Originally published in 1951, this title is a study in developmental psychology with special reference to the effect of various types of religion on mental health and religious experience. With instinct as a ‘disappearing category’ in the psychology of human nature, a new approach to the realization of a harmonious interior life has been made using a doctrine of biological and personality needs as a starting point. Human nature is acquired and is not a static datum. The interior conflicts, the development of conscience and the origin of guilt feeling, the morbid complexes and the character-trends resulting from these conflicts with their sense of guilt are all studied. A long chapter on the various methods of mental healing through the doctrines of psycho-somatic medicine, with a new approach to Spiritual Healing in particular, prepares the way for the final chapter on the types of religion which originate or accentuate psychological conflicts, and the kind of religion which leads to a basic sense of security and harmonious personality. The illustrations are nearly all taken from Dr McKenzie’s own thirty years’ experience of dealing with neurotic disorders.This volume contains the substance (greatly expanded) of the Tate lectures delivered in Manchester College, Oxford, in 1947, and repeated at the St Andrews Summer School of Theology in1948 and at Iona Community.