De Trinitate

On the Trinity (De Trinitate), composed over some quarter-century (c. 400–426), is Augustine’s most demanding work and the summit of Latin Trinitarian theology — fifteen books that defend the Nicene faith against Arian objections, work out the grammar of speaking about one God in three Persons, and then turn inward to seek images (vestigia) of the Trinity in the structure of the human mind made in God’s image. This file sets out Augustine’s Trinitarian theology on its own terms: the unity of the divine essence, the doctrine of relations, and the famous psychological analogies — before the next file takes up the contested question of the Filioque.

Tradition: Pan-Orthodox (pre-Schism West; “Blessed Augustine”)

The Work and Its Aim

Augustine began On the Trinity around 400 and worked at it, with interruptions, until about 426, releasing it only when an unfinished copy was circulated without his leave (Letter 174, the prefatory letter to Bishop Aurelius; Brown 2000, ch. 23). His aim was twofold: to defend the full and equal divinity of Father, Son, and Holy Spirit — the Nicene faith — against the lingering Arian and Eunomian objections that the Son and Spirit must be lesser than the Father; and to lead the believing mind toward some understanding (intellectus) of the mystery it confesses by faith, according to his governing principle “believe that you may understand” (crede ut intelligas) (On the Trinity 1.2; 15.2; trans. NPNF I/3). The first seven books are the doctrinal exposition; the last eight are the inward search for images of the Trinity in the soul.

The Unity of the Essence

Augustine’s Trinitarian theology begins from the unity of the divine essence (una essentia, una substantia). The three Persons are one God, one substance, equal and co-eternal, sharing a single, simple, indivisible divine nature; whatever is said of God’s nature — good, eternal, omnipotent — is said of the three together and of each, for there are not three eternals or three almighties but one (On the Trinity 1.4–7; 5.8; trans. NPNF I/3). The external works of the Trinity are undivided (opera Trinitatis ad extra indivisa sunt): in every act toward creation the three Persons work inseparably, though Scripture may appropriate a work especially to one of them (On the Trinity 1.4–5; 4.21). This stress on the one simple essence as the framework within which the three Persons are distinguished is characteristically Augustinian, and it is often contrasted with the more characteristically Greek (Cappadocian) starting point from the three Persons and the Father as their source [Disputed: the older "De Régnon paradigm" — named for Théodore de Régnon (1892) — held that Latin Trinitarian theology (Augustine) characteristically begins from the one divine essence and Greek theology from the three Persons/the *monarchia* of the Father, a contrast later used to set Augustine against the Cappadocians; recent scholarship (Lewis Ayres, Michel Barnes, and contributors to *Orthodox Readings of Augustine*) has substantially criticized this paradigm as an over-schematized nineteenth-century construct, arguing that Augustine too gives full weight to the Persons and stands closer to Nicene pro-Nicene theology, Greek and Latin alike, than the paradigm allows. The contrast is therefore real in tendency but contested as a sharp opposition.].

The Doctrine of Relations

How are the three distinguished, if the essence is one and simple? Augustine answers, developing a line from the Cappadocians and from Latin tradition, that the Persons are distinguished not by anything in the essence (which is common) nor by accidents (for God has none) but by their relations of origin — the eternal relations of Father, Son, and Spirit to one another (On the Trinity 5.5–6; trans. NPNF I/3). The Father is Father in relation to the Son; the Son is Son in relation to the Father; what distinguishes the Persons is precisely their mutual relations (relatio), not their substance. This doctrine of subsistent relations — that the divine Persons are distinguished relationally while remaining one in essence — became foundational for all later Western Trinitarian theology and was taken up and refined by Thomas Aquinas. It is also, as the next file shows, the conceptual matrix within which Augustine framed the procession of the Spirit in a way the later Latin Filioque would invoke.

The Holy Spirit as Love and Gift

Augustine gives a distinctive account of the Holy Spirit. Drawing on Romans 5:5 (“the love of God has been poured into our hearts through the Holy Spirit”), he names the Spirit especially as Love (Caritas) and as Gift (Donum) — the mutual love of the Father and the Son, the bond (communio, vinculum) of their unity, who proceeds from both as their common love (On the Trinity 6.5; 15.17–19; trans. NPNF I/3). “The Holy Spirit… is a certain unutterable communion of the Father and the Son,” he writes, “the Spirit of both” (On the Trinity 5.11; 15.17). This identification of the Spirit as the mutual Love and Gift binding Father and Son is among Augustine’s most original and beautiful contributions — and it is also precisely where his theology touches the Filioque, since to call the Spirit the mutual love of the Father and Son is to imply a procession from both (see Augustine and the Filioque).

The Psychological Analogies

The last and most famous part of On the Trinity (Books 8–15) is Augustine’s inward search for an image of the Trinity in the human mind, which Scripture says is made in God’s image (Genesis 1:26–27). If man is made in the image of the triune God, Augustine reasons, then some trace (vestigium) of the Trinity should be discoverable in the highest part of man, the rational mind (mens) (On the Trinity 9.2; 15.3; trans. NPNF I/3). He proposes a series of mental triads, each a unity-in-threeness:

the lover, the beloved, and the love that joins them (amans, quod amatur, amor) (On the Trinity 8.10; 9.2);
the mind, its knowledge of itself, and its love of itself (mens, notitia, amor) (On the Trinity 9.3–5);
and, the most influential, the triad of memory, understanding, and will (memoria, intelligentia, voluntas) — the mind’s remembering, knowing, and loving of God, three faculties that are each the whole mind and yet distinct, one substance in three (On the Trinity 10.11–12; 14.8; trans. NPNF I/3).

These analogies are not, for Augustine, proofs of the Trinity nor adequate descriptions of it — he insists repeatedly on the infinite disproportion between the image and its archetype, and the work ends in a long confession of the inadequacy of all his words before the incomprehensible mystery and a prayer (On the Trinity 15.27–28, 15.50–51). They are aids to contemplation: the soul, finding the trace of the Trinity within itself, is led to remember, understand, and love the God in whose image it is made, and so to be reformed toward Him.

The psychological analogies are Augustine’s most celebrated and most criticized Trinitarian legacy. They shaped the whole subsequent Western “psychological” approach to the Trinity. The Eastern tradition, which prefers to begin from the three Persons revealed in the economy of salvation and is wary of seeking the Trinity by introspective analogy in the individual mind, has often regarded the psychological analogies as the seed of a Trinitarianism too philosophical and too centered on the unity of essence — a criticism that connects to the larger question of the Filioque [Disputed: the value of the psychological analogies is assessed differently. Critics in the Eastern tradition (and some Western theologians) hold that grounding the Trinity in the structure of the individual mind tends toward modalism and toward subordinating the three Persons to the one essence, and that it overphilosophizes a mystery known only in the economy; defenders (including recent revisionist scholars such as Ayres and contributors to *Orthodox Readings of Augustine*) hold that Augustine offered the analogies precisely as inadequate aids to contemplation, hedged them with repeated disclaimers, and remained firmly within Nicene orthodoxy. The disclaimers are in the text; the later use and misuse are part of the reception.].

A Work of Nicene Faith

Whatever the later disputes, On the Trinity must be read first as what it is: a profound defense of the Nicene confession of one God in three co-equal, co-eternal Persons, by a Father who labored for a quarter-century to lead the mind toward the mystery it adores and ended on his knees. Augustine’s Trinitarian theology is not, in itself, condemned by the East; he confesses the same Nicene faith. The contested point is narrower and sharper — the procession of the Holy Spirit, and the Filioque that the later West built, in part, upon his words. To that the next file turns.

References

Augustine of Hippo. On the Holy Trinity. Nicene and Post-Nicene Fathers, First Series, Vol. 3. 1887. (Unity of essence at 1.4–7; relations at 5.5–6; the Spirit as Love and Gift at 5.11, 6.5, 15.17–19; the psychological analogies at 8.10, 9.2–5, 10.11–12, 14.8; the closing confession at 15.27–28, 15.50–51.)
Ayres, Lewis. Augustine and the Trinity. Cambridge: Cambridge University Press, 2010.
Barnes, Michel René. “Augustine in Contemporary Trinitarian Theology.” Theological Studies 56 (1995).
Demacopoulos, George E., and Aristotle Papanikolaou, eds. Orthodox Readings of Augustine. Crestwood, NY: St Vladimir’s Seminary Press, 2008. (Critique of the De Régnon paradigm.)
Brown, Peter. Augustine of Hippo: A Biography. New ed. Berkeley: University of California Press, 2000. (Ch. 23.)