Thomas Aquinas: Summa Third Part, on Christology

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Puritanboard Clerk
It's impossible to review Thomas in one post. Part 1 dealt with God and creation. I-II with Natural Law; II-II with Virtue Ethics. Now we get to the mystery of the Incarnation.

Motive of the Incarnation:
  1. The incarnation took place to deal with the Fall
  2. Incarnation
  3. There is a tension, though: Aquinas holds that God is the diffusive Good, which seems to suggest that The Incarnation would have happened anyway. Yet most fathers hold that it came about because of sin.

On Person and Nature

Nature designates the essence of the species. A suppositum is the whole which includes the nature as “its formal part” (III.2.2).

Something’s “assumption” includes the principle and term of the act (3.3.1). The principle of the assumption is the divine nature itself. The term is the Person in whom it is considered to be. The act of the assumption proceeds from the divine power, which is common to the three persons. The term of the assumption, being the second person, isn’t common to the three.

Thomas argues that Christ didn’t assume a generic human nature, since human nature cannot be apart from sensible matter (3.4.4).

Thomas posits an archetypal theology within the union of the God-man, saying “from the moment of his conception Christ saw God’s essence fully” (3.7.3). This is important for Thomas, for on his gloss, “The soul of Christ had to be perfected by a knowledge which would be its proper perfection” (3.9.1). Indeed, the soul of Christ is perfected with the beatific knowledge. Thomas isn’t saying, however, that the soul/human nature of Christ simpliciter sees the divine essence.

Christ’s human soul has access to the divine nature but doesn’t comprehend it totally.

On necessity in Christ: There are two kinds of necessity. One is by constraint via an external agent. The other is a natural necessity. In the latter respect was Christ subject to necessity.

Christ did not have concupiscence (3.15.2). Thomas goes on to say that perfection of virtue does not exclude passibility of body but only fomes. In other words, Christ did not lust after the pleasurable things against the order of reason.

Now to Christology proper. The person of the Son of God is the suppositum of human nature. For the most part, suppositum functions similar to hypostasis, so why doesn’t Thomas call it hypostasis? I think his using “suppositum” allows him to affirm “one person” of the Son, pace Nestorius, yet acknowledge a human dimension to the Son’s person. A suppositum is the existing hypostasis.

Why is this important? If we take phrases like “Christ is God” or “this Man is God,” then strictly speaking it isn’t true. By “Christ” do we mean the eternal Son, the human nature, both, neither? Therefore, by understanding the hypostasis as a suppositum of the Second Person, we can say the above propositions.

A hypostasis is that which has being. A nature is that by which it has being.

The Singular Man:
  1. Was the man Jesus sanctified/transformed by grace? Aquinas says yes, appealing to Isaiah 61.
  2. The Passion
    1. Cry of dereliction on the cross: The Father withdrew his protection but maintained the union (ST 3.50.2).
    2. Jesus was simultaneously viator and comprehensor. Thomas says there must have always been a continuous union because of the Trinity.
    3. Then what do we make of death, which is the severing of soul and body (if Christ maintains both human nature and divine nature, which the latter is still in union with the Father)?
      1. Neither Christ’s soul nor body was separated from the Word of God (3.50.3).
      2. However, Christ's soul did separate from his body in death. That's part of the definition of dying, yet neither body nor soul were severed from the Logos.
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