The book The Spirit of the Father and of the Son: Theological and Ecumenical Perspectives by François-Xavier Durrwell (1990) discusses the role of the Holy Spirit in his relationship with the Father and the Son in the mystery of the Trinity. The author emphasizes that the Holy Spirit is not merely a 'connector', but a divine person who arises from the loving relationship between the Father and the Son and is active in the work of salvation, especially in the resurrection of Christ and the life of the Church. He also examines classic theological debates, including the Filioque issue, with an open and dialogical approach. Overall, this book presents a profound theological reflection with an ecumenical nuance, with the aim of enriching shared understanding across Christian traditions regarding the role of the Holy Spirit in faith and the life of the Church.