Towards the end of a fruitful life, Karl Barth sensed the need for a more satisfactory theology of the Holy Spirit. He could not write this work himself or even indicate its shape, but this work by Andrew Gabriel comes reasonably close to doing so and points a way forward. This young pentecostal scholar lays out a profound vision of the Trinitarian Spirit, incorporating some of the fresh thinking which becomes possible when full justice is done to this subject matter. I think it not too rash to see this volume marking a new phase in the development of Pentecostal systematic theology.