For a thousand years or more, from roughly AD 400 to AD 1450, the intellectual life of the west was dominated by Christian theology. Whatever views may be held as to the validity and as to the future of Christian doctrine, its influence in shaping the outlook of western man cannot be denied. As Thomas Carlyle put it, Christian theology was ‘a great heaven-high unquestionability, encompassing and interpenetrating the whole of life’. 1 Even the rise of the physical sciences, as Hooykaas has recently shown, 2 depended a great deal upon the world picture of the theologians. Psychology, because of its intimate connection with the subject matter of religion, was even more deeply influenced. In an age when there was retrogression rather than advance in the physical and biological sciences, psychology, because of its religious affinities, was by no means completely stagnant, but significantly extended its range.