But the Greatest of these is Love: How Aquinas illuminates the person and work of the Holy Spirit

This article originated as a theology paper written as part of my studies with Union Theological College in Spring 2025.

‘So now faith, hope, and love abide, these three; but the greatest of these is love.’ These famous words from 1 Corinthians 13:13 demonstrate the importance of love in the theology of Paul. However, a similar statement could also be made about the pneumatology of Thomas Aquinas. Throughout his works, Aquinas repeatedly assigns three names to the third divine person: Holy Spirit, Gift, and Love.[1] Further, like Paul, he also argues that the greatest of these is Love, or more fully ‘God proceeding by way of love.’[2] This assignment examines the extent to which this description illuminates the person and work of the Holy Spirit. It argues Aquinas is right to set ‘love proceeding’ at the centre of his pneumatology. This is because it sheds light on important aspects of the Spirit’s person and work, and flows from how Scripture speaks of the same. This assignment begins by clarify what is meant by love proceeding. It then demonstrates how this description illuminates the Holy Spirit’s person and work respectively. In relation to his person, it argues that it illuminates the Spirit’s (1) divine person and (2) eternal relations. With respect to his work, it shows how love proceeding explains the Spirit’s work relating to (1) Christ, (2) creation and (3) Christians. It concludes by stressing the importance of the Holy Spirit being described as love proceeding, given the extent of its explanatory power.

The Name of the Holy Spirit

Aquinas begins his pneumatology by examining the names given to the third divine person.[3] This has been a fruitful task for many throughout history. For example, Gregory of Nazianzus also sought to investigate ‘the wealth of titles, the mass of names’ ascribed to the Holy Spirit.[4] By the thirteenth century, the medieval Augustinian tradition, as developed by Peter Lombard, primarily focused on three specific names: Holy Spirit, Love and Gift.[5] Aquinas gives attention to all three, devoting a question to each in Summa Theologica.[6] Nevertheless, of these names, Love is his theoretical centre and carries the greatest theological weight.[7] Some reject this, arguing that the New Testament more regularly associates truth with the Holy Spirit than love.[8] Further, Aquinas himself accepts that there is a danger of misunderstanding, as some have argued that the Spirit as love is an ‘accidental perfection bestowed by God on our souls.’[9] In contrast, Aquinas believes the love of God to be both essential and personal. Taken essentially, it refers to the attribute of love all three divine persons share. However, understood personally, it refers to the third person alone. Aquinas draws this conclusion from a modified form of Aristotelian anthropology.[10] Like Augustine, he relies on a likeness between the Trinty and the human mind (Gen. 1:26).[11] He asserts there is a human trinity in, ‘the mind itself in its natural existence; the conception of the mind in the intellect; and the mind loved in the will.’[12] While Aquinas accepts limitations to this analogy, given a human trinity is not of one nature, and each is only part of man’s subsistence, he believes it still illuminates the divine Trinity.[13] Aquinas supports this psychological analogy by noting how John explicitly applies it to the Son as the Word (John 1:1; 1 John 1:1).[14] It is on this basis that he concludes ‘besides the procession of the Word in God, there exists in Him another procession called the procession of love.’[15]

It is important that we understand what Aquinas means by this description. For he admits love can be understood in different ways, showing ‘the poverty of our vocabulary.’[16] Nevertheless, this should not stop us using the term, for many of these same misunderstandings are also possible with respect to the name of Word.[17] The key to grasping how Aquinas uses it is realising that he is referring to the effect of loving, rather than merely the act of loving. For the act of love leaves an ‘imprint’ of the beloved in the lover that ‘moves and pushes the will of the lover toward the beloved.’[18] Love proceeding is this imprinted ‘principle of impulsion’.[19] Love is not just a relationship between a lover and the object loved, but it also ‘the relation to its principle, of what proceeds by way of love.’[20] Such a use of the term is ‘an accommodation’ and not ‘the proper meaning.’ However, by embracing an accommodation, Giles Emery believes Aquinas is able to avoid understanding it ‘as an appropriation (the danger of some medieval interpretations of Augustine), confusing the Holy Spirit with God’s nature as love.’[21] Christopher Holmes concludes while this ‘‘language of “will” is not the language of Scripture, Thomas thinks it illuminates Scripture.’[22] This assignment argues that Aquinas is correct in thinking this, for it illuminates what Scripture teaches about the person and work of the Spirit.

The Person of the Holy Spirit

Having clarified what Aquinas means when he describes the Spirit as love proceeding, this assignment now demonstrates how it illuminates his (1) divine person and (2) eternal relations. In relation to the Spirit’s divinity, Aquinas sometimes seeks to prove this from his actions and attributes. For example, he does this in Summa Contra Gentiles.[23] This same argument is used extensively by later theologians like John Calvin, William Ames, and Francis Turretin.[24] However, in Summa Theologica, Aquinas approaches the issue from a different perspective, for which love proceeding is of utmost importance. Instead of directly dealing with divinity, Aquinas begins by examining the processions in God. Having shown there are two processions, he holds there must be four divine relations. And from this reasoning on four divine relations, he deduces that there must be a plurality of three divine persons.[25] Only at this stage does he consider the persons of the Father, Son, and Spirit, given they are these three divine persons.[26] From this approach it is clear that Aquinas believes an alternative argument for the Spirit’s divinity is the connection between the processions, relations and persons in God. According to Aquinas, if the Spirit has an eternal procession, he is a divine person. This shows how crucial and illuminating love proceeding is for the Spirit’s person. For it not only describes his eternal procession and divine relations, but it also establishes his divinity. As Aquinas puts it, because the Spirit proceeds in God ‘by way of love and will’, he ‘must have divine being, and must be God.’[27] Further, it is also clear from this approach that love proceeding establishes the Spirit’s personhood. For if love is one of two processions in God, then love proceeding must be one of the three persons in God. It is because love proceeds, that ‘the Holy Spirit is Love in person.’[28]

While love proceeding sheds light on divine personhood, it is even more illuminating for eternal relations. Indeed, this is why Aquinas examines names so closely. Matthew Levering explains that he ‘devotes painstaking attention’ to the names of the divine persons as it is their proper names that ‘truly distinguishes the person from the other two by expressing the relative opposition in the order of origin.’[29] As Holmes states, ‘For Thomas, a name includes a relation. The name Love expresses particular relations of origin.’[30] We can see how this is the case by considering what Love reveals about the relations between the Father and the Son. As Emery argues, ‘this love is, as such, the mutual love of the Father and Son.’[31] Mutual love was part of Augustine’s understanding.[32] However, Aquinas develops it, arguing ‘without the Holy Spirit there would be no way of grasping a unity of connection between Father and Son.’[33] Thomas Weinandy explains love proceeding reveals ‘the Father’s paternal begetting-love for his Son’ and ‘the filial-love of the Son for his Father.’[34] However, love proceeding also illuminates the relations between the Father and Son and the Spirit himself. For as Aquinas argues, ‘from the fact that the Father and the Son mutually love one another, it necessarily follows that this mutual Love, the Holy Spirit, proceeds from both.’[35] In this way, it is a crucial argument in support of the filioque. While Aquinas’ main and most famous argument for this is opposed relations, Edward Siecienski points out that he also argues from the perspective of Love.[36] The underlying psychological analogy is a ‘solid framework’ within which we can comprehend something of the Spirit’s procession from the Son.[37] As Aquinas reasons, ‘love proceeds from the word, since we cannot love a thing unless we first conceive it in the word of our hearts.’[38] The simple suggestive power of this argument is clear to Aquinas, for in shorter works aimed more widely at the general public, he uses it to defend the Spirit’s procession from the Son, without even resorting to that of opposed relations.[39] Indeed, Aquinas is so convinced of this psychological analogy, that he is willing to stake the doctrine of the Trinity upon it. He asserts in Quaestiones Disputatae de Potentia Dei, ‘if the procession of the Word and Love does not suffice for suggesting personal distinction, there could not be any personal distinction in God.’[40] In this way, love proceeding not only illuminates who the Spirit is, both in his divine person and eternal relations, but it also sheds a remarkable light into the heart of the triune God.

The Work of the Holy Spirit

Having examined the explanatory power of love proceeding with respect to the Spirit’s person, this assignment now considers how it also illuminates his work, particularly in relation to (1) Christ, (2) creation, and (3) Christians. We should expect an expression of the Spirit in eternity to also enlighten his work in the economy, for ‘his temporal mission in salvation history is grounded in his eternal procession within the life of God.’[41] As Aquinas puts it, ‘the temporal procession is not essentially other than the eternal procession’.[42] This can firstly be seen with respect to Christ. As shown out above, ‘love has a connection of origin (an ‘order’) in relation to the Word.’[43] This is not only true in eternity, but also in the economy. For example, in the Spirit’s visible mission at Christ’s baptism (Matt 3:16), Love is suggestive for why the Spirit appears as a dove, a symbol of love, in the same moment as the Father is declaring his love. Similarly, it also illuminates the Spirit’s invisible mission, for love proceeding helps to explain why the work of the Spirit is constantly centred on Christ. Aquinas argues ‘just as love proceeds from the truth, so love leads to knowledge of the truth.’[44] This procession from the truth is the Spirit’s procession from the Son (John 14:16; 16:14). As Holmes puts it, ‘The Spirit speaks Jesus Christ because the Spirit proceeds from Christ.’[45] In this way, love proceeding helps makes sense of the fact that the Spirit is so often closely associated with the concept of truth. For as the Love that proceeds from the Word, he also leads us back to the Word.

            The description of love proceeding also sheds light on the Spirit’s work in creation. Aquinas holds that God’s goodness causes him to will other things into existence. Therefore, he reasons ‘the love whereby he loves his own goodness is the cause of things being created.’[46] This helps to explain the common texts on the Spirit’s work in creation (Gen. 1:2; Ps. 104:30). From Genesis 1:2, Aquinas also argues that as ‘love is an impelling and moving force, any movement that God causes in things is rightly appropriated to the Holy Spirit.’[47] Therefore, he concludes that the Holy Spirit is also central in how ‘God directs and moves all things to their respective ends.’[48] For this reason, he ascribes God’s government of the world  and ‘the entire working of divine providence’ directly to the Spirit (Job 33:4; Ps. 143:10).[49] Indeed, Aquinas even argues that life itself can be ascribed to the Spirit as love. While he draws on several texts to support of this (Ezek. 37:6; John 6:64), along with the language of ‘the giver of life’ in the Nicene Creed, he also argues it from the perspective of love proceeding.[50] Afterall, we identity life in a creature by movement, and movement and impulse belong to the procession of will.[51] In this way, Aquinas shows that love proceeding gives us the light to see creation as ‘a work of love’, with the Spirit as ‘the Love who gives life and who leads creatures to their fulfillment.’[52]

            Finally, love proceeding also illuminates the work of the Spirit in the lives of Christians. This is particularly clear in Summa Contra Gentiles, where we see how it ‘proves its worth by enabling one to grasp multiple aspects of the economy of the Spirit.’[53] For rather than viewing love to be ‘a mere accidental perfection of the human soul’, Aquinas argues the Spirit is ‘the cause of all the perfections of man’s soul.’[54] He argues this from Romans 5:5, a key verse in his understanding of love proceeding. Further, from John 14:23 and 1 John 3:24, he concludes ‘since charity, whereby we love God, is in us from the Holy Spirit, it follows that the Holy Spirit is in us so long as charity remains in us.’[55] This indwelling love of God results in a friendship (John 15:15), from which all the blessings and privileges of the Christian life flow. This friendship through the Spirit means that all the gifts of God are given to us (1 Cor. 12:8), we are enabled to perform good works (Eph. 1:13), we are adopted as sons (Rom. 8:15), and we receive forgiveness for sins (Isa. 4:4). Further, it is also through this friendship in the Spirit that ‘we rejoice in God, and are comforted in all the hardships and afflictions of the world.’[56] Friendship means ‘that a man consent to the things which his friend wills.’[57] Therefore, love proceeding brings about our obedience (John 14:15). For ‘as the Holy Spirit makes us lovers of God, it is he also who leads us to fulfill the commandments of God.’[58] In all these ways, Aquinas shows that describing the Spirit as love proceeding, and understanding the friendship that flows from this, illuminates his work in Christians. For in relation to the blessings of the Christian life, he shows that the banner over them all is Love, being the Spirit proceeding as love.

Conclusion

It has been said that Aquinas ‘towers over the rest of medieval theology’.[59] However, given the light he sheds on the person and work of the Holy Spirit, that tower could be called a lighthouse. As shown in this assignment, his description of love proceeding illuminates extensive elements of the Spirit’s person and work. Emery summarises it well when he says, ‘the profound value of this idea’ is that it ‘bypasses the heresies and, so far as theology can do so, transmits an authentic grasp of the Trinitarian mystery.’[60] Of course, not everyone is convinced. For example, Anthony Thiselton describes the concept as ‘unduly technical for today’s readers.’[61] Similarly, Aquinas is accused of ‘subordinating the doctrine of the Trinity to a philosophically determined account of God’s life.’[62] Indeed, we must admit his exegetical arguments often go beyond what contemporary exegetes see in the same passages.[63] And the analogy of procession by way of intellect and will is not comprehensively set out in Scripture.[64] Nevertheless, we must remember that systematic theology can establish its validity not merely by whether it can be explained from Scripture, but also by whether it can explain things in Scripture. It appears that Aquinas has listened to how John speaks with respect to the Son (John 1:1) and has learnt to speak that same language in relation to the Spirit. [65] Indeed, this is shown in the fact that love proceeding helps to shed a remarkable amount of light on the later Johannine texts on the person and work of the Holy Spirit. It is because the Spirit proceeds as love from the Father and Son, that he bears witness about the Son and causes us to keep his commandments (John 14:15–17; 15:26-27; 16:13-15). Musicians can discern whether a note is right by reading it from the music. However, they can also do so by listening to how it harmonises with the rest of the notes being played. Theologians must learn to do the same. We should acknowledge the importance of love proceeding based on its extensive explanatory power for the rest of the person and work of the Holy Spirit.

[1] Aquinas, Summa Theologica, I q36.

[2] Aquinas, Summa Contra Gentiles, IV 19.

[3] Aquinas, Summa Theologica, I q36.

[4] St Gregory of Nazianzus, Oration 31, 29.

[5] Gilles Emery, The Trinitarian Theology of Saint Thomas Aquinas, trans. by Francesca Aran Murphy (Oxford, 2007), 219.

[6] Aquinas, Summa Theologica, I q36–38.

[7] Emery, The Trinitarian Theology of Saint Thomas Aquinas, 220.

[8] Matthew Levering, Engaging the Doctrine of the Holy Spirit: Love and Gift in the Trinity and the Church (Grand Rapids, 2016), 67.

[9] Aquinas, Summa Contra Gentiles, IV 18.

[10] Stephen R. Holmes, The Holy Trinity: Understanding God’s Life (Milton Keynes, 2012), 157.

[11] Augustine, De Trinitate, XV 22.

[12] Aquinas, Summa Contra Gentiles, IV 26.

[13] Aquinas, Summa Contra Gentiles, IV 26.

[14] Thomas Joseph White, The Trinity: On the Nature and Mystery of the One God (Washington, DC, 2022), 482.

[15] Aquinas, Summa Theologica, I q27 a3.

[16] Aquinas, Summa Theologica, I q37 a1.

[17] White, The Trinity, 488.

[18] Gilles Emery, The Trinity: Introduction to Catholic Doctrine on the Triune God (Washington DC, 2011), 152.

[19] Emery, The Trinity, 152.

[20] Aquinas, Summa Theologica, I q37 a1.

[21] Emery, The Trinitarian Theology of Saint Thomas Aquinas, 232.

[22] Christopher Holmes, The Holy Spirit (Grand Rapids, 2015), 109.

[23] Aquinas, Summa Contra Gentiles, IV 17.

[24] John Calvin, Institutes of the Christian Religion, I cXIII p14-15; Francis Turretin, Institutes of Elenctic Theology (Phillipsburg, 1992), 305–307; William Ames, The Marrow of Sacred Divinity (London, 1642), 19–20.

[25] Aquinas, Summa Theologica, I q27, 28, 29–30.

[26] Aquinas, Summa Theologica, I q33–38.

[27] Aquinas, Summa Contra Gentiles, IV 23.

[28] Emery, The Trinity, 151.

[29] Matthew Levering, ‘Roman Catholic Perspectives’, T&T Clark Handbook of Pneumatology (London, 2020), 184.

[30] Holmes, The Holy Spirit, 88.

[31] Emery, The Trinitarian Theology of Saint Thomas Aquinas, 227.

[32] Augustine, De Trinitate, VI 5.7; XV 17.27–18.32.

[33] Aquinas, Summa Theologica, I q39 a8.

[34] Thomas G. Weinandy, ‘The Filioque: Theology and Controversy’, T&T Clark Handbook of Pneumatology (London, 2020), 180.

[35] Aquinas, Summa Theologica, I q37 a1.

[36] A. Edward Siecienski, The Filioque: History of a Doctrinal Controversy (Oxford, 2010), 128.

[37] Gilles Emery, Trinity in Aquinas (Ann Arbor, 2006), 257.

[38] Aquinas, Summa Contra Gentiles, IV 24; Aquinas, Summa Theologica, I q27 a3, q36 a2.

[39] Emery, Trinity in Aquinas, 258.

[40] Aquinas, Quaestiones Disputatae de Potentia Dei, q9 a9 ad7.

[41] Fred Sanders, The Holy Spirit: An Introduction (Wheaton, 2023), 45.

[42] Aquinas, Commentary on the Sentences, I d16 q1 a1.

[43] Emery, The Trinitarian Theology of Saint Thomas Aquinas, 226.

[44] Aquinas, Commentary on the Gospel of John, 14.4 p1916.

[45] Holmes, The Holy Spirit, 87.

[46] Aquinas, Summa Contra Gentiles, IV 20.

[47] Aquinas, Summa Contra Gentiles, IV 20.

[48] Aquinas, Summa Contra Gentiles, IV 20.

[49] Emery, The Trinitarian Theology of Saint Thomas Aquinas, 248.

[50] Aquinas, Summa Contra Gentiles, IV 20.

[51] Aquinas, Summa Contra Gentiles, IV 20.

[52] Emery, The Trinity, 155.

[53] Emery, The Trinitarian Theology of Saint Thomas Aquinas, 233.

[54] Aquinas, Summa Contra Gentiles, IV 18.

[55] Aquinas, Summa Contra Gentiles, IV 21.

[56] Aquinas, Summa Contra Gentiles, IV 22.

[57] Aquinas, Summa Contra Gentiles, IV 22.

[58] Aquinas, Summa Contra Gentiles, IV 22.

[59] Holmes, The Holy Trinity, 154.

[60] Emery, The Trinitarian Theology of Saint Thomas Aquinas, 226.

[61] A.C. Thiselton, The Holy Spirit: In Biblical Teaching, through the Centuries, and Today (London, 2013), 244.

[62] Holmes, The Holy Trinity, 155.

[63] Levering, Engaging the Doctrine of the Holy Spirit, 68.

[64] Gregg R. Allison, and Andreas J. Köstenberger, The Holy Spirit (Nashville, 2020), 267.

[65] Holmes, The Holy Spirit, 100.