Communion is a dynamic reality – love, unity of life, mutual penetration, the closest union. The Holy Spirit is the Communion within the Trinity and forms the communion between God, man and the world, between people, in the Church and within whole reality of this world. Showing pneumatology as a dimension of the entire dogmatic theology determines the originality of this monograph. Typically, theologians focused their works on pneumatology itself. Marek Jagodziński's monograph is especially up to date since the pentecostal awakening in Christianity carries certain dangers. They take the forms of over-exposing the Holy Spirit at the expense of the Son of God, overly simplified ecumenism, emphasising charisms over the institution and putting personal experience over the community faith of the Church. The study is not only a presentation of ideas but brings new and inspiring elements to the scientific discussion. It is an original and creative contribution to the theoretical achievements of theology as a discipline of science. The dissertation brings a new name for the Third Divine Person – Communion in the Holy Trinity. Communion reflects the mission of the Holy Spirit which embraces the Church and the sacraments, voices a golden mean between forgetting about the Holy Spirit and the Joachimism of proclaiming the era of the Holy Spirit. The monograph justifies the simultaneous existence of Christology and pneumatology, brings a new perspective on Filioque and is of significance for ecumenism.