Andrew Robinson, medical doctor and honorary fellow in theology at the University of Exeter, wrote this book convinced that “Trinitarian thought should be a framework that makes sense of the entirety of Christian life” (ix). For that purpose he had recourse to the philosophy of signs (semiotics) originally set forth by Charles Sanders Peirce. The book is divided into three parts. In the first part, Robinson sets forth Peirce's scheme of Quality, Otherness, and Mediation as “elemental grounds” for human understanding and interpretation of physical reality (21) and applies these terms to the Father, Son, and Holy Spirit: the Father is Quality or “in-itself-ness” (20), the Son is Otherness as the self-manifestation of the Father, and the Holy Spirit is Mediation between the Father and the Son. The mutual indwelling (perichoresis) of Father, Son, and Holy Spirit can thus be explained as a semiotic process in which each divine person plays a distinct but interrelated role. With reference to creatures, Jesus as the Word Incarnate is thus the iconic self-representation of the Father to creatures in and through the mediation of the Spirit (53).

In part 2, “Sharing God's Life,” Robinson claims that Christians participate in the divine life by using the guidance of the Spirit to interpret the significance of Christ as the Word Incarnate both for their own spiritual development and for insight into the meaning and value of the events that they encounter in everyday life. Furthermore, the sacraments of the church are sacred signs that should be used by Christians to deepen their participation in the divine life (71). Communal celebration of the sacrament of the Eucharist, for example, is the key way for a group of Christians to become the Body of Christ or the kingdom of God in a given locale (73–75). Similarly, the sacrament of baptism is not simply the conventional ritual for gaining membership in a given church community, but a sign to the parents, relatives, and friends that they have a new responsibility to nurture the Christ life within the newly baptized person (84–85). Finally, scapegoating others so as to avoid one's own responsibility for something that went wrong is exposed as hypocritical in light of the passion and death of Jesus as the innocent victim of our own deep-rooted sinful tendencies.

Part 3, “The Mystery of Existence,” presents a semiotic understanding of the overall God-world relationship, namely, that the categories of Quality, Otherness, and Mediation that explain our human use of signs to communicate both with one another and with the world around us have an iconic likeness to the governing pattern of divine life among the three divine persons (121). In my view, such an approach to the God-world relationship would be further strengthened if Robinson had linked it more closely with his other notion of a “semiotic matrix” as the womb or ground “in which our representation and understanding of the world grows” (137). For if this semiotic matrix for the world of creation is envisioned as incorporated into or participant in the semiotic matrix or ontological ground for the interrelated activity of the divine persons apart from creation, then the structure of the divine semiotic process necessarily provides the foundational structure of the semiotic process proper to creation as Robinson proposes.

Likewise, if Robinson had worked with the semiotics of Josiah Royce instead of Peirce's, he would have had a more obvious analogy for explanation of the doctrine of the Trinity. Royce claimed that a semiotic process properly involves three Interpreters, each of whom serves alternately as Quality, Otherness, and Mediation to the other two persons as they collectively interpret the signs of their life together. Thereby they constitute the higher-order corporate reality of a community with a shared past and a common future that deals with the world around it as a single unified agency. All that being said, this book is well worth reading if only for Robinson's reader-friendly explanation of technical terms in theology and science and for the artful way in which he uses Peirce's semiotics to present the sacraments as different ways to participate in the divine life even now.