Excerpt from the Preface: In one of the most brilliant of modern books its author 1] calls attention to the common fallacy which assumes that "if you can find a principle which gives an adequate explanation of three different facts it is more likely to correspond with the truth than three different principles which give adequate explanations of the same facts severally." This fallacy underlies much that is being urged in favour of a common origin for religious doctrines and methods of worship. A single source of religious belief or of religious phenomena is preferred to several sources as being more tidy and more in keeping with what we have learnt to expect in other departments of research. It may be illogical, but still it is recommended as a safe guide to the truth. Indeed, it is difficult for a modern student to conceive how any real advance can be made in scientific pursuits unless the principle, which prefers one explanation of phenomena to many, is favoured.