Abstract

For Thomas Aquinas, the heart of Christian teaching is the doctrine of the Trinity, and this is the first specifically Christian topic that he turns to in Summa Theologiae. Historically speaking, Aquinas is one of the most important writers on the doctrine of the Trinity, and it is these writings that are addressed in this chapter. Aquinas takes for granted the substance of early texts on the Trinity such as the Creed of Asthanius, so his position is thoroughly orthodox. Consequently, his own treatment of the Trinity deals with three main topics, each of which is discussed separately: the relevance of philosophy to the doctrine; the divine processions, and hence the relations, involved in the Trinity; and the persons of the Trinity taken individually.