Based on the Pontificator's list of "Essential Theological Books", here are my choices, in approximate chronological order:
1. The Didache
2. St. Ignatius (of Antioch), Letters
3. St. Athanasius, De Incarnatione
4. St. Augustine, De Civitate Dei
5. St. Gregory the Great, OSB, Sermons
6. St. Anselm, OSB, Cur Deus Homo
7. St. Thomas Aquinas, OP, Summa contra Gentiles
8. St. Thomas Aquinas, OP, Catena Aurea
9. St. Thomas Aquinas, OP, Comments on Aristotle (Metaphysics and Nicomachean Ethics)
10. St. Thomas Aquinas, OP, Summa Theologiæ
11. The Imitation of Christ
12. The Roman Catechism
13. St. Robert Bellarmine, SI, Exposition of Christian Doctrine
14. Francisco Suárez, SI, Disputationes Metaphysicæ
15. St. Teresa of Avila, OCD, Interior Castle
16. Jacques-Bénigne Bossuet, Discourse on Universal History
17. St. Louis-Marie Grignion de Montfort, Treaty of the True Devotion to the Blessed Virgin Mary
18. Henri-Dominique Lacordaire, OP, Conférences de Notre-Dame de Paris
19. Réginald Garrigou-Lagrange, OP, The Three Ages of Interior Life
20. Jacques Maritain, Théonas
One other very essential work should be added, in two editions: Heinrich Denzinger's "Enchiridion Symbolorum", in pre-Vatican II and in its current (Denzinger-Schönmetzer) versions.
1. The Didache
2. St. Ignatius (of Antioch), Letters
3. St. Athanasius, De Incarnatione
4. St. Augustine, De Civitate Dei
5. St. Gregory the Great, OSB, Sermons
6. St. Anselm, OSB, Cur Deus Homo
7. St. Thomas Aquinas, OP, Summa contra Gentiles
8. St. Thomas Aquinas, OP, Catena Aurea
9. St. Thomas Aquinas, OP, Comments on Aristotle (Metaphysics and Nicomachean Ethics)
10. St. Thomas Aquinas, OP, Summa Theologiæ
11. The Imitation of Christ
12. The Roman Catechism
13. St. Robert Bellarmine, SI, Exposition of Christian Doctrine
14. Francisco Suárez, SI, Disputationes Metaphysicæ
15. St. Teresa of Avila, OCD, Interior Castle
16. Jacques-Bénigne Bossuet, Discourse on Universal History
17. St. Louis-Marie Grignion de Montfort, Treaty of the True Devotion to the Blessed Virgin Mary
18. Henri-Dominique Lacordaire, OP, Conférences de Notre-Dame de Paris
19. Réginald Garrigou-Lagrange, OP, The Three Ages of Interior Life
20. Jacques Maritain, Théonas
One other very essential work should be added, in two editions: Heinrich Denzinger's "Enchiridion Symbolorum", in pre-Vatican II and in its current (Denzinger-Schönmetzer) versions.
