Reginald LYNCH. The Cleansing of the Heart: The Sacraments as Instrumental Causes in the Thomistic Tradition. Washington D. C.: Catholic University of America Press, 2017. pp. 225. ISBN 978-0-8132-2944-7. Reviewed by Pablo MUNOZ ITURRIETA, Dominican University, Ottawa, ON.

Theological questions have always been shaped by metaphysics and the language of philosophy. This a correct move by all means, given that it is the duty of every Christian to find reasons for their faith. A new metaphysical framework and worldview has always offered new ways to interpret the revealed mystery of salvation. This is the purpose of this book, that is, to show theological discussions that attempted to explain how it is that the sacraments affect a cleansing of the heart, a phrase borrowed from St. Augustine and employed by Aquinas, and which describes the effects that natural elements such as water or bread have on the human person when taken up by the Church as sacramental signs. Thus, the book is concerned with the theological question of sacramental causality from a Thomistic and a variety of other perspectives from the Scholastic Period to the modern discussions following the Council of Trent. Though centered on the sacraments, Reginald Lynch also directs our attention to the implications of sacramental causality for other areas of theology, such as Christology, merit, and grace. 

This is an excellent book to explore how the doctrine of instrumental causality describes the causal link between sacramental efficacy and the instrumentality of the Incarnation itself. For Aquinas, the humanity of Christ is an instrument of his divinity, and it is in that sense that the sacraments are an extension of Christ himself, causing in the soul of the one receiving the sacrament a communion with God himself through grace and the forgiveness of sins. 

Chapter 1 traces the history of sacramental causality as a theological topic, which begins with Augustine sacramental theology and his later influence in the Scholastic period. Lynch notes here how different approaches to sacramental causality emerged gradually and from very different theological perspectives, from Lombard to Aquinas, to the Franciscan School, to modern thinkers such as Melchior Cano, the implications of the Council of Trent, and contemporary discussions on sacramental theology.

Chapter 2 deals with Aquinas’ description of the sacraments as causes in his Commentary on the Sentences. This represents Aquinas’ early thought on sacramental causality, as he strived to offer a cogent interpretation of Augustine’s sacramental language by offering a metaphysical framework that preserves the intrinsic nature of divine power working through material signs.

Chapter 3 shows the development of Aquinas’ understanding of the metaphysical framework for instrumental causality, and the deeper integration between grace, sacramentality, merit, and Christology. This progression is especially seen in Aquinas’ Summa Theologica, where Thomas offers a rich metaphysical approach to the moral life of the human person and the work of grace through the sacraments.

The final chapter addresses developments within the modern period outside of the Thomistic school in the period following the Council of Trent. In a particular way, the chapter presents the theory of moral causality as developed by Melchior Cano. Lynch critically examines the implications of this theory from a Thomistic perspective, and successfully shows that this alternative does not satisfy the theological demands of the reality of the sacraments as was instead accomplished by Aquinas’ theory of instrumental causality.

This is a book highly recommended for graduate theology courses, as well as for courses on Thomistic metaphysics, and for anyone interested in a strong philosophical framework to explain the reality of the sacraments. We live in a post-Kantian world where, sadly, metaphysically realist solutions to question of causality are avoided, and for that reason this book is a much-needed contribution to the theological understanding of the sacraments.