This text presents a collection of the 20 lectures written by the author for the Gifford Lectures on Natural Religion which were delivered at the University of Edinburgh, Scotland, from 1901 to 1902. The lectures attempt to provide a summary of man's various religious characteristics and experiences. Major topics of discussion include: religion and neurology; the reality of the unseen; the religion of healthy-mindedness; the sick soul; the divided self, and the process of its unification; conversion; saintliness; mysticism; philosophy; and various other elements of religion. The author warns that, in his belief that a large acquaintance with particulars often makes us wiser than the possession of abstract formulas, however deep, these lectures have been loaded with concrete examples chosen from the extremer expressions of the religious temperament. However, these religious impulses are, in the end, combined with other principles of common sense which serve as correctives of exaggeration, and allow the individual reader to draw as moderate conclusions as he will. (PsycINFO Database Record (c) 2004 APA, all rights reserved).