I propose in this work to trace out in rough outline the evolution of the idea of God from its earliest and crudest beginnings in the savage mind of primitive man to that highly evolved and abstract form which it finally assumes in contemporary philosophical and theological thinking.In the eyes of the modern evolutionary enquirer the interest of the origin and history of this widespread idea is mainly psychological. We have before us a vast and pervasive group of human opinions, true or false, which have exercised and still exercise an immense influence upon the development of mankind and of civilisation: the question arises, Why did human beings ever come to hold these opinions at all, and how did they arrive at them? What was there in the conditionsof early man which led him to frame to himself such abstract notions of one or more great supernatural agents, of whose objective existence he had certainly in nature no clear or obvious evidence? Regarding the problem in this light, as essentially a problem of the processes of the human mind, I set aside from the outset, as foreign to my purpose, any kind of enquiry into the objective validity of any one among the religious beliefs thus set before us as subject-matter. The question whether there may be a God or gods, and, if so, what may be his or their substance and attributes, do not here concern us. All we have to do in our present capacity is to ask ourselves strictly, What first suggested to the mind of man the notion of deity in the abstract at all? And how, from the early multiplicity of deities which we find to have prevailed in all primitive times among all human races, did the conception of a single great and unlimited deity first take its rise? In other words, why did men ever believe there were gods at all, and why from many gods did they arrive at one? Why from polytheism have the most advanced nations proceeded to monotheism?To put the question in this form is to leave entirely out of consideration the objective reality or otherwise of the idea itself. To analyse the origin of a concept is not to attack the validity of the belief it encloses. The idea of gravitation, for example, arose by slow degrees in human minds, and reached at last its final expression in Newton's law.