Aquinas on Christ's Unity: Whether Christ as Man Is a Person, and Whether Christ Is One or Two (Summa III, q.16–17)

Orientation #

He is finishing the article on whether Christ as man is a person, then takes up q.17 (proemium and a.1), noting that q.18 will treat Christ’s willing and q.19 his doing. He says at the end: “we’ll meet again next week, same time, same place.”

The class, in order #

1. Definition as a major work of the mind (“a major work of the mind”) #

Point: a good definition solves difficulties by itself.

• “Capable of laughter” follows from rational animal: because animal he can make the sounds, but more primarily because he has reason he can see the absurdity of a thing — e.g. the notion that animals should be represented in court by a lawyer, the cow suing the man who eats him.
• Once you have the right definition, “it solved all the difficulties.”
• He admires Boethius for the definition of person and for the definition of eternity (Prima Pars); calls him “a major mind.”
• His own case: setting out, in imitation of the lost part of Aristotle’s Poetics, to define comedy — “it took me a long time.”
• Aristotle’s Topics — a transliteration, not a translation; it means “about places” where one looks for dialectical arguments. Eight books, all ordered to definition: whether something belongs to a thing; whether essentially or outside; whether to it alone; and a further book on what else definition requires.
• Shakespeare’s definition of reason, “the ability for a large discourse, looking before and after”: only gradually did he see how good it was; and having the words of a definition is not understanding it — you must understand “discourse,” then “large.”
• Most people use “definition” loosely, for some explanation of what they mean by their words. In his friendship class, asked “what is love?”, students said “a feeling” — but anger is a feeling too; is anger love?
• Definitions of statement and of syllogism are major accomplishments; most philosophers cannot define a genus out of the blue, “and the whole rest of philosophy depends upon having a distinct knowledge of what a genus is” — even theology (whether God is in a genus; carrying “wisdom” over to God, you drop the genus and keep the difference).
• Fr. Boulet at Laval drummed this in; his first semester there was the Isagoge with Albert the Great’s 200-page paraphrase. He asked his colleagues how many had read the Isagoge: none, and some did not know what it was — like Acts, “we have not even heard that there is a Holy Spirit.”
• On Thomas’s article on the definition of eternity: each objection attacks one part of the definition, each is answered — “he’s very stingy there,” letting no word of the definition go out.

2. The objections of q.16 a.12 stated (“Christ, according as he is man, is a person”) #

• Obj. from the definition: Christ as man is an individual substance of a rational nature, therefore a person.
• Third objection: Christ as man is a res naturae of human nature, a suppositum and hypostasis (Latin and Greek words of the same thing); but every such is a person.
• Sed contra: Christ as man is not an eternal person; so there would be two persons in Christ, one in time and one eternal, which is erroneous.
• Aside on solitude: “I should really leave you for another day… in your cell, locked up… It’s the only way to clear a man’s mind” — no daily newspaper.

3. Digression: “term,” “proposition,” and the force of custom (“Define your terms”) #

• “Term” comes from the logic of the third act: a syllogism has two premises and three terms (Greek: limits); because a limit may be expressed by one word, “term” came to be used for a name. Strictly we should say “define your names” or “define your words.”
• Likewise “proposition” originally meant a premise — propositio, placed before, because a conclusion is to be drawn. So proposition names the statement only as used in a syllogism. He prefers “statement” for the logic of the second act. Compare: I am a man, and I am a father because I give rise to somebody.
• Why the borrowing: reasoning seems the act most characteristic of reason, so its vocabulary spreads. Thomas himself follows the custom.
• Force of custom, further: people call the blessing before meals “grace,” though grace is the thanksgiving that should be said after the meal — “but usually after the meal you’re not in the very religious state.” And Aristotle: even what we know to be unreasonable we go on following — the scientist still says “the sun rose at six.”

4. The body of a.12: the three senses (“by reason of the suppositum, or by reason of the nature”) #

“Man” placed in reduplication (“as he is man”) is taken either by reason of the suppositum or by reason of the nature.

1. By reason of the suppositum: manifestly Christ as man is a person, since the suppositum of the human nature is nothing other than the Person of the Son of God. (Parallel: “the Word was toward God” takes “God” for a suppositum; “God is eternal” takes it by reason of the nature.)
2. By reason of the nature, first way — that it belongs to human nature to be in some person: true, for everything subsisting in human nature is a person.
3. By reason of the nature, second way — that a proper personhood is owed to the human nature in Christ, caused from the principles of human nature, as yours and mine is: false, because that nature is not existing by itself apart [from the divine person].

• Aside: “most men are not good at seeing a distinction” (Aristotle), and Thomas is always seeing one. A Dominican’s maxim: “Never affirm, seldom deny, always distinguish” — an exaggeration, but with truth in it.

His “magisterial explanation”: a line has an endpoint. A second line drawn apart has its own endpoint; but a second line drawn to that same point has an endpoint which is the endpoint of the first line. So the human nature has a personal terminus, but it is the divine Person. (Aside: the nun’s conference paper “Audiovisual Aids to Metaphysics,” at which the audience spontaneously burst out laughing.)

5. The three replies (“but this is private, it belongs to this man alone”) #

• Ad 1: to every man it belongs to be a person, since everyone subsisting in human nature is a person; but it is private to the man Christ that the person subsisting in his human nature is not caused from the principles of human nature but is eternal. He insists proprium here is better rendered “private,” not “proper.” So in one way he is a person as man, in another way not — “in that way, he’s not like us.”
• Ad 2: “individual substance” in Boethius’s definition implies a complete substance subsisting by itself, separated from others — otherwise a man’s hand could be called a person, since it is something substantial and individual; but it exists in another. So the human nature in Christ, existing in the divine Person, is not its own person, though it can still be called individual and a singular thing.
• Ad 3: as person signifies something complete subsisting by itself in a rational nature, so hypostasis, suppositum and res naturae signify in the genus of substance something subsisting by itself; hence what is denied of “person” here must be denied of all of them.

6. What a proemium is (“pave the way, not leading into”) #

• “Introduction” means leading into: college courses “Introduction to Economics” lead you into the subject. A proemium means to pave the way: it states what you are aiming at, and only then do you pursue it and lead the person in. He likes the proemium to Verbum Dei of Vatican II, short in the official Latin, though his first English edition said “introduction.”
• Isagoge is etymologically the same as “introduction” — Porphyry leading you into logic, especially the logic of the first act; and that introduction has its own magnificent proemium: to know what genus, difference, species, property and accident are is necessary, Chrysaorius, not only for the Categories of Aristotle “which is the reason why the question arose,” but for definition, division and demonstration.
  • [He first says the Isagoge is Boethius’s, then throughout treats it as Porphyry’s — a self-correction to keep.]
• Commentaries: Albert the Great’s 200-page work (De praedicabilibus), Cajetan’s beautiful commentary (Cajetan’s Summa commentary is printed in the Leonine), later Greeks, Muslims, Christians.
• What Porphyry did: brought together Aristotle’s teaching on these, scattered (genus is in Physics V, species elsewhere), so that you see a whole picture you would not see otherwise.

7. The proemium of q.17 (“about those things which belong to unity in Christ in general”) #

• Unity or plurality in particular is settled in its own places: it has been determined above that in Christ there is not one knowledge (beatific vision, infused knowledge, experiential knowledge), and later that in him there is not only one birth.
• So: first unity according to his being (q.17); second as regards his willing (q.18); third as regards his doing (q.19).
• q.17 asks two things: whether Christ is one or two; and whether in Christ there is only one being.
• Asides: foundation day of the house is the Nativity of Mary, thirty-one years ago; the pastor asking the grade-school children what “Nativity” means.

8. The seven objections of q.17 a.1 (“whether Christ is one or two”) #

1. Augustine, De Trinitate I: because the form of God took the form of a servant, he is both God (on account of God taking) and man (on account of the man taken); but “both” cannot be said save of two. — Student asks whether Augustine refers to the Philippians kenosis, and how self-emptying involves becoming two; answer: he emptied himself and took on the form of a man, so he took on both forms; more simply, he was then both God and man — one became two.
2. Augustine, Enchiridion: whoever is aliud et aliud is two; Christ is other on account of the Word, other on account of the man.
3. Christ is not only man, else he would be a pure man and not God; so he is something other than man.
4. Christ is something that is the Father (God) and something that is not the Father (man); so he is something and something, so two.

• He notes “an unusual number of objections here.”

5. As the Trinity has three persons in one nature, so the Incarnation two natures in one person — the two mysteries are in a way contrary. On account of unity of nature, notwithstanding distinct persons, we say “I and the Father are one” (John 10); so notwithstanding unity of person, on account of duality of natures, Christ is two. He calls this “kind of neat,” since it touches that contrariety.
6. Physics III: one and two are said denominatively; Christ has a duality of natures. (Denominative, from Categories ch. 1: not “you are justice” but “you are just”; not health but healthy.)
7. As an accidental form makes something other (in quality), so a substantial form makes it other in kind, as Porphyry says; but in Christ there are two substantial natures. — Genus is “one name said of many things other in kind, signifying what it is”; the predicables concern the way something is said of something.

Digression on the heresies and the mean: in the Trinity, error goes either to three natures for three persons (more than the truth) or one person for one nature (less); in the Incarnation, two persons for two natures (Nestorius) or one nature for one person. “Truth is in between two extremes.” Shakespeare, King Lear: “all my reports go with the modest truth… nor more nor clipped but so”; and Falstaff on those who say more or less than the truth. The courtroom oath: the truth (nothing added), the whole truth (nothing subtracted), and nothing but the truth. Likeness to moral virtue: Nicomachean Ethics II, a habit with choice in the middle towards us as determined by right reason — courage between foolhardiness and cowardice, not equidistant. And Physics VIII: all at rest (Parmenides, Leucippus), all in motion (Heraclitus), or the truth between — the extreme positions cannot explain why anyone would hold the other.

Aside (student: “split personality?”): no — one person; and on Christ’s departure in John: unless I go the Spirit will not be sent; Thomas and the Fathers suggest that had Christ remained we would have had a hard time accepting his divinity, the apostles being attached to his familiar humanness — “show us the Father and it is enough.”

9. Sed contra and the body: nature is not said of the suppositum (“am I human nature?”) #

• Sed contra: Boethius, in the book on the two natures (the source of the definition of person): everything that is, in so far as it is, is one; we confess Christ to be; therefore Christ is one. “Beautiful” — and note that in the Middle Ages the respect for Boethius makes you think twice when he says the opposite.
• Body: a nature considered by itself, signified in the abstract, cannot truly be said of the suppositum or person — except in God, where what is and that by which it is do not differ. Am I human nature? No; I have it. I am a logician, not logic; healthy, not health; a woman may be called “a beauty,” but figuratively — beauty is that by which she is beautiful.
• In Christ, the divine nature can be said of him both in the abstract and in the concrete: the Son of God who stands under the name Christ is the divine nature, and is God. (Christ in John: “I am the way, the truth, and the life” — the abstract word.) But human nature can be said of him only in the concrete, as signifying in the underlying suppositum: he is said to be a man, not to be manhood.
• Why: from the treatment of the divine names — the proper object of our reason is the what-it-is of something sensed or imagined, and in such things what they are and the thing are not the same. Deitas and Deus are really the same, but differ in mode of signifying: God signifies as having the divine nature, deity as that by which he is God. Hence every name has a defect: “deity” signifies rather that by which he is, “God” signifies as though something composed, like in us — “in some sense no name is adequate.”
• The rule: “God is whatever he has” — but “that ain’t true about me”: I have human nature but I am not what I have.
• Further distinction: “man” implies having humanity indistinctly, as “God” implies having deity indistinctly (hence “God” can stand for Father, Son or Holy Spirit); “Jesus” or “Peter” implies having humanity distinctly, under determined individual properties — as “the Son of God” implies one having the divine nature under a definite personal property. “Wow, what a man!”
• Aside on rereading: he reads a passage, looks at it again the next morning with a clear mind and sees more. De Koninck: “if you think you understood everything you read here, that’s a sign you’ve understood nothing” — supremely so of the Trinity. Thomas on the reasons for the Incarnation: the more you consider it, the more wonderful and the more profound the reasons appear. C. S. Lewis on the man who “read Homer” once; you can go back again and again. And: Western civilization begins with the Iliad.
• Conclusion of the body: the duality in Christ is placed about the natures; if both natures in the abstract could be said of Christ, it would follow that Christ was two. But only the divine nature can be so said. Since the natures are said of Christ only as signified in the suppositum, the predicating of “one” or “two” follows the notion of the suppositum. Some laid down two supposita but one person (person being a complete suppositum by the ultimate completion), and so said Christ is two in the neuter but one in the masculine — the neuter genus designating something unformed and imperfect, the masculine something formed and perfect. The Nestorians, laying down two persons, said two in the masculine also. But since we place in Christ one person and one suppositum — person and suppositum differing in that suppositum is more general, person a suppositum of a rational nature — Christ is one masculine and also one neuter.
• Asides: the etymology of “neuter” as ne-uter, “not from the uterus” [he is unsure whether it is Isidore’s]; and scripture scholars who have Christ doubting whether he is God and gradually realizing it — “imagine what a feeling he had when he finally realized.”

10. Replies to the first three objections (“it holds itself on the side of the subject”) #

• Ad 1: Augustine’s utrumque is not on the side of the predicate (as if Christ is both) but on the side of the subject; and it stands not for two supposita but for two names signifying two natures in the concrete: both, God and man, is God on account of God taking both natures; and both, God and man, is man on account of the man assumed. “I think I’ll think about that another day — that’s a little bit dense even for this guy.”
• Ad 2: “Christ is aliud et aliud” must be expounded as meaning he has another and another nature; so Augustine in Contra Felicianum: “in the mediator of God and man, other is the Son of God, other the son of man” — aliud for the distinction of substance of the two natures, not alius for the unity of person. In English the grammar is lost — an argument for teaching Latin. Vincent of Lérins: in the Creator alius et alius, non aliud et aliud; in the Savior aliud et aliud, non alius et alius. Gregory Nazianzen, Epistle to Cledonius: if one must speak compendiously — “what’s Thomas’s work called? the Compendium of Theology, written for his friend” — aliud quidem et aliud those of which the Savior is, the invisible not the same as the visible, the timeless not the same as what is under time; but not alius et alius, God forbid, for these two are one.
• Ad 3: “Christ is only man” is false, because “only” excludes not another suppositum but another nature, since terms placed in the predicate hold themselves as form. If something be added drawing it to the suppositum — “Christ is only that which is a man” — the speech would be true. Nor does it follow that he is aliud than man, since aliud, being the relative of diverse substance, properly refers to the suppositum; so it would follow only that he has another nature.
  • Why the predicate holds itself as form: in “man is an animal,” the subject is like matter, the predicate like form; we even put the particular under the universal on the board, as matter under form. Why reasonable? His nephew, before he was married, knocked over the towers he built; but when the tower was built taller than him he pointed at it in admiration and did not knock it over — we think of the agent as acting upon what is below, as it is easier to pound downward than to hammer upward. Hence he translates actio and passio as “acting upon” and “undergoing.” The agent acting upon matter gives it a form, so form is above matter; and the universal is like a form realizable in many matters (the form of this table in many tables). Hence the more universal is predicated of the less — you say “a dog is an animal,” not the reverse.
• He breaks off at 4:20 for an appointment; “there might be more reasons” for the last point than he gave.

His words #

• “individua substantia” — individual substance in Boethius’s definition; implies a complete substance subsisting by itself, separated from others.
• “reduplication” — the “as he is man” construction, taken either by reason of the suppositum or by reason of the nature.
• “private” — his rendering of proprium, preferred to “proper”: what belongs to this man alone.
• “res naturae” — a thing of a nature; with hypostasis and suppositum, something subsisting by itself in the genus of substance.
• “premium” [ed.: proemium] — “pave the way,” stating what you aim at; opposed to “introduction,” a leading-into.
• “the logic of the first / second / third act” — the Isagoge and predicables; statement; syllogism. [ed.: the three acts of the mind]
• “statement” — preferred to “proposition,” since propositio properly means a premise.
• “natural hearing” — [ed.: Aristotle’s Physics], cited for the eighth book on rest and motion.
• “denominative” — “you are just,” not “you are justice.”
• “acting upon” / “undergoing” — his translations of actio and passio.
• “God is whatever he has” — true of God only, not of me.

Texts #

Read in class

• Thomas Aquinas, Summa Theologiae III, q. 16, a. 12 — objections (from the definition of person; from hypostasis/suppositum/res naturae), sed contra, body, replies 1–3.
• Thomas Aquinas, ST III, q. 17, proemium.
• Thomas Aquinas, ST III, q. 17, a. 1 — seven objections, sed contra (Boethius), body, replies 1–3.
• Porphyry, Isagoge, proemium (the address to Chrysaorius).

Mentioned

• Boethius, De duabus naturis; his definition of eternity (used in ST I).
• Augustine, De Trinitate I; Enchiridion; Contra Felicianum.
• Vincent of Lérins; Gregory Nazianzen, Epistle to Cledonius.
• Aristotle, Topics (eight books); Categories ch. 1; Physics III and VIII; Nicomachean Ethics II; Poetics (lost part on comedy).
• Albert the Great, De praedicabilibus; Cajetan on the Isagoge and on the Summa.
• Thomas, Compendium of Theology; his treatment of the divine names, of God in a genus, of Christ’s several kinds of knowledge, and of the reasons for the Incarnation.
• John 10 (“I and the Father are one”); John 14 (“show us the Father”); John 14:6; Philippians (kenosis) — raised by a student; Acts (the Holy Spirit unheard of).
• Shakespeare, King Lear (“all my reports go with the modest truth”); his definition of reason (“large discourse, looking before and after”); Falstaff; Vatican II, Dei Verbum; Homer’s Iliad; C. S. Lewis; De Koninck.

His questions #

• Is Christ, as he is man, a person? Yes if “man” is taken for the suppositum, or as meaning human nature must subsist in some person; no if it means a personhood caused from the principles of human nature.
• Why can’t the hand of a man be called a person, since it is individual and substantial? Because “individual substance” in the definition means complete and subsisting by itself, not existing in another.
• Is Christ one or two? One — in the masculine and in the neuter — because the duality is of the natures, and the number follows the suppositum, of which there is one.
• If someone is both God and man, is he one or two? The students say two; the reply: utrumque stands on the side of the subject, for two names signifying two natures in the concrete, not for two supposita.
• Am I human nature? Am I logic? Am I health? No — I have human nature; logic is that by which I am a logician. Only in God is what he is the same as that by which he is.
• Why do we call the subject “subject” and take the predicate as form? Because the agent acts upon what lies under, and the form comes to the matter from the agent; so the universal, like a form, is predicated of the less universal.
• What does proprium mean here? Not “proper” but “private” — belonging to this man alone.
• What is the difference between a proemium and an introduction? A proemium paves the way by stating the aim; an introduction leads you into the subject.