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Summa Theologica by Thomas Aquinas — book cover
Anthropology · Attributes · Catholic Church

Summa Theologica by Thomas Aquinas — Summary, Key Ideas & Quotes

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What is Summa Theologica about?

Thomas's magnum opus, comprising a systematic integration of Aristotelian philosophy with Christianity. Covers topics such as the nature and existence of God, human nature, law and morality and the relationship of God, world and humans.

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Illustration for Summa Theologica
The Harmony of Faith and Reason

Aquinas argues that faith and reason are not opposed but complementary. He believes that truths revealed by God (faith) and those discovered by human intellect (reason) ultimately align, since both originate from the same divine source. This idea underpins his method: using rational argumentation to clarify and defend theological doctrines, making the case that philosophy and theology can and should inform each other.

The Existence and Nature of God

One of the most famous sections presents Aquinas’s ‘Five Ways’—philosophical arguments for the existence of God based on observation of the natural world. He also explores God’s attributes, such as simplicity, omnipotence, and goodness, emphasizing that while we can know God exists and certain things about Him, the divine essence ultimately transcends human understanding.

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Get smart in 3 min
6 key ideas, distilled
›
  1. 1The Harmony of Faith and Reason
  2. 2The Existence and Nature of God
  3. 3Human Nature and the Soul
  4. 4Natural Law and Morality
  5. 5Theological Virtues and the Path to Happiness

Popular quotes from Summa Theologica

“To one who has faith, no explanation is necessary. To one without faith, no explanation is possible.”
“The things that we love tell us what we are.”
“Wonder is the desire for knowledge.”

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Thomas's magnum opus, comprising a systematic integration of Aristotelian philosophy with Christianity. Covers topics such as the nature and existence of God, human nature, law and morality and the relationship of God, world and humans.