[19] _Golden Bough_, 3rd ed., i. 337. CHAPTER THREE THE RELIGION OF MENTAL DISEASE "It is an interesting problem," says Professor J. H. Leuba, "to determine what influences have led theologians to anchor their beliefs upon the proposition that religious experience differs from other forms of consciousness in that it gives one an _immediate_ knowledge of the external existence of certain objects of belief, although they do not fall under the senses, and an immediate knowledge of the truth of certain historical facts."[20] This is, indeed, an interesting problem, and, we may add, one of growing importance, since there is a pronounced tendency on the part of present-day exponents of religion to rest their case almost entirely upon the immediacy of their religious consciousness. This conception of a certain order of experience, however, is not and cannot have always existed. A belief may be so widely and so generally diffused that it is accepted without resistance, and, as it would almost seem, in the absence of evidence. But its intuitive character is only superficial, and disappears on careful examination. The mere vogue of a belief constitutes in itself a kind of evidence, and for many people the most powerful kind of evidence. But the conviction itself has a history, and it is in the unravelling of that history, in the discovery of the class of facts upon which the conviction has been built, that the work lies. And when this is done it will be found that our intuitions are invariably based upon a continuous--even though partly unconscious--appeal to facts. Sometimes it will, of course, be found that a renewed and deliberate appeal to the facts in question will justify the conviction. At other times it will be found that the facts demand an altogether new interpretation. For centuries all the observed facts supported a conviction that the earth was flat. It was a fresh scrutiny of the facts in the light of a new conception that revolutionised human opinion on the subject.