There is little doubt that in our time the temporal and the historical have acquired a new importance in human thinking. There is a tendency to see everything as swept along in the flux of becoming. Nothing remains static, and even theologians have come to doubt whether such notions as 'immutability' and 'impassibility' are essential characteristic of God. The permanent framework has disappeared and even metaphysical system are regarded as the products of history. Is everything then plunged into a relativism, or even that nihilism which Nietzsche foresaw? John Macquarrie considers this questions in a new exploration of the thought of Martin Heidegger, the twentieth-century philosopher who gave a central place in his thinking to the temporality and historicality not only of human existence but of being generally. He examines Heidegger's career and early writings, and then above all his magnum opus Being and Time, going on to discuss such issues as metaphysics and theology; tinghood, technology and art; thinking, language and poetry. By attending to these concepts, he believes, we may learn something of the impact on Christianity of the contemporary concern with time.