A series of lectures examines individual religious experience through psychological analysis, classifying temperaments and phenomena such as healthy-mindedness, the sick soul, conversion, saintliness, and mysticism. The author draws extensively on autobiographical and literary case studies to illustrate how intense religious states affect personality and perception. He considers neurological and philosophical angles, debates the reality of unseen states, and describes processes that unify divided selves. The final lectures synthesize these observations into tentative philosophical conclusions about the practical value and varieties of religious life.