Like it or not, “there is no way to escape Thomas”. With this annotation, the Canadian historian Bernard McGinn introduces his book Thomas Aquinas’s Summa Theologiae: A Biography (Princeton, NJ: Princeton University Press, 2019).

The volume is by one of today’s most acclaimed scholars of medieval Christianity and has an original cut. It is not an introduction to Aquinas, nor an essay on the Summa as such, but is instead a biography of this outstanding work.

The Summa consists of one and a half million words and is divided into 2668 articles. Moreover, it has had over a thousand commentaries in history (only the Bible has received more), thus becoming a catalyst for theological and philosophical thought over the centuries.

Thomas Aquinas’s Summa Theologiae holds a unique place in Western religion and philosophy. Written between 1266 and 1273, it was conceived by Aquinas to be an instructional guide for teachers and novices and a compendium of all the approved teachings of the Catholic Church—and it was still unfinished at the time of Aquinas’s death.

The Jesuit Bernard Lonergan called the Summa a “synthesis of medieval culture”.

Thomas Aquinas’ world

In the first chapter, McGinn explores the intellectual world in which Thomas Aquinas lived. He particularly emphasizes the role of scholastic theology, i.e. a teaching method and style centered on the analysis of different quaestiones (issues, questions) on the basis of the waving and screening of various auctoritates (authorities).

Scholastic theology had become a coherent and teachable model of inquiry. The leader of this tradition was Peter Lombard (1096-1160) with his Sentences, a work which had become the standard textbook of theology at the medieval universities and that Thomas commented upon extensively.

The second chapter presents a succinct biography of Thomas and a quick introduction to his writings (over a hundred works attributed to him).

Here, McGinn argues that the traditional association of Thomas Aquinas with Aristotelianism must be intertwined with the impact of Platonism on his thought through Boethius and Dionysius the Areopagite and, above all, Augustine.

In Thomas, the easy classifications do not respond to the complexity of his philosophical and theological universe.

The Summa is a full-fledged scholastic work. Each article of which it is composed poses the question to be examined, exposes a series of arguments contrary to the position one wants to support, cites an authoritative text, argues in favor of a solution and, finally, responds in detail to possible objections.

Beyond the scholastic structure of the argument, in Thomas the central point is his acceptance of the Aristotelian starting point according to which science (and therefore also theology) is “certain knowledge through causes”.

The entire procedure is guided by reason, which does not reach to revealed truths (like the Trinity), but which for everything else (including the existence of God) is the instrument for knowing.

Reason proceeds in a circular motion: it starts from (Aristotelian) principles, argues up to conclusions, and returns to principles with a deeper understanding of the principles themselves. Even “sacred doctrine”, for Thomas, works in a similar manner.

It is clear that, at the bottom of this approach, one finds the recognition of the full feasibility of human reason as a natural capacity. Although touched by sin, human reason remains the reliable instrument for all knowledge (even knowledge of God).

Exitus-Reditus. But where is in?

To understand the heart of the theology of Aquinas, very enlightening pages are dedicated to the movement of the Summa based on the exitus-reditus model: all things come from God (exitus) and, in different ways, return to him (reditus).

This is the macro-structure of the Summa and the grand-motif of Thomistic theology. The movement starts with God and goes back to Him as a cirscle.In this Thomist view there are two basic problems, which McGinn does not discuss and which can only be briefly touched on.

The first is the cyclical, rather than linear trend of its trajectory: the Bible presents a plotline not of returning to the starting point, but of arriving at a goal that is no longer the starting point. The New Jerusalem is not the initial garden of Eden; the eschaton is no longer “in the beginning”. The Omega of the story is no longer its Alpha. In the biblical plot there is a historical-redemptive progress from creation to the new creation, more than a return to the origin.

The second problem is that, in the Thomist scheme of exitus-reditus, the breaking of the covenant (and therefore the breach of sin) is missing. There is creation (going out), there is redemption (coming back), but sin is missing.

Obviously Thomas has a theology of sin, but sin has no “architectural” importance. It is inside the back-and-forth movement, without a directional upheaval. For this reason, the Thomist tradition has been able to summarize its own worldview with the adage: “grace does not remove nature, but perfects it”; between nature and grace there is a distinction of order, but not a breach caused by sin.

For this reason, Thomism does not have a tragic understanding of sin and its consequences. For this reason, the relationship between nature and grace in Thomistic Roman Catholicism underestimates the effects of sin and has an optimistic view of human capacities in cooperating with salvation.

The grace of reditus corresponds to the nature of the exitus, but what about sin? In the context of this overall optimism, the Roman Church has built its inflated self-understanding and its sacramental mediation.

In light of these remarks, it is perhaps clearer why the new wine of the Protestant motif of “creation-fall-redemption” cannot fit in the old skin of Thomism of the exitus-reditus motif.

Sin entered the world and altered it to the point that redemption is not an elevation of nature nor an addition to it, but can be biblically explained in terms of regeneration, life out of death, light out of darkness, salvation out of reprobation.

Therefore, one can begin to perceive why the difference between Thomism and the evangelical faith touches on a crucial, structural, foundational point, even in the presence of terms and themes that are sometimes overlapping.

The Summa at the core of the Roman Catholic system

The second part of the book is dedicated to the biography of the Summa across the centuries, from the first wave of Thomism immediately following Thomas’s death up to the neo-Thomism of the 19th-20th century.

McGinn remembers in particular Tommaso de Vio, Cardinal Gaetano, at the turn of the fifteenth and sixteenth centuries, who clashed with Luther. It is well known that the German Reformer had an unquestionably negative understanding of Thomism. For him, Thomas was “the source and foundation of all heresy, all error and the obliteration of the Gospel”.

It is also interesting that at the Council of Trent a copy of the Summa was placed next to the Bible, symbolically signifying the elevation of Thomas’s work to a source of authority for the Roman Church. No wonder Thomas was recognized as a “doctor of the church” by Pope Pius V in 1567.

From that point on, Thomas became an immovable cornerstone of Roman Catholic theology. On the basis of the Summa, the Jesuit Robert Bellarmine would have built his anti-Protestant apologetics that became standard up to the first half of the 20th century.

Neo-Thomism found in Leo XIII a pope who wrote the encyclical Aeterni Patris (1879), in which he officially elevated the thought of Thomas Aquinas to be the normative theological system for Roman Catholicism.

McGinn recalls the controversies over the “modernists” who were not so much opposed to Thomas as to a “triumphalistic” or “authoritarian” form of Thomism.

In the twentieth century, McGinn identifies four strands of Thomism still existing in the Roman Church:

• “Strict-Observance Thomism” (in the wake of Aeterni Patris: R. Garrigou-Lagrange, the “sacred monster of Thomism”);
• “Recovered Thomism” (M.-D. Chenu, Y. Congar, H. de Lubac);
• “Metaphysical Thomism” (J. Maritain, E. Gilson);
• “Transcendental Thomism” (P. Rousselot; J. Maréchal, K. Rahner).

Although Thomism is a legacy that is variously assimilated and understood, its permanent and pervasive influence on Roman Catholicism is undeniable. McGinn refers to the fact that Aquinas is cited in the texts of the Second Vatican Council (1962-1965) 734 times (the second most cited father is Augustine with 522 citations) and is cited in the Catechism of the Catholic Church (1994) 61 times.

Moreover, according to Thomas G. Guarino in The Disputed Teachings of Vatican II: Continuity and Reversal in Catholic Doctrine (Grand Rapids, MI: Eerdmans, 2018), the real theological mind behind Vatican II is not a modern theologian but Thomas Aquinas himself.

It was Aquinas who “furnished the writers of the dogmatic texts of Vatican II with the bases and structure (les assises et la structure) of their thought; again, “while Thomistic language was absent at Vatican II, Thomist ideas were in plain sight”.

A modernized form of Thomism, perhaps away from the rigidity of 19th century Neo-Thomism, but always within the same tradition expanded in dialogue with the modern world, was and is the framework that provides “the bases and the structure” of Rome. Furthermore, John Paul II’s encyclical Fides et Ratio (1998) is a quintessentially Thomist reflection on the relationship between faith and reason.

Although no longer monumental (perhaps) and certainly not monolithic, Thomism is still “substantial” for Roman Catholicism, representing its main theological backbone. Giving the Summa a central place in the work of Thomas Aquinas and coming to terms with its “biography” allows us to access the radiography of what lies at the heart of Roman Catholicism then and now.

When we deal with the Summa and its impact across Church history we should be aware of the fact that we are not dealing with a generic work belonging to the “Great Tradition” which is common to all strands of Christianity. We are dealing with a specific account of it that Roman Catholicism consistently calls its own.

Leonardo De Chirico is an evangelical pastor in Rome (Italy). He is a theologian and an expert in Roman Catholicism.