Basilio Petra sees Christos Yannaras (b. 1935) as a philosopher and theologian whose refiguring, on the one hand, of Heidegger's refusal to define being in ontic terms and, on the other, of Wittgenstein's willingness to admit the inexpressible character of the mystical has led him to articulate a powerful vision of true human existence. This bold interpretation outlines the passage from an ontic 'mode of nature' governed by necessity to a 'mode of self-transcendence and self-offering' beyond the limitations of decay and death. In his native Greece, Yannaras revolutionised the way theology had been done for much of the twentieth century. This book examines the trajectory of Yannaras' thought from his initial encounter with Heidegger's philosophy to his formulation (via the tradition of the Greek Fathers) of a modern critical ontology. It is for both advanced students of philosophy and the growing scholarly audience interested in Yannaras' work. Written in accessible language that does not compromise intellectual rigour, it is the only survey of the development of Yannaras' philosophical thought as a whole.