In 1938 and 1939 Karl Barth delivered the Gifford Lectures in the University of Aberdeen. According to the will of the founder, these lectures were established for the ‘promoting, advancing, teaching and diffusing’ of the study of natural theology. But Barth was, as he made plain on receiving the invitation, ‘an avowed opponent of all natural theology’. Three years earlier he had fiercely attacked his former theological associate, Emil Brunner, on this same question. He had then said of natural theology: ‘It has to be rejected a limine—right at the outset. Only the theology and the church of the antichrist can profit from it. The Evangelical Church and Evangelical theology would only sicken and die of it.’ When therefore he was asked to give the Gifford Lectures he was in a quandary. The way in which he resolved the problem has usually been treated, half-humorously, as an ingenious piece of theological juggling. In fact, however, when we consider it in relation to his attitude to natural theology in his controversy with Brunner and to his treatment of it in Church Dogmatics II.I, on the knowledge of God, and indeed against the background of the whole of his life's work, we can see that in his solution of this difficulty there is simply the same attitude sharpened to a clear-cut issue. What he did was to jettison natural theology completely and give an exposition of its opposite, the theology of revelation.