Catholic Equivalent of Systematic Theology Books I am looking for the “textbook” that catholic priests use when they are learning to become priests. A comprehensive book that covers everything Something like the systematic theology books that protestants study from in seminary. 

Are there any catholic priests that can share what textbook they used? (Other than the bible of course)

Thank you.
St. Thomas Aquinas's Summa Theologica
The Summa Theologica* of St. Thomas Aquinas (✝1274) is the best &quot;systematic theology†&quot; work, as it summarizes and consolidates  all theology (sacra doctrina, &quot;sacred doctrine&quot;) into a coherent whole. The Summa, rejected by Luther and Calvin, has great authority for Catholics and was placed on the altar alongside Holy Scriptures at the Council of Trent. Every pope since St. Thomas's time has endorsed his work, and even today Canon Law (can. 252 §3) requires that seminarians “are to learn to penetrate more intimately the mysteries of salvation, especially with St. Thomas as a teacher.” (cf. 1917 can. 1366 §2).
*cf. Thom's answer here†&quot;Systematic theology&quot; (theologia systematica) was coined c. 1635; Catholics use the term &quot;dogmatic theology.&quot;
Here are some testimonies of the Summa:

St. Robert Bellarmine similarly speaks of St. Thomas in the introduction of his treatise on the Holy Trinity:

Certainly, if everyone proposes with such order, facility, and brevity to us, as I venture to affirm, that he who diligently studies a few of St. Thomas’s questions finds nothing difficult either in Scriptures, the Councils, or the future Fathers of the Trinity; he will make more all-around progress in two months devoted to the Summa than in several months’ study of the Scriptures and the Fathers.

Pope John XXII also said:

He (St. Thomas) has illuminated the Church more than all the other Doctors; to read his books for a year profits man more than to study the doctrine of others for his whole life.


Theological Manuals
Catholic seminarians use theological manuals based on St. Thomas Aquinas's Summa. Dozens have been published in the 20th century alone with titles like:

De Beatissima Virgine Maria Matre Dei (On the Holy Virgin Mary Mother of God)
De Deo Trino (On the Trinity)
De Deo Uno (On the One God)
De Ecclesia (On the Church)
De Gratia (On Grace)
De Peccato Originali (On Original Sin)
De Revelatione (On Revelation)
De Rubricis Missalis Romanis (On the Rubrics of the Roman Missal / liturgics)
De Sacramentis (On the Sacraments)
De Verbo Incarnato et Redemptore (On the Word Incarnate and Redeemer)
De Virtutibus (On the Virtues)
Jus Canonicum (Canon Law)
Theologia Ascetica et Mystica (Ascetical and Mystical Theology)
Theologia Moralis (Moral Theology)
Theologia Pastoralis (Pastoral Theology)

See the curriculum for this seminary. Many of its works are available online for download. Ludwig Ott's Fundemantals of Catholic Dogma and Pohle-Preuss's dogmatic theology series are some popular ones that have been translated into English.