Catholic Treasury Network
Catholic Theology · For seminarians, teachers, and the curious

Why does the Church teach this?

The questions Catholics get asked — and the answers as the great seminary manuals explain them. Pohle-Preuss as the spine, Glenn's Tour of the Summa as your bridge to Aquinas, and the major encyclicals in context.

Common questions

Each question opens the tract where Pohle-Preuss treats it in full.

psychology Does God exist? How can we know? arrow_forward all_inclusive Why do Catholics believe in the Trinity? arrow_forward church What did Christ accomplish on the Cross? arrow_forward star Why pray to Mary? Why honour the saints? arrow_forward wb_sunny How does grace actually work in the soul? arrow_forward celebration What really happens at Mass? arrow_forward balance How does the Church teach about morality? arrow_forward account_balance Why is there a Pope? arrow_forward hourglass_empty What happens after we die? arrow_forward

The twelve tracts

The traditional division of Catholic dogmatic theology — each one mapped to a Pohle-Preuss volume and the relevant questions of the Summa.

Tract I
God: Existence & Attributes
Pohle Vol. I · Summa I, QQ. 2–26

God's knowability, existence demonstrated by reason, essence and attributes.

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Tract II
The Blessed Trinity
Pohle Vol. II · Summa I, QQ. 27–43

The divine processions, relations, and persons.

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Tract III
Creation & the Supernatural Order
Pohle Vol. III · Summa I, QQ. 44–119

God as Creator, angels, man, original justice and original sin.

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Tract IV
Christology
Pohle Vol. IV · Summa III, QQ. 1–26

The Incarnation, the hypostatic union, the two natures of Christ.

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Tract V
Soteriology
Pohle Vol. V · Summa III, QQ. 46–52

The Redemption, Christ's passion, satisfaction and merit.

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Tract VI
Mariology
Pohle Vol. VI

Divine motherhood, perpetual virginity, Immaculate Conception, Assumption.

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Tract VII
Grace
Pohle Vol. VII · Summa I-II, QQ. 109–114

Actual and habitual grace, justification, merit.

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Tract VIII
The Sacraments
Pohle Vols. VIII–XI · Summa III, QQ. 60–90

The seven sacraments in general and in particular.

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Tract IX
Moral Theology
Summa I-II & II-II

Conscience, law, sin, the virtues and vices, the Commandments.

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Tract X
Ecclesiology
Wilhelm-Scannell Vol. 2

The Church, papal primacy and infallibility, development of doctrine.

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Tract XI
Eschatology
Pohle Vol. XII · Summa Suppl., QQ. 69–99

Death, particular judgement, heaven, hell, purgatory, the resurrection.

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Tract XII
Spiritual Theology
See Treasury Library

The purgative, illuminative, and unitive ways; prayer; perfection.

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Featured magisterial documents

Encyclicals and conciliar documents that shaped how the Church teaches each tract. Each précis is one screen — read in five minutes, link to the full Vatican text.

Benedictus Deus
Benedict XII · 1336

Defines as dogma that the souls of the just enjoy the beatific vision immediately after death (or after purgation), and that the damned descend to hell immediately — settling the controversy over the interim state of souls before the General Judgement.

Dei Filius
Vatican Council I · 1870

Defines the Catholic doctrine on God the Creator, on divine revelation, on faith and reason, and on the relationship between faith and science — establishing the dogmatic foundations that all subsequent theology presupposes.

Pastor Aeternus
Vatican Council I · 1870

Defines the dogma of papal primacy of jurisdiction over the universal Church and papal infallibility when the Pope speaks ex cathedra on matters of faith and morals.

Aeterni Patris
Leo XIII · 1879

Restores the philosophy and theology of St Thomas Aquinas as the Church's authoritative intellectual method — inaugurating the Thomistic revival within which Pohle, Tanquerey, and the entire modern manual tradition write.

Rerum Novarum
Leo XIII · 1891

The founding document of Catholic social teaching — addressing the condition of workers, the right to private property, the just wage, and the proper roles of the state, the Church, and voluntary associations.

Mystici Corporis Christi
Pius XII · 1943

Defines the Church as the Mystical Body of Christ — a visible, hierarchical society animated by the Holy Spirit and governed by the Pope as Vicar of Christ.

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New to Catholic theology?

A clear path for a complete beginner.

  1. Start with the Penny Catechism on Catholic Treasury — the answers in their simplest form.
  2. Read Glenn's Tour: Q.2 — The Existence of God — Aquinas's Five Ways made accessible.
  3. Explore the Grace tract — the most complete on the site, with all 23 of Pohle's chapters.
  4. Dei Filius on the relationship of faith and reason — short, definitive, and clarifying.
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"Theology is taught by God, teaches of God, and leads to God."
— St Thomas Aquinas, Summa Theologica I, Prologue