“The Trinitarian Christology of Thomas Aquinas”

I wrote a review of Dominic Legge’s excellent book The Trinitarian Christology of Thomas Aquinas (Oxford University Press, 2017) for Reviews in Religion and Theology.

[This is the pre-peer reviewed version of the article, which has been published at: onlinelibrary.wiley.com/doi/abs/10.1111/rirt.13321]

The prevailing wisdom of twentieth-century theology—from Rahner and Balthasar to Moltmann and Jenson—has been that Thomas Aquinas’s Trinitarian doctrine is cut off from the events of salvation history: He divorced Christology from the Trinity such that the Son’s incarnate mission reveals nothing of the intra-Trinitarian life. Students of theology will be well aware of how far afield some have wandered in their search for an alternative approach. However, it turns out that these nomads would have been better served attending more closely to the writings of St Thomas, for the critiques of Rahner et al. were based on ‘a serious misunderstanding of Aquinas’s thought’ (p. 3). This is the contention of Dominic Legge in his excellent new book, The Trinitarian Christology of Thomas Aquinas.

Far from combing through the Tertia pars for references to the Father and the Spirit, Legge brings to light the Trinitarian insights that structure the whole of Aquinas’s theology. The book unfolds in three parts. The first of these explores how the eternal processions of the Son from the Father, and of the Spirit from the Father and Son (Aquinas holds fast to the filioque), which characterize all of God’s acts of creation and redemption, are extended into time in the divine missions. Aquinas maintains that ‘a mission includes the eternal procession, with the addition of a temporal effect’ (Summa Theologiae [ST] I, q. 43, a. 2 ad. 3; quoted on p. 17). While every divine action is efficiently caused by the whole trinity, the effect (or ‘terminus’) of a divine mission is properly related to a single divine person who is made uniquely present therein. In their invisible missions the Son and Spirit produce in creatures a likeness to their processions by which they dwell within the creature and lead them back to the father. Within their visible missions a key difference obtains, for while the presence of the Spirit is only signified visibly by a sign (e.g. the dove in John 1.32), the divine person of the Son is truly and uniquely made visible as the Word made flesh.

Part Two concerns Christ’s relation to the Father. It is true that Aquinas claims that any of the three divine persons ‘could have’ (potuit) become incarnate (ST III, q. 3, a. 5), and many have assumed that it is therefore irrelevant to St Thomas that it was the Son who took on flesh. However, Legge rightly maintains that St Thomas’s point is just the opposite: while it was within the absolute power of God to do otherwise, the Incarnation of the Son is ‘supremely fitting’ (convenientissimum) (p. 62). This fittingness, which is itself ‘a kind of conditional necessity in view of the whole of the dispensatio’ (p. 127), is illuminated by Christ’s designation as Word, Son, Image, and the ‘author of sanctification’ (Chapter 3). Legge skillfully brings to light the Trinitarian dimensions of the hypostatic union, explaining how Aquinas understands the ‘personal esse’ of the Word to exist in a uniquely filial mode of being, such that the ‘theandric’ words and actions of Christ reveal to us the Father (Chapter 4).

The final part concerns the relation between Christ and the Holy Spirit. Legge maintains, against those Thomists of the ‘substantial holiness’ position (p. 139), that in order to avoid a confusion of natures, we cannot simply say that the hypostatic union divinizes Christ’s humanity. The mediation of a created form is necessary, which is habitual grace: the invisible mission of the Spirit to Christ. At the same time, Legge disagrees with Jean-Pierre Torrell, who argues that habitual grace is only fitting, and not a necessary consequence of the hypostatic union. Legge agrees with Torrell that Christ’s habitual grace is formally distinct from the grace of union, but he maintains that it is nonetheless entailed by it, and he highlights three key ways in which this is so (Chapter 5). Legge’s answer to this debate is compelling and is sure to garner interest among students of Aquinas. The upshot is that he uncovers in Aquinas’s thought a robust Spirit-Christology in an orthodox vein that enables him to speak of Christ with respect to the presence and causality of the Son, the Spirit, and the whole Trinity, “each according to a different mode” (p. 158).

Chapter 6 highlights the role of the Spirit in Christ’s human knowledge. Unfortunately, Legge unhelpfully brackets out Jesus’ divine and acquired knowledge, playing into the stereotype that Thomists too easily divide the person of Christ when it comes to his knowledge and consciousness. Nonetheless, he provides a succinct and helpful discussion of the Spirit as both the cause of the lumen gloriae that enables Christ’s beatific vision of the father, and the one who imparts the habitual grace of infused knowledge to Christ’s human soul. Some discussion of the role of the beatific vision in bringing about the hypostatic synergy and instrumental unity of Christ’s two wills (cf. ST I, q. 82, a. 2) would have strengthened his argument and served to connect it more fully to the following chapter. In Chapter 7 Legge explains that while the humanity of Christ acts as an instrument of the divine Word by nature of the hypostatic union, it is also prepared with the ‘habitus’ for instrumental action (what Aquinas calls a ‘divine instinct’) by the gifts of the Spirit. He also notes Aquinas’s affirmation, contra Augustine, that Christ pours out the Spirit not only as God, but also as man (Chapter 8).

Legge’s argument does much to explain Aquinas’s emphasis on all Christ ‘did and suffered’ in the flesh (ST III, qq. 27-59) as a revelation of God in the fullest sense (p. 190). For Aquinas, the Trinitarian shape of the entire economy of grace emerges from the eternal processions of the Son and Spirit by knowledge and love, and this effects how he understands history: Christ is the visible manifestation of the Triune God, but only for those with eyes to see. The Spirit ‘infuses into us a love of Christ that permits us to seize upon the deepest mysteries of Christ’s identity as God made man who has come to save us’ (p. 228). Contrast this hermeneutic of love with Albert Schweitzer’s famous claim that the best of the ‘Lives of Jesus’ were written out of hate. This book is thus a valuable contribution to theological hermeneutics and an excellent complement to the work of Michael Sherwin and others on Aquinas’s integration of reason and will.

This dense but articulate monograph builds firmly on the work of Gilles Emery, who provides an enthusiastic foreword. Legge relies heavily on texts outside of the Summa Theologiae, especially Aquinas’s biblical commentaries, contributing to the ongoing recovery of the Dominican Master as magister in sacra pagina (a phrase Legge uses throughout to signal the exegetical substratum of St Thomas’s theology). He provides lyrical translations of the Latin texts, though specialized discussions and technical terminology will require readers to have some familiarity with Trinitarian theology. Given its relevance to various contemporary theological discussions, this book will be of interest not only to students of Thomas Aquinas, but anyone with an interest in systematic theology.