The Holy Spirit, via "appropriation", partakes in the actions of the trinity, because God is "unified in will" and "unified in activity". When the Son acts the Holy Spirit acts, as does the Father, because God acts in unity.(Module 5.1.5) Every work of God is initiated, perpetuated, and compleated (according to Gregory of Nyssa). The Holy Spirit is often seen in scripture enacting compleation in the unified work of God. (Trinity and Christology lecture on the Cappadocians)