Religion, it has already been said, is something that is acquired, and although that sounds little better than a commonplace, yet reflection proves it to contain an important truth. For it is in the nature of the acquisition that its significance lies. Whatever be the earliest stages of religion it is at all events clear that its earliest form is in the nature of a hypothesis, even though only of the semi-conscious kind that exists when man is brought into touch with some new and overpowering experience. Religious ideas are put forth in explanation of something. But all explanation whether by savage or civilised man, must be in terms of existing knowledge. No other method is possible. We must explain the unknown in terms of the known, and our explanation will be the more elaborate and the nearer the truth as our knowledge of the nature of the forces are the more exact and extensive. A knowledge of the laws of condensation and evaporation enables a modern to give an explanation of the meaning of a shower of rain that is simply impossible to man in an earlier stage of culture. In every case the facts are the same, and in each case the explanation given depends upon the knowledge acquired.
Now one radical distinction between an early and a modern explanation of the world is that whereas the former moves from within outward, the latter moves from without inward. Uncivilised man explains the world by himself; civilised man explains himself by the world. The savage describes the world in terms of his own feelings and passions, the scientist regards human qualities as resulting from the relation which man holds to the forces around him. The process, while presenting a radical difference in form, is yet fundamentally one in essence. Ignorant of all that we connote by such an expression as "natural forces," whatever explanation is offered by the savage is necessarily in terms of the only force with which he is acquainted. But it happens that the only forces which he then fancies he understands are those represented by his own organisation. What he is conscious of doing is prompted by his own will and intelligence. He hurts when he is angry, he rewards when he is pleased, and he makes the same assumption regarding the things around him. So far as he explains nature he vitalises it. Vital force becomes the symbol of all force. And this result expresses a mental law that is universally operative. The civilised mind differs from the savage mind not because the brain functions differently in the two cases, but solely in consequence of the wider and truer knowledge of the causes of natural phenomena which civilised man possesses. We arrive at different conclusions because we start from different premises. Inevitably, therefore, the first attempt of man to deal with nature takes the form of assuming the operation of a number of personal intelligences. Natural objects are alive, and everything that happens to man, from the cradle to the grave, is thought of as being either alive or controlled by living beings. The world is filled with a crowd of ghostly beings exercising more or less discordant functions. Against this riot of gods the conception of natural law developes but slowly. Quite apart from the natural inertia of the human mind, the fact of questioning the power of these assumed beings involves to the primitive mind an element of grave danger. All sorts of things may happen if the gods are offended, and in self-defence the tribe feels bound to suppress the critic of religion and of religious ideas. But once the step is taken, the area over which the gods rule is to that extent restricted, and with that step Atheism may be said to be born.