This chapter discusses the Person of the Holy Spirit. The Holy Spirit is the third Person of the Trinity who proceeds eternally from the Father. In his work in Christology Athanasius made the relevant conceptual breakthrough, yet the church was rightly cautious in stating the ontology involved. Efforts to secure the filioque clause are not successful. There is merit in applying the biblical images of breath, rain, water, dove, wine, and oil. Later images focusing on force-field, bond of love, and light are interesting but light should be preferred, not least because it helps us make theological sense of the transfiguration of the Son.