefore, just as the Son has the greatness of the Father, and is therefore equal to the Father, so the Father has the greatness of the Son, and is therefore equal to the Son. (I, q. 42, a. 1, ad 3)

Even in their relative oppositions, they share the identical dignity and power of the one nature:

For the Father and the Son have the same essence and dignity, which exist in the Father by the relation of giver, and in the Son by relation of receiver. (I, q. 42, a. 4, ad 2)

As the same essence is paternity in the Father, and filiation in the Son: so by the same power the Father begets, and the Son is begotten. (I, q. 42, a. 6, ad 3)

The Son shares the same greatness, dignity, and power of the one divine nature as filiation; the Father shares the same greatness, dignity, and power of the one divine nature as paternity. The greatness, dignity, and power of the Godhead is one and is of the very one nature and essence of God, shared equally by the Father, Son, and Holy Spirit.

Divine Missions

But what about John 14:28, “The Father is greater than I”? Aquinas answers this in the same manner as the orthodox who have gone before, viz., the Double Account: “These words are to be understood of Christ’s human nature, wherein He is less than the Father, and subject to Him; but in His divine nature He is equal to the Father” (I, q. 42, a. 4, ad 1). So, if all there is to consider in the Godhead is the one divine nature and the relations of origin, where does this lesser human nature fit in? This brings us to the divine missions; that is, the “sending” of the Son by the Father, and the sending of the Holy Spirit by the Father and the Son.

The nature of any sending has two parts, “the procession of origin from the sender” and “a new way of existing in another” (I, q. 43, a. 1). There is a “from” and “to” in every sending. But the most important thing to understand about the divine missions is that they are simply extensions of the eternal processions. Aquinas describes three ways of viewing one procession:

A certain difference is to be observed in all the words that express the origin of the divine persons. For some express only relation to the principle, as “procession” and “going forth.” Others express the term of procession together with the relation to the principle. Of these some express the eternal term, as “generation” and “spiration”; for generation is the procession of the divine person into the divine nature, and passive spiration is the procession of the subsisting love. Others express the temporal term with the relation to the principle, as “mission” and “giving.” For a thing is sent that it may be in something else, and is given that it may be possessed. (I, q. 43, a. 2)

So, the same procession can be considered in terms of its eternal relation to the sender (e.g., procession), its relation to the one sent (e.g., generation), and its temporal term and effect (mission). Thus, mission is distinguished from procession by the addition of the temporal term and effect:

Mission signifies not only procession from the principle, but also determines the temporal term of the procession. Hence mission is only temporal. Or we may say that it includes the eternal procession, with the addition of a temporal effect. For the relation of a divine person to His principle must be eternal. Hence the procession may be called a twin procession, eternal and temporal, not that there is a double relation to the principle, but a double term, temporal and eternal. (I, q. 43, a. 2, ad 3)

Missions are the extension of the eternal processions into temporality.

Aquinas distinguishes two types of missions and sendings of the Son and Spirit, the invisible and the visible. The invisible mission of each is just the sending of the Son and Spirit as sanctifying grace and presence in the heart and mind of the believer. This does not mean that there is any alteration in the one sent by this temporal extension, but only an alteration of the receiver. As Augustine says, “The Son is sent, whenever He is known and perceived by anyone” (De Trin. iv, 20). But more important to our purposes are the visible missions, and we will focus in particular on the visible mission of the Son.

Simply put, the visible mission of the Son is His coming in the flesh, uniting in one person His divine nature to created human nature. So, when the Son is said to be sent visibly into the world, we are to understand the incarnation. “But when the fullness of the time had come, God sent forth His Son, born of a woman” (Gal. 4:6). The Son was always in the world, filling heaven and earth as God, but His sending was a coming into a new mode of temporality. Aquinas writes that “the Son is said to be sent by the Father into the world, inasmuch as He began to exist visibly in the world by taking our nature; whereas ‘He was’ previously ‘in the world’ (John 1:1)” (I, q. 43, a. 1). As seen from the Son’s eternal relation to the Father (origin), His mission is simply the eternal procession itself; but as seen from the temporal effect of His mission, the procession is His coming in the flesh. It is very important to distinguish these two aspects of the one mission, i.e., the eternal procession from the sender, and the temporal coming in the flesh. For according to the former, the Son is equal to the Father who sent Him, but according the latter, He is less than the Father who sent Him. As Aquinas frames this distinction, “the notion of mission includes two things: the habitude of the one sent to the sender; and that of the one sent to the end whereto he is sent” (I, q. 43, a. 1).

Aquinas makes clear that the Son is in no wise subject to the Father according to “the habitude of the one sent to the sender”:

Mission implies inferiority in the one sent, when it means procession from the sender as principle, by command or counsel; forasmuch as the one commanding is the greater, and the counsellor is the wiser. In God, however, it means only procession of origin, which is according to equality, as explained above (Q. 42, AA. 4, 6). (I, q. 43, a. 1, ad 1)

Again, in terms of having been sent in relation to the sender and in His eternal relation to His principle of origin, the Son is not less than the Father or subject to the Father:

For source and authority signify in God nothing but the principle of origin. (I, q. 33, a. 4, ad 1)


[A]lthough we attribute to the Father something of authority by reason of His being the principle, still we do not attribute any kind of subjection or inferiority to the Son, or to the Holy Ghost, to avoid any occasion of error. (I, q. 33, a. 1, ad 2)

But, alternatively, as “the one sent to the end whereto he is sent,” He is indeed less than and subject to the Father:

Our Lord says (John 14:28), “The Father is greater than I”; and Augustine says (De Trin. i, 7): “It is not without reason that the Scripture mentions both, that the Son is equal to the Father and the Father greater than the Son, for the first is said on account of the form of God, and the second on account of the form of a servant, without any confusion.” Now the less is subject to the greater. Therefore in the form of a servant Christ is subject to the Father. (III, q. 20, a. 1)

Obedience of the Son

We had passed over the visible mission of the Holy Spirit above, wherein the Spirit is said to be sent by His appearing to men, most significantly on the Day of Pentacost. Both the Son and the Spirit have a visible mission. But Aquinas notes that the Holy Spirit is never referred to as less than the Father, even in His visible, temporal mission. We read,

The Son assumed the visible creature, wherein He appeared, into the unity of His person, so that whatever can be said of that creature can be said of the Son of God; and so, by reason of the nature assumed, the Son is called less than the Father. But the Holy Ghost did not assume the visible creature, in which He appeared, into the unity of His person; so that what is said of it cannot be predicated of Him. Hence He cannot be called less than the Father by reason of any visible creature. (I, q. 43, a. 7, ad 1)

To this point, Aquinas has both said that sending, in relation to origin, does not imply subjection to the sender unless the sender is greater than the sent, and he here shows further that what allows us to speak of the Son as less than the Father, and therefore subject to the Father, is His assumption of the lesser human nature. Being sent only implies subjection of one who is less than the sender; the Son is only less than the sender by His union with a new and lesser nature. Since the Holy Spirit did not assume a lesser nature, He is not less than the Father or subject to the Father by being sent, even temporally and visibly. For Aquinas, equality and inequality, greater and lesser, have only to do with distinction of natures, and nothing to do with relation of origin (“it is not by reason of the relations that we consider either equality or inequality in God…”[I, q. 35, a. 2]).

The incarnate Son is not equal with the Father, according to His human nature. The Son is in fact less than the Father, according to His human nature. It is only on these terms—the temporal, visible, and enfleshed mission—that He is obedient to the Father; for subjection is due to the relation of lesser nature to greater nature, for “from the divinely instituted natural order, lower things of nature have necessarily to be subordinate to the motion of higher things” (II-II, q. 140, a. 1). There is no inequality, no greater or lesser, no subjection, nor obedience in the “the habitude of the one sent to the sender”; there is only subjection in “the one sent to the end whereto he is sent,” by addition of the unequal and lesser nature.

For Aquinas, obedience is in fact the “proper act” of man—the act most proper to one who is a creature and by nature less than God, yet equipped with the faculty of intellect and understanding. Thus, it is by assuming true human nature that the Son participates in the proper act of being human, becoming obedient to the Father. We see this in the following, wherein Aquinas describes just what it is about the Son’s assumption of the human nature that makes Him subject to the Father:

Whoever has a nature is competent to have what is proper to that nature. Now human nature from its beginning has a threefold subjection to God. The first regards the degree of goodness, inasmuch as the Divine Nature is the very essence of goodness as is clear from Dionysius (Div. Nom. i) while a created nature has a participation of the Divine goodness, being subject, so to say, to the rays of this goodness. Secondly, human nature is subject to God, as regards God’s power, inasmuch as human nature, even as every creature, is subject to the operation of the Divine ordinance. Thirdly, human nature is especially subject to God through its proper act, inasmuch as by its own will it obeys His command. This triple subjection to God Christ professes of Himself. (III, q. 20, a. 1)

The Son’s obedience is according to that in which He is subject to the divine ordinance and power, the proper subjection of his will to the command of God; “just as all natural things are subject to the divine motion by a natural necessity so too all wills, by a kind of necessity of justice, are bound to obey the divine command” (II-II, q. 104, a. 4).

And this assumption of obedience is closely related to humility. We read in the letter to the Philippians that the Son’s becoming obedient to the Father is an unnatural humbling of His person: “Let this mind be in you which was also in Christ Jesus, who, being in the form of God, did not consider it robbery to be equal with God, but made Himself of no reputation, taking the form of a bondservant, and coming in the likeness of men. And being found in appearance as a man, He humbled Himself and became obedient to the point of death, even the death of the cross.” (Phil. 2:5-8). In the same way that obedience is the “proper act” of manhood, so humility is for Aquinas especially proper to humanity, and “seems especially to regard the subjection of man to God” as “the foundation of the spiritual edifice” (II-II, q. 161, a. 5, ad 2). But again, due to the divine perfection of His Godhead, the Son of God has no humility accorded to His eternal nature:

A thing is said to be perfect in two ways. First absolutely; such a thing contains no defect, neither in its nature nor in respect of anything else, and thus God alone is perfect. To Him humility is fitting, not as regards His Divine nature, but only as regards His assumed nature. (II-II, q. 161, a. 1, ad 4)

And last of all, though this humbling to obedience is contrary to the nature of the Son of God, and is only assumed according to His human nature, it is nevertheless fitting that He submit to the Father in time. Why? For our salvation.

It was befitting that Christ should suffer out of obedience. First of all, because it was in keeping with human justification, that “as by the disobedience of one man, many were made sinners: so also by the obedience of one, many shall be made just,” as is written Rom. 5:19. Secondly, it was suitable for reconciling man with God: hence it is written (Rom. 5:10): “We are reconciled to God by the death of His Son,” in so far as Christ’s death was a most acceptable sacrifice to God, according to Eph. 5:2: “He delivered Himself for us an oblation and a sacrifice to God for an odor of sweetness.” Now obedience is preferred to all sacrifices. according to 1 Kings 15:22: “Obedience is better than sacrifices.” Therefore it was fitting that the sacrifice of Christ’s Passion and death should proceed from obedience. Thirdly, it was in keeping with His victory whereby He triumphed over death and its author; because a soldier cannot conquer unless he obey his captain. And so the Man-Christ secured the victory through being obedient to God, according to Prov. 21:28: “An obedient man shall speak of victory.” (III, q. 47, a. 2)

Mediate Conclusion

To conclude, I believe the above makes for a good basis going forward. I have passed over many pertinent issues, e.g., in what way the Son sends Himself and is subject to Himself, and other like juicy issues; but these will all come to the fore in subsequent posts as we deal with counter proposals and objections.

For now, it is enough to conclude with Aquinas “that Christ is simply greatest, Lord, Ruler” according to His eternal procession from the Father, “whereas to be subject or servant or less is to be attributed to Him with the qualification, in His human nature” (III, q. 20, a. 2). How do we know this? We know this because “[i]n the divine persons there is nothing for us to consider but the essence which they have in common and the relations in which they are distinct,” and the Son is equal with the Father in nature and equal in the relation of origin by which they are distinct. The Son is only less than the Father in the habitude of “the one sent to the end whereto he is sent”; that is, in His visible, temporal incarnate mission. Procession becomes submission only when a greater or less is added. Greater and less pertains only to distinction of natures. The nature of Godhead is one and perfect, with supreme authority. But the nature of man is less, and its “proper act” is obedience, by humility, due to disparity of nature. The Son of God assumed the latter into His own person in time in order to redeem humanity, not as a property of His eternal nature, nor as property of His eternal relation to the Father.


2 thoughts on “Thomas Aquinas on the Obedience of the Son (re: “The Obedience of the Eternal Son,” Part 3)

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