The Varieties of Religious Experience

Twenty lectures given as the Gifford Lectures in Edinburgh in 1901–02 and subtitled A Study in Human Nature. James sets aside churches and doctrines to study personal religious experience, drawing on a large collection of first-hand accounts. He first rejects "medical materialism", the idea that tracing an experience to a bodily cause settles its value; experiences should be judged by their fruits. He then contrasts the religion of healthy-mindedness with the "sick soul" that sees evil as real, examines the divided self and its unification, and studies conversion and saintliness, weighing the value of saintly lives. The lectures on mysticism give four marks of mystical states: ineffability, a noetic quality, transiency and passivity. In his conclusions James argues that religious experience points to a "more" continuous with the self, and that its truth must be tested by its effects in life.

It is still the classic study of religious experience from the inside, fair to believers and sceptics, and its descriptions of conversion and mysticism remain widely used in philosophy and psychology.