Summa Theologica means “sum of theology.”
It refers to the mammoth work by Thomas Aquinas that clocks in at over 1.6 million words when translated into English. Thomas attempted to sum up all theology in one volume. Many Christians have expressed admiration for its ideas.
Why Did Thomas Aquinas Write Summa Theologica?
Thomas Aquinas was a Dominican monk who devoted himself almost exclusively to writing. A quiet man, when Aquinas was in school, his classmates called him “the dumb ox” because of his imposing stature and slowness of speech. He more than made up for what he lacked in speech in his writing. He began writing the Summa when at age 39 and died before its completion nine years later. It is considered an unfinished work.
Dan Graves summarizes Aquinas’ early life and surprising turn to becoming a renowned scholar:
“If you’ve ever been told you are stupid, you know how Thomas felt. The boy was puffy and seemed to be a slow thinker. His quick-witted classmates had a name that exactly fitted his case. ‘Dumb Ox,’ they jeered, wrapping his stupidity and bigness into a single taunt.
Thomas ignored them. He knew what he wanted out of life. He wanted to be a godly friar and a scholar. St. Dominic had founded an order of friars who used their brains for God’s glory and Thomas saw their path as his path.
His rich family was annoyed. It would have been okay for him to become abbot of some great monastery. There was prestige in that! But a begging friar...? Thomas must change his mind. They locked him up in a tower in their high castle and told him he’d stay there until he caved in to their demands. But Thomas was as stubborn as they were. When they saw he wasn’t changing his mind, his brothers pushed a beautiful, naked courtesan into the room to tempt him. That was the last straw. Bellowing like an ox, he grabbed a blazing stick of wood from the fire and drove the screaming prostitute out.
After two years in the tower, Thomas got his way. He was allowed to rejoin the Dominicans. The “Dumb Ox” proved to be anything but dumb. Studying the logic and teachings of Aristotle, he adapted them to the use of the church. He wrote an immense summary of theology and a defense of Christian thought against the ‘gentiles.’
The greatest of the Medieval theologians, his commonsensical philosophy, known as Thomism, undergirds much of Catholic thought. He is considered one of the doctors of the Roman Church. Yet he did not consider his knowledge something to brag about. As he pointed out, there are things about God we can take only on faith because God has revealed them to us. Not opposed to reason, they are beyond reason. ‘If the only way open to use for the knowledge of God were solely that of reason, the human race would remain in the blackest shadows of ignorance.’
St. Thomas Aquinas was called to defend the unity of man’s mind. Siger of Brabant’s theology seemed to say a statement could be true in theology although false in philosophy. Aquinas won that battle. He could have become proud.
Instead, he stopped writing. What happened, according to an early biographer, was this: While saying mass on this day, December 6, 1273, the noble-minded philosopher experienced a heavenly vision. Urged to take up his pen again, he replied, “Such things have been revealed to me that all that I have written seems to me as so much straw. Now I await the end of my life.’
In the 20th century, his philosophy was revised in light of modern findings. You may meet it as neo-Thomism.”
(“Thomas Aquinas Had a Vision” by Dan Graves, MSL, published on Christianity.com on April 28, 2010)
Thomas intended the Summa as a theological primer for pastors in the Middle Ages. He did this primarily through a question-and-answer format, which was common when he was writing (what historians call the scholastic period).
What Does a Typical Chapter of Summa Theologica Look Like?
He did this primarily through a question-and-answer format, which was common when he was writing (what historians call the scholastic period).
The question-and-answer format starts with one to three false assertions about the topic. Then Aquinas quotes an authority (most commonly Aristotle or Augustine). Finally, he makes a rigorous argument that his assertion is true. Finally, he responds to the objections and refutes them.
Here is a sample article from Part I Question 2 Article 2, addressing “Whether it can be demonstrated that God exists?”
“Objection 1: It seems that the existence of God cannot be demonstrated. For it is an article of faith that God exists. But what is of faith cannot be demonstrated because a demonstration produces scientific knowledge.
Objection 2: Further, the essence is the middle term of demonstration. But we cannot know in what God’s essence consists, but solely in what it does not consist; as Damascene says (De Fide Orth. i, 4). Therefore we cannot demonstrate that God exists.
Objection 3: Further, if the existence of God were demonstrated, this could only be from His effects. But His effects are not proportionate to Him, since He is infinite and His effects are finite; and between the finite and infinite there is no proportion. Therefore, since a cause cannot be demonstrated by an effect not proportionate to it, it seems that the existence of God cannot be demonstrated.
On the contrary, The Apostle (Paul) says: ‘The invisible things of Him are clearly seen, being understood by the things that are made’ (Rom. 1:20). But this would not be unless the existence of God could be demonstrated through the things that are made; for the first thing we must know of anything is whether it exists.
I answer that, Demonstration can be made in two ways: One is through the cause, and is called ‘a priori,’ and this is to argue from what is prior absolutely. The other is through the effect, and is called a demonstration ‘a posteriori’; this is to argue from what is prior relatively only to us. When an effect is better known to us than its cause, from the effect we proceed to the knowledge of the cause. And from every effect the existence of its proper cause can be demonstrated, so long as its effects are better known to us; because since every effect depends upon its cause, if the effect exists, the cause must pre-exist. Hence the existence of God, in so far as it is not self-evident to us, can be demonstrated from those of His effects which are known to us.
Reply to Objection 1: The existence of God and other like truths about God, which can be known by natural reason, are not articles of faith, but are preambles to the articles; for faith presupposes natural knowledge, even as grace presupposes nature, and perfection supposes something that can be perfected. Nevertheless, there is nothing to prevent a man, who cannot grasp a proof, accepting, as a matter of faith, something which in itself is capable of being scientifically known and demonstrated.
Reply to Objection 2: When the existence of a cause is demonstrated from an effect, this effect takes the place of the definition of the cause in proof of the cause’s existence. This is especially the case in regard to God, because, in order to prove the existence of anything, it is necessary to accept as a middle term the meaning of the word, and not its essence, for the question of its essence follows on the question of its existence. Now the names given to God are derived from His effects; consequently, in demonstrating the existence of God from His effects, we may take for the middle term the meaning of the word ‘God.’
Reply to Objection 3: From effects not proportionate to the cause no perfect knowledge of that cause can be obtained. Yet from every effect the existence of the cause can be clearly demonstrated, and so we can demonstrate the existence of God from His effects; though from them we cannot perfectly know God as He is in His essence.”
This is a shorter article by Aquinas. There are 512 articles like this throughout the work.
While the systematic moving through ideas takes some getting used to, Summa Theologica’s philosophical rigor comes across well in this quote. It also addresses a topic that is quite relevant today, when many people argue it cannot be demonstrated whether or not God exists.
What is the Structure of Summa Theologica?
Thomas’ topics go in a cyclical fashion, from God to Creation to man, to Christ, to the sacraments, and back to God.
The focus shows Thomas’ focus on the Sacraments as instrumental to God’s plan of redemption. This is clear in sections like Part III Question 61 Article 4, where he describes the sacraments as crucial for salvation” because Christ confers grace through them.
What Does Summa Theologica Say about God?
Aquinas’ main point on God in Part I regards his simplicity. Divine simplicity is the idea that God is not divisible into parts. For example, God does not contain life but is life itself. According to Aquinas, “God is a being without parts, without composition, without diversity, without division, without extension, without motion, without change, without succession, without temporal before and after, and without time. Therefore, He is a simple being.”
Aquinas goes into more depth about how the members of the Trinity than any theologian before or since. Part I Questions 27-43 all deal with the nature of the Trinity. His main thesis is that because God is one but three, the Father eternally generates the Son, and the Spirit eternally proceeds from the Father and the Son. Generation does not mean a separate creation (which would fit into the heresy of Arianism).
What Does Summa Theologica Say about Jesus?
Aquinas gives a thorough treatment of both humanity and divinity—also called the hypostatic union. In fact, he gives an unparalleled defense of this orthodox doctrine that Jesus was both God and man.
In those sections, Aquinas not only defends orthodox ideas but also challenges a wide variety of heresies about the nature of Jesus.
Part III Questions 1-26 all deal with the nature of Jesus’ incarnation and address many of the church’s heresies about Jesus’ humanity and divinity. This section aids us as believers today because it addresses many problematic beliefs people have about God.
How Did Summa Theologica Help Develop Future Roman Catholic Doctrine?
Aquinas admits that the view of Mary is not backed up by scripture, and so he relies on the other two legs—Catholic Dogma and Tradition, and the Pope. You can see how he pursues that line of reasoning in Part III Section 27.
Thomas Aquinas’ views on the sacraments are decidedly Roman Catholic. He believes they are the main way to receive Grace from God. Protestants, meanwhile, believe that we have been given all the grace we will ever need through Jesus’s death on the cross, and that sacraments remind us of Jesus’s sacrifice and bring us closer to him by remembering him. Aquinas, meanwhile, holds that the sacraments are necessary for salvation because they are the means by which grace is distributed to the believer.
What Can Protestants Today Learn From Summa Theologica?
There is a significant difference in authority between Roman Catholics and Protestants. For one thing, Catholics hold Church tradition on the same level as scripture. This was also the case for Aquinas, who held that Mary was sinless in her life because it fit Catholic tradition—and he felt it was necessary to preserve Jesus’ integrity.
This point is one area that makes the Catholic doctrine of Mary so difficult for Protestants. As mentioned above, he acknowledges that none of these doctrines about Mary are supported in scripture. However, it’s worth noting that even early reformers like Calvin and Luther believed that Mary was a virgin throughout her entire life, since the teaching was integral to their church upbringing.
The key distinctive where the sacraments are concerned is the idea of the imputed righteousness of Christ. To Protestants, Christ’s grace is given fully when we believe in him. The sacraments, then, make us aware of the reality that has already taken place on our behalf, that when God looks at us, he sees Jesus. This contrasts with the Catholic doctrine that the sacraments infuse God’s grace into our lives.
Aquinas’ defense of divine simplicity and God’s interaction within the Trinity is also incredibly helpful for us today. The Summa gives many great insights into a proper theology of the interaction between members of the Trinity. His philosophical rigor made him a valuable resource for the Protestant Church in future generations, despite his decidedly Roman Catholic views on Mary and the Sacraments.
One great example of the Summa’s influence appears in the theology of seventeenth-century reformed scholars, known as Reformed Scholasticism. These people attempted to use Aquinas’ methodology to support their Calvinist theology.
How Should I Read Summa Theologica?
The entire work is available in several translations. One very accessible, public-domain translation was made in 1911 by the Fathers of the English Dominican Province. It can be read for free on Christian Classics Ethereal Library (CCEL). Oxford University Press has a guide on other translations for different uses—less literal translations, translations with study guides, and so on.
While Summa Theological is an incredibly valuable work on who God is, that does not make it light reading. Reading the work cover to cover is a large and overwhelming undertaking. Many seminary students may find it is too long to read and study the entire book during their few years of study while juggling other responsibilities. For most readers, it’s best treated as a reference book. Those who want to study it will likely have to consider sections over time without worrying about trying to finish it in a year.
Dan Graves’ Bibliography:
1. “Aquinas, St. Thomas.” Dictionary of Scientific Biography. Editor Charles Coulston Gillispie. New York: Scribner’s, 1970.
2. Chesterton, G.K. Saint Thomas Aquinas; the Dumb Ox. Garden City, New York: Doubleday Image Books, 1956.
3. Guillen, Michael. Bridges to Infinity; the human side of mathematics. Los Angeles: Tarcher, 1983.
4. Kennedy, D.J. “St. Thomas Aquinas.” The Catholic Encyclopedia. New York: Robert Appleton, 1914.
5. McKeon, Richard. Selections from Medieval Philosophers II. Roger Bacon to William of Ockham. New York: Scribners, 1930. p. 149.
6. Morris, Clarence. Great Legal Philosophers. Philadelphia: University of Pennsylvania, 1959.
7. Runes, Dagobert D. A Treasury of Philosophy. New York: Philosophical Library, 1945.
8. Russell, Bertrand. Wisdom of the West. New York: Fawcett, 1964.
9. Sproul, R.C. “Thomas Aquinas.” Chosen Vessels: portraits of ten outstanding Christian men; edited by Charles Turner. Ann Arbor, Michigan: Vine Books, 1985.
10. Thomas Aquinas. Christian History Magazine, #73.
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Ben Reichert works with college students in New Zealand. He graduated from Iowa State in 2019 with degrees in Bioinformatics and Computational Biology, and agronomy. He is passionate about church history, theology, and having people walk with Jesus. When not working or writing you can find him running or hiking in the beautiful New Zealand Bush.
