Aquinas on the Filioque
Summa Reading Group
Join a Summa Reading Group with Fr. John Baptist Ku, O.P.
Saturdays, May 2nd - 23rd, from 2:00-3:00 PM ET on ZOOM
Open to TI Alumni
THE APPLICATION DEADLINE IS APRIL 23, 2026!
This course will examine the question of the Holy Spirit’s procession from the Son in St. Thomas Aquinas’s Summa Theologiae, q. 36, aa. 2-4 over four class meetings. The first class will briefly review the history of the controversy over the introduction of the Filioque into the Niceno-Constantinopolitan Creed by the Latin liturgy as well as examine key texts of the Fathers of the Church and Church councils. Then, turning to the Summa, the subsequent classes will investigate Aquinas’s consideration of whether the Holy Spirit proceeds from the Son, whether the Holy Spirit proceeds through the Son, and whether the Father and the Son are one single principle of the Holy Spirit.
Reading from Scripture:
Mt 4:4; Mk 7:15–20; Jn 15:26; Acts 9:28; Rev 9:17–18; Rev 22:1
Selections from Church Fathers:
Origen, Commentary on John, bk. 2, ch. 10, sect. 75
Athanasius, Epistola ad Serapionem I.20, I.21
Basil of Caesarea, De Spiritu Sancto, ch. 17, sect. 43 (col. 1, -12)
Gregory of Nazianzus, Oration 39.12.
Gregory of Nazianzus, On Pentecost, Oration 41.9.
Gregory of Nyssa, Against Eunomius 1.42.
Cyril of Alexandria, Thesaurus de sancta et consubstantiali trinitate 34.
Maximus the Confessor, Quaestiones ad Thalassium 63.
John Damascene, De Fide Orthodoxa 1.8
Tertullian, Adversus Praxeam, ch. 8, line 42.
Pope Leo I, Quam laudabiliter
Augustine, De Trinitate, bk. 15, ch. 17, no. 29
Reading from Church Doctrine:
Council of Lyons II
Council of Florence, Session 6—6 July 1439
CCC §247
Reading from Aquinas:
ST Ia, q.36 a.2 - Whether the Holy Spirit proceeds from the Son?
ST Ia, q. 36 a.3 - Whether the Holy Spirit proceeds from the Father through the Son?
ST Ia q.33, a.1 - Whether it belongs to the Father to be the principle of the Son or of the Holy Spirit?
ST Ia q.36, a.4 - Whether the Father and the Son are one principle of the Holy Spirit?
De Potentia q.10, a.5, ad.10 - Whether the Holy Spirit would still be distinct from the Son if he did not proceed from him
Apply below!
