Approaching religious experience as a subject of scientific study, William James used the methods he gained as a physiologist, psychologist and philosopher. Rather than basing the work on anthropological data collected personally, he used personal documents of individuals who had recorded their own experiences. The work is neither a theological treatise nor a history of religion, but rather ‘a descriptive survey’ of general tendencies shared among his subjects. Moreover, the study is not limited to a systematic explanation of the causes of individual religious experience, but focuses equally on the result of such experiences and the impact upon the person’s life.