The Great Tradition

Augustine, Aquinas, and Christian Thought

Christianity is not only a religion of the heart — it is one of the great intellectual traditions of human civilization. In this lesson, you will meet two towering minds: Augustine, who asked what it means to live in a world that is both beautiful and broken; and Thomas Aquinas, who tried to prove that faith and reason are not enemies but allies. You will also encounter the mystical tradition — Christians who sought direct experience of God.

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Augustine of Hippo: The Man Who Shaped Christianity

Video ~10 min

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A compelling introduction to Augustine — his wild youth, dramatic conversion, and the theological ideas (original sin, grace, the City of God) that shaped Western Christianity for 1,500 years.

Channel: Ryan Reeves

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Faith Seeking Understanding

Reading ~5 min

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Christianity has always had a complex relationship with the life of the mind. Jesus was not a philosopher. Paul warned against 'the wisdom of this world.' And yet, within centuries, Christian thinkers produced some of the most sophisticated philosophy in human history.

Augustine of Hippo (354-430 CE) is the most influential Christian thinker after Paul. A brilliant North African rhetorician who converted to Christianity after years of searching, Augustine asked the deepest questions: What is time? What is evil? Why does the human will pull in two directions at once?

His Confessions opens with one of the most famous lines in all of literature: 'You have made us for yourself, O Lord, and our hearts are restless until they rest in you.'

His City of God — written after the sack of Rome in 410 CE — argues that human history is a drama played out between two 'cities': the City of God (those who love God) and the City of Man (those who love themselves). This framework shaped Western political thought for a millennium.

Thomas Aquinas (1225-1274) is Christianity's greatest systematic thinker. His Summa Theologica is an encyclopedic attempt to reconcile faith and reason, showing that the truths of Christianity are not contrary to philosophy but complete it.

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Augustine: The Two Cities

Primary Source ~8 min

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St. Augustine's City of God and Christian Doctrine — Saint Augustine of Hippo

Open in Ocean Library ↗

But in order to your acquiescence in this truth, it is lowliness that is requisite, and to this it is extremely difficult to bend you. For what is there incredible, especially to men like you, accustomed to speculation, which might have predisposed you to believe in this, — what is there incredible, I say, in the assertion that God assumed a human soul and body?

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Teacher's note

In this passage from The City of God, Augustine addresses pagan philosophers directly. He argues that the Incarnation — God becoming human — should not be incredible to those who already believe in the soul's connection to the divine. Augustine's genius is in meeting non-Christians on their own philosophical ground, showing that Christianity answers questions they were already asking.

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The Mystical Tradition

Reading ~5 min

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Alongside the intellectual tradition, Christianity has always had a mystical stream — seekers who wanted not just to think about God but to experience God directly.

The mystical tradition includes:

- The Desert Fathers and Mothers (3rd-4th centuries) — hermits who withdrew to the Egyptian desert to pursue radical simplicity and prayer - Meister Eckhart (c. 1260-1328) — a German Dominican whose sermons on the 'God beyond God' anticipate modern theology - Julian of Norwich (1342-1416) — an English mystic whose Revelations of Divine Love is the first book in English known to be written by a woman - Teresa of Ávila (1515-1582) — a Spanish Carmelite whose Interior Castle maps the soul's journey toward God - Thomas Merton (1915-1968) — a Trappist monk whose writings on contemplation and social justice bridge Christianity and Buddhism

What unites these figures is the conviction that God is not just an idea to be believed but a presence to be encountered — in silence, in suffering, in the depths of the self.

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Jonathan Edwards: The Nature of True Religion

Primary Source ~8 min

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Religious Affections — Jonathan Edwards

Open in Ocean Library ↗

The evidence of this in the Scripture is very abundant. If we judge of the Nature of Christianity, and the proper spirit of the gospel, by the word of God, this spirit is what may, by way of eminency, be called the Christian spirit; and may be looked upon as the true, and distinguishing disposition of the hearts of Christians as Christians.

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Teacher's note

Jonathan Edwards (1703-1758) was America's greatest theologian. In Religious Affections, he asks: what distinguishes genuine faith from mere enthusiasm? His answer: true religion transforms the heart — not just beliefs but desires, emotions, and the direction of the whole person. Edwards bridges the intellectual and mystical traditions, insisting that both head and heart must be engaged.

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Thomas Aquinas and the Summa Theologica

Video ~10 min

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An introduction to Thomas Aquinas — his five proofs for God's existence, his synthesis of Aristotle and Christianity, and why the Summa Theologica is considered the greatest work of medieval philosophy.

Channel: Ryan Reeves

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Key Terms: Christian Thought and Mysticism

Key Terms ~3 min

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Who was Augustine of Hippo? tap to reveal

The most influential Christian thinker after Paul (354-430 CE). His Confessions and City of God shaped Western theology, philosophy, and political thought for 1,500 years.

What is the City of God? tap to reveal

Augustine's masterwork — argues that history is a drama between two 'cities': those who love God (City of God) and those who love themselves (City of Man).

Who was Thomas Aquinas? tap to reveal

Christianity's greatest systematic thinker (1225-1274). His Summa Theologica reconciles faith and reason, showing that philosophy and theology are complementary.

What is the Incarnation? tap to reveal

The central Christian doctrine that God became human in Jesus Christ — the divine Word 'became flesh and dwelt among us' (John 1:14).

What is Christian Mysticism? tap to reveal

The tradition of seeking direct experience of God — through prayer, contemplation, silence, and self-surrender. Major figures include Meister Eckhart, Julian of Norwich, and Teresa of Ávila.

Who was Jonathan Edwards? tap to reveal

America's greatest theologian (1703-1758). His Religious Affections argues that true faith transforms the whole person — beliefs, desires, emotions, and actions.

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Check Your Understanding

Comprehension Check ~5 min

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1. What is Augustine's central argument in The City of God?

Christians should build a literal city for God

History is a drama between those who love God and those who love themselves — two 'cities' coexisting in the world

All earthly governments are inherently evil

The Roman Empire was God's chosen kingdom

2. What is the relationship between faith and reason in Aquinas's thought?

Reason is evil and must be abandoned for faith

Aquinas rejected all Greek philosophy

Faith is for simple people; educated people need only reason

They are allies — reason can demonstrate truths that faith completes, and they never truly contradict

3. What distinguishes Christian mysticism from Christian theology?

Theology is always opposed to mystical experience

Mysticism is a modern invention

Mystics reject all Christian doctrine

Mystics seek direct experience of God through prayer and contemplation, not just intellectual understanding

4. What does Edwards mean by 'religious affections'?

The deep movements of the heart that characterize genuine faith — transformed desires and emotions, not just beliefs

Physical sensations during prayer

Being emotionally attached to religious buildings

Feeling happy during church services

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Reflection: Restless Hearts

Essay Prompt ~15 min

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Augustine wrote: 'You have made us for yourself, O Lord, and our hearts are restless until they rest in you.' This is a claim about human nature — that there is a fundamental restlessness built into the human condition, and that it can only be satisfied by something beyond ourselves. Do you experience this kind of restlessness? Is it spiritual, or could it be explained differently (psychology, biology, social conditioning)? What do you think humans are ultimately searching for — and can it be found?