On the Holy Spirit (De Spiritu Sancto)

Basil of Caesarea explains at the start how the book came to be written. At public prayer he had used two forms of the doxology, glory to the Father “through the Son in the Holy Spirit” and glory to the Father “with the Son together with the Holy Spirit”, and some of those present accused him of innovation. Amphilochius, bishop of Iconium, asked him for a reasoned account (1.3). The translator’s preface connects the request with the visits Amphilochius paid to Caesarea from 374, which dates the work to about 375.

The treatise argues from Scripture, from the baptismal formula and from the worship of the church that the Spirit is not a creature and is to be honoured with the Father and the Son. His friend Gregory of Nazianzus says that Basil deliberately refrained in public from stating in so many words that the Spirit is God, as a concession to the difficulties of the time (Oration 43.68–69). The work is a primary source for Basil’s own teaching and for the liturgical practice he appeals to, including his statement that some customs rest on unwritten tradition (27.66).