8. The Incarnation: Union in Person, Not Nature

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Lecture Notes

Main Topics #

Three Ways Something Can Be One Thing #

Berquist examines three possible modes by which divine and human natures could be united:

1. From perfect integral things remaining (e.g., stones forming a pile)

   • Would not constitute one nature but only an accidental form
   • The divine and human natures would remain many things in act
   • Form would be artificial (like the form of a house), not substantial nature

2. From perfect things changed (like elements forming a mixed body through substantial change)

   • Impossible because divine nature is absolutely unchangeable
   • Divine nature cannot be converted into another (is incorruptible)
   • Nor can anything be converted into divine nature (is ingenible)
   • Latin mixtio means true substantial change, not mere mixture
   • Result would be neither God nor man, but a third species
   • Divine nature would absorb human nature (like a drop of water in an ocean)
   • The burning bush analogy: fire does not consume the bush

3. From imperfect things (like soul and body forming a man)

   • Both divine and human natures are perfect in their own definitions
   • Cannot constitute composition by quantitative parts (divine nature is incorporeal)
   • Divine nature cannot be form of matter or body
   • Would result in a communicable species (many Christs would follow)
   • Adding differences to a nature varies the species (like numbers: subtract or add and you have a different number)

The Distinction Between Nature and Person #

Nature signifies the essence of the species—what it is—as expressed in the definition.

Person signifies an individual substance of rational nature (Boethius’s definition) that subsists or exists in itself.

Key difference in creatures (especially composite things):

• Nature is the specific essence (formal part)
• Person/suppositum is the whole individual that subsists, which includes the nature plus accidents and individuating principles
• Example: Duane Berquist is not identical to human nature; he has human nature as a formal part, but includes other things (knowledge, color, health, accidents)

In God:

• Person and nature do not differ secundum rem (in reality)
• They differ only secundum rationem (in thought)
• Divine person = divine nature; they are absolutely identical

Union Made in Person, Not in Nature #

Thomas’s argument: If human nature is united to the Word, it must be united in person, not in nature. Everything that exists in a person is united in that person—whether it pertains to that person’s nature or not.

The fundamental principle: If human nature is not joined to the Word in person, the entire faith of the Incarnation is undermined.

Answering the objection (that God’s person and nature are not other):

• Although divine person and nature differ only in thought (secundum rationem), not in reality
• The Word subsists in human nature without any addition to the divine nature’s definition or any change of the divine nature
• Therefore, the union is in person, not in nature
• This is similar to how pushing and being pushed are the same motion (secundum rem) but differ in how they are signified (secundum rationem)

Human Nature in Christ vs. in Us #

Objection: Human nature in us has its own personality; why not in Christ?

Answer: Personality necessarily pertains to dignity insofar as it means existing per se (by itself). However, it is more dignified for something to exist in something more perfect than to exist by itself.

Example: The sensitive power is more noble in man (joined to rational soul) than in animals (where it is the completing form).

Similarly: Human nature is more dignified in Christ because it exists in the divine person rather than having its own separate personality.

Individual Nature Without Separate Personality #

Objection: The Word assumed an individual human nature, so it must have its own personality (following Boethius’s definition).

Answer: Not every individual substance of rational nature has personality. Only that which exists per se (by itself) has personality.

Counterexample: The hand of Socrates is an individual but not a person, because it does not exist by itself but in something more perfect (the whole body).

Applied to Christ: Human nature is an individual substance, but it does not exist by itself; it exists in something more perfect—the person of God. Therefore, it does not have its own personality.

Key Arguments #

Against Union in Nature #

• Divine nature is immutable and cannot be changed (proved in Prima Pars on God’s simplicity)
• If two things change to form one nature, neither original nature remains (neither God nor man would result)
• Infinite disproportion: Human nature infinitely exceeds human nature, so one would be absorbed in the other
• Mixed bodies lose their former specific identity; Christ would be neither God nor man

For Union in Person #

• Chalcedon defined: “one and the same begotten Son, our Lord Jesus Christ” (not divided or partitioned into two persons)
• Everything predicated of a person belongs to that person: if human nature is united, it must be in person
• The Theotokos: Mary is truly mother of God (not merely mother of human nature)
• Soteriological necessity: “God died for us” must be true—only possible if human nature belongs to divine person

Why Three Arguments Are Sufficient #

Berquist notes Thomas typically stops at three arguments because:

• Three shows up often in theological and philosophical explanation
• Four arguments tend to make you forget the first one
• Three is enough for the mind to grasp the complete picture in most cases
• Examples: three evils from sin (disorder in soul, worthiness of punishment, weakness to do good)

Important Definitions #

Nature (natura): The essence of the species; what the definition signifies; what a thing is

Person (persona): An individual substance of a rational nature (Boethius); that which subsists or exists in itself

Suppositum (suppositum): That which underlies and receives predication; the individual whole that subsists

Subsistence (subsistentia): Existing per se (by itself) versus existing in something more perfect

Hypostasis (hypostasis / Greek ὑπόστασις): Etymologically “standing under”; in theological usage = person or suppositum

Secundum rem: In reality, in the thing itself

Secundum rationem: In thought, in our way of understanding

Per se: By itself, in itself

Alius et alius (masculine): Other and other (used of persons, indicating distinction of persons)

Aliud et aliud (neuter): Other and other (used of natures, indicating distinction of natures)

Mixture (mixtio): In ancient physics, true substantial change where elements cease to be what they were and a new substance is produced (stronger than English “mixture”)

Examples & Illustrations #

Geometric Analogy (Berquist’s Original) #

• Two lines meeting at a single point: The point A is the beginning of line AB (divine nature) and line AC (human nature)
• One point (indivisible) underlies both lines while remaining simple
• Illustrates one person subsisting in two natures
• Curved and straight lines meeting at a point: The lines remain distinct (cannot coincide) even though they share the same point
• Similarly: Divine and human natures remain wholly distinct but one person subsists in both

Hand of Socrates #

• The hand is an individual substance but not a person
• Exists in something more perfect (the whole body)
• Does not have separate personality because it does not exist per se
• Applied to Christ: Human nature is individual but exists in something more perfect (divine person) and thus has no separate personality

Sensing Soul in Man vs. Brute Animals #

• Sensitive power more noble in man than in animals
• Not because man has a different sensitive power, but because it is joined to rational soul
• Similarly: Human nature more dignified in Christ (joined to divine person) than in us (with separate personality)
• Man appreciates Mozart’s music; a cat ignores it and seeks meat instead
• Recollection in man: using imagination and memory to recall the past (a kind of syllogism in imagination)

Tool Analogy (From Summa Contra Gentiles) #

• Soul uses body as a joined tool (not a separate tool like a hammer)
• Divine nature uses human nature as a joined instrument
• Explains Athanasian Creed comparison: “As soul and body make one man, so God and man make one Christ”
• Distinction: Not form-matter relationship (which would be heretical), but agent-instrument relationship
• Different arts use different tools: tailor uses needle and thread; carpenter uses hammer and saw
• Tool joined to agent has excellence from the agent: human nature of Christ has efficacy not possessed by human nature apart from union

Burning Bush #

• Church Fathers: Fire represents divine nature; bush represents human nature of Christ
• Fire’s light represents God’s understanding; warmth represents God’s love; power to transform represents God’s omnipotence
• The fact that fire does not consume the bush shows divine nature does not “swallow up” human nature
• Symbolizes the mystery: divine and human natures remain distinct in the one person

Shakespeare’s Hamlet (What is a man…) #

• “What is a man if his chief good and market of his time be but to sleep and feed? A beast, no more.”
• Illustrates Aristotle’s principle (Metaphysics VIII): natures are like numbers—subtract or add and you have a different nature
• Body + life = plant; + sense = animal; + reason = man
• Mathematical analogy: “What is a three if it be half of four? Two, no more.”
• Necessary connection: between being man and what constitutes man’s chief good; between being beast and beast’s chief good
• If man’s chief good = beast’s chief good, then man = no more than beast (contradiction)

Sacrament of Confession and Curing the Soul #

• Aristotle: Body cures itself by internal powers or needs external medicine
• Soul cannot cure itself; needs something external (confession/sacrament)
• Three evils result from sin: (1) disorder in soul (turning from God to creature), (2) worthiness of punishment, (3) weakness to do good and avoid evil
• Confession addresses all three: restores order, removes punishment, restores strength

Questions Addressed #

Why cannot the union be in nature? #

• Divine nature is unchangeable; cannot be converted or changed
• If both natures changed to form one, neither would remain; result would be neither God nor man
• No balance between infinitely disproportionate natures; one would absorb the other

How does “nature” relate to “person”? #

• In creatures: person = the whole that subsists; nature = the specific essence that is a formal part of the person
• In God: they differ only in our way of understanding (secundum rationem), not in reality (secundum rem)

Does Christ lack personality? #

• Not a defect; rather, more dignified to exist in divine person than in separate personality
• Human nature does not have its own hypostasis but subsists in divine hypostasis
• All predications about Christ belong to divine person

How do we interpret patristic statements about “one nature of the divine Word”? #

• Council of the Fifth Synod (Constantinople II) clarifies: This means one person uniting flesh, not one nature constituted from two
• Cyril of Alexandria: “One incarnate nature of the divine Word” should not be understood as creating a new nature, but as the one nature of God united personally to flesh
• Those who interpret it as a new nature are anathematized

What is the relationship between Scripture, Tradition, and Magisterium? #

• Vatican II: All three are mutually necessary; no one can stand without the other two
• Military analogy: Three rifle hooks are needed to stand upright; any two cannot stand alone
• Scripture alone (sola scriptura) leads to misinterpretation of texts like “the Word was made flesh”
• Protestant ministers converting to Catholicism recognize need for Tradition and Magisterium to interpret Scripture

Notable Quotes #

“If therefore human nature is not joined to the word of God in Christ in no way, thus wholly is taken away the faith of the Incarnation, which is to undermine the whole of the Christian faith.”

“To be more dignity to something that exists in something more dignified than itself, than it exists per se.”

“Nature is not said of the underlying. So Dwayne Berkowitz is not human nature. He’s a man. But man means what has human nature.”

“One and the same point can be the beginning of a curved line and a straight line, and one and the same person subsists in two natures that remain entirely distinct.”

“In the suppositum is included both the nature of the species and there are added above this some other things that are besides or in addition to the notion of species.”