The German Catholic philosopher, theologian, and bishop Klaus Hemmerle (1929-1994) is known primarily as the author of a prophetic treatise Theses Towards a Trinitarian Ontology (1976). The recent theological, metaphysical, or phenomenological engagement with Hemmerle's work in Germany, Italy, and elsewhere stimulated new interest in the philosophical meaning of the Trinitarian mystery. How are we to understand the meaning of the created gift of being if its divine giver is God the Father, the Son, and the Holy Spirit? How does our understanding of reality change if its meaning is Trinitarian self-giving? The monograph "The Self-Giving of Christ: A Christological Fundament of Klaus Hemmerle's Trinitarian Ontology" approaches these questions from a Christological perspective in relation to the entire theological and philosophical work of Klaus Hemmerle. The practical following of Jesus Christ brings us to the mystery of his both creatural and divine self-giving. By radically mediating the utmost reality of God's interpersonal love, Christ's self-giving becomes the starting point for a renewed understanding of being in Christian ontology or metaphysics.
The author therefore first explores various historical forms of the relationship between Christology and metaphysics. Against this background, he identifies the specific significance of Klaus Hemmerle's work, emphasizing its connection to Hemmerle's Christian life and ministry. The systematic reconstruction of the Christological fundament of Klaus Hemmerle's Trinitarian ontology then points to Christian metaphysics as a metaphysics of suffering and love, which opens up in a horizon of being defined on the one hand by the abysmal "why" of all suffering, and on the other by the abysmal and extreme love that takes this suffering upon itself. Thus, a meaningful metaphysical reflection, beginning at once in wondering joy at the nearness of the Word and in shaken compassion at the suffering of the Flesh, must be a systematic integration of these two mysteries. The proper place of this integration is the life of man. A true metaphysical reflection only makes explicit and clarifies what is essentially taking place in the patient daily life and thought of ordinary people.