Steve Stanley’s Reviews > 40 Questions About the Trinity > Status Update

In his [Aquinas's] scholastic treatment of the doctrine, there is one essence (the shared divine nature), two processions (eternal generation and eternal spiration), three persons (Father, Son, and Spirit), four relations (paternity, filiation, joint spiriation, and procession), and five notions (innascibility, paternity, filiation, joint spiriation, and procession).

[According to Aquinas, there are] five notions: innascibility and paternity (by which we know the Father), filiation (by which we know the Son), spiration (by which we know the Father and Son jointly), and procession (by which we know the Holy Spirit).

At the risk of being cheeky, we can summarize Thomas's Trinitarian contribution by counting to five: one essence, two processions, three persons, four relations, five notions.

The scriptural names for the persons faithfully communicate who they are. The Son is from the Father. The Spirit comes forth from the Father. These relations of origin secure at once the substantial equality and the personal distinctions of the three persons.

The three [persons] are distinguished not by substance, by will, or by role. They are distinguished only by relation. The Son is begotten from and the Holy Spirit proceeds from the unbegotten Father.

There is only one action in creation, redemption, or any other divine operation, but each divine person participates in that indivisible action according to his personal mode of subsistence [thus the doctrine of inseparable operations]. God's actions proceed from the Father, through the Son, and in the Holy Spirit.

Since God is one, God acts as one. The doctrine of inseparable operations—that all of God's external actions are carried out indivisibly by all three divine persons—is often associated with Augustine, who gives it its classic formulation.

As the Son is eternally *begotten* from the Father, so also the Spirit eternally *proceeds* from the Father ... The Comforter is sent from the Father because he eternally proceeds from the Father, that is, he eternally *comes forth* from the Father. This relation of origin is distinguished from the eternal begetting of the Son, but it likewise marks out both sameness of essence and distinction of relation.

The personal names for the divine persons given in the biblical revelation, Father and Son, mark out their eternal relations of origin. The Father is unbegotten, and the Son is eternally begotten of the Father. . . . This relation marks out both sameness of essence (because the one begotten is of the same nature as the begetter), and the distinction (the Son eternally has this selfsame essence *from* the Father).