Review: Thomas Aquinas, Summa Theologiae

This is one of the great books of all time.  It is basically a Q&A on various masters’ theses.  It is relentless in its pursuit of logical questions (and of apparently inane tangents).  The great thing about Thomas is that you can’t take anything for granted.  The small proof 400 pages ago will be the key to a subtle argument.

Thomas was a victim of his own success.  Few read him beyond the 5 Proofs, and I suspect those proofs weren’t all that interesting for him and his audience.

On God

Thomas: each thing has its own act of being; real apart from the distinct acts of existence.

God: existence as necessary being; his act of existence needs no cause of existence.  Pure act of being.

As Qui Est God has no genus, otherwise he would have an essence distinct from his act of being.  For God, to be is to be good.  His being and goodness are identical.

God knows himself perfectly and he knows himself immediately.

Does God know possibles?

  1. Concerning what might have been, he knows them by simple intelligence.

  2. God’s intelligence.  Will proceeds from intelligence.

The immediate object of divine intelligence is God.  He wills all other things by willing himself.  God’s willing of possibles doesn’t necessarily create them.

  1. a will is an action completely interior to the one willing.

  2. God doesn’t necessarily create existence by “willing,” but only through one of the divine actions whose terminus is an effect exterior to God

Treatise on Law

Thomas only devotes one question specifically about natural law in the middle of 19 questions.  More importantly, Thomas never abstracts natural law (which is usually exactly what his critics and defenders do).  Natural law is oriented back to the eternal law and the divine providence (ST 1-2. 90).

A short definition: “Law (lex) is something rational (aliquid rationes) directed to the common good by those who are responsible for that community” (Kerr 105).

  1. Eternal

  2. Natural

  3. Human

  4. Divine

(2)-(4) are how the eternal law is worked out in providence. You can’t separate natural law from discussions of God.


(1) For Thomas grace is two things: the work of God upon the soul and the effect of that action.

Two things are considered in the soul: the essence of the soul and the work of its powers.  The form of the soul is intellectual in orientation

The Subsistence of the Soul

Thomas: Nothing acts so far as it is in act, and nothing acts except that whereby it is in act. The soul is the form of the thing.  The soul’s powers are its mind and will.

(2) Form is the act in which a thing has its being and subsistence.

For Aquinas justification, in short, will consist of reorienting the intellect back to God’s proper order.  It is important to keep in mind that the soul is a spiritual substance that is intellectual in character (and this isn’t unique to Aquinas.  This is roughly the historic Christian position).

(3) Grace finds its seat in the essence of the soul, not in the powers.

What metaphor does Aquinas use to explain the nature of this grace infused into the soul?  Light.  Light, however, suggests an intellectual range.  This would place grace somewhere else than the essence of the soul–some place like the intellectual powers of mind and will.

In short, God moves all things (in justification) according to the proper mode of each.  It looks like this:

Infusion of justifying grace → a movement of free choice → forgiveness of sin

Part 2 of Second Part

Scope: This is Thomas’s course on virtue ethics.  Much is good, much bad.

The glory of the soul, which is the enjoyment of God, is the principle object, not the glory of the body (II.2.18.2).  True to an extent, but it’s not clear why Thomas needs the resurrection for this.

On Charity

There is a kind of friendship based on the communication between God and man (II.2.23.1).

Human acts are good as they are regulated by their due rule and measure (23.4).

Charity is infused in us (24.2). Every act of charity merits everlasting life (II.2.24.6). Mortal sin destroys charity entirely (24.10, 12). The spiritual life is an effect of charity.  Mortal sin destroys that.

Charity is capable of reflecting on itself.  The intellect reflects on the universal good, and since to will is a good, man can will himself to will.  Love, therefore, is a spontaneous movement of the lover to the thing loved (25.2).

While we are obligated to love our enemies, we are not obligated to show them all effects of love (25.9).

Key point: One’s obligation to love another is proportionate to the gravity of the sin one commits in acting against that love (2.26.6).

On Giving Alms

* Some are punished eternally for not giving alms (2.32.5).  By contrast, “almsdeeds deserve to be rewarded eternally through the merit of the recipient, who prays for the giver” (2.32.9).

* God gives us ownership of temporal goods but the use of them is directed to helping our neighbor).

Just War

Standard Augustinian stuff. Thomas gives several conditions: a) authority of the sovereign or leader waging it; b) just cause; c) right intentions.  Tyrannical governments are not just because they threaten the common weal (2.42.2).

The Glory of Monastic Life

It’s possible to go to heaven without being a monk, but it’s a lot harder.  Thomas speaks of being perfect.  He doesn’t mean sinless.  A thing’s perfection, rather, relates to charity, the consequences from charity, etc (2.186.3).

Various Nota Bene

* The church can compel secular power with regard to heresy and schism (2.39.4).

* Married sex increases concupiscence and is the contrary of the passage “cleansing ourselves from all defilement of flesh and spirit” (2.186.4).  He quotes Augustine to the effect that when married people caress one another they are “cast down from manly mind” (Solil. 1.10).  Sorry, Reformed Thomists, but this is where the Reformation is a clear improvement.  Indeed, Thomas goes on to say that “perpetual continence is required for religious perfection.”

* Contrary to claims by Dutch Calvinists, there is no cultural activity in heaven (2.181.4).

Thomas’s Linguistic Fallacies

This type of thinking was quite common until recently.  It’s still painful to read, though.  For example, wisdom (sapientia) connotes sweetness because it comes from the word “saporem” (2.45.2).

Further, Thomas commits the word = concept fallacy.  For Thomas “religion” means “religious orders.”  Therefore, when James talks about “religion pure and undefiled,” this gives the sanction for man entering into religious orders (2.188.2).

A virtue is an operative habit (I-II, q.55, a2).

The Order of Love

Wherever there is a principle, there is an order.  Charity is of a “last end.”  Therefore, it has reference to a “First Principle” (26.1).

Christology: 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).

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.

Treatise on the Sacraments

A sacrament is ordained to signify our sanctification (III.60.3). The cause of our sanctification is Christ’s passion.  The form is grace and the virtues.  The End is eternal life.

Do the sacraments cause grace?  Thomas says they do by distinguishing a principal cause and an instrumental cause (III.62.1). The principal cause works by the power of the form.  The instrumental is the cause by which it is moved.

The soul’s powers flow from its essence, “so from grace there flow certain perfections into the powers of the soul, which are called virtues and gifts” (III.62.2). Grace, accordingly, is in the sacrament as an instrumental power.

Sacramental grace: the principal efficient cause is God himself. This grace is to take away defects consequent on past sins, which hinder divine worship.

The sacraments, especially Orders, imprint a character on the soul.  (Thomas then has some horrendous exegesis of Hebrews 1, where he reads medieval Latin understandings of “character” into the koine Greeek.) The important part is that Thomas equates character and sealing of the Holy Spirit (cf. Schaff on this point; I think volume on Nicene Christianity).

The inward effect of all sacraments is justification (III.64.1).


The Empyrean heaven is a corporeal place (Supp. III.69.1).  It will have the souls of the righteous.  Venial sin is cleansed in purgatory.  Some souls can come and visit.

Thomas gives the standard medieval arguments for praying for the dead, and in reverse the saints can pray for us.  Here is where it gets tricky.  In response to the question, “Why can’t we just go to God?” Thomas answers, “There is a divine order where ‘the last should be led to God by those that are midway between’” (quoting Ps. Dionysius, Supp. III.72.2).  If pressed strictly, Thomas must admit there is no logical reason for us ever to pray to God.  He doesn’t forbid it, but given the above ontology we shouldn’t.  Indeed, he goes on to say that the “perfection of the universe demands” we go through saints.

Here’s the next problem: by what standard do I know that a deceased is a saint and not in Purgatory?  Presumably he would say the Church has decreed it.  Okay, where did the church gain that access to knowledge?

In terms of the signs preceding the End Times, he follows Augustine.

Notes of Interest

When Mary gave birth, Jesus didn’t break through her birth canal and damage the virginal purity (Supp. III.83.3).

On Hell

The saints see perfectly the sufferings of the damned (Supp. III.94.3). Divine justice and their own deliverance will indeed by a direct cause of the saints Joy at seeing the sufferings of the damned.


This book will change you.  It won’t necessarily change your theology, but you will grow in intellectual virtue by reading through it.  Thomas forces you to always work with the implications and connections.


4 thoughts on “Review: Thomas Aquinas, Summa Theologiae

  1. Did you read the part where he gives prostitution a Pass? The Vatican to this day has brothels for priests like Aquinas to this very day. Of course they cater to both Herero and homosexual priests.
    What about his argument that since Salvation is an infinite gain, that the Catholics can utilize finite evil in order to increase their Fold. This allows for the murder of innocent Jews and others based on it. If they don’t convert, by killing them you save souls from Jewish heresies.
    I think they should have hung Aquinas the ignorant asshole!


    • Yep. I’m familiar with the brothel part; I just didn’t quote everything in the review. As to murdering Jews, he actually says they can practice their religion in a Christian commonwealth (II-II Q. 10, Art 11).


      • He said that not just about Jews but anybody! As long as infinite gain vs finite evil! This justifies real world atrocities!


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