Our argument may fitly begin with an inquiry into the sources of the theistic idea and the shape which it has universally assumed among untutored men. The most primitive element which it contains is doubtless the notion of dependence upon something outside of ourselves. We are born into a world consisting of forces which sway our lives and over which we can exercise no control. The individual man can indeed make his volition count for a very little in modifying the course of events, but this end necessitates strict and unceasing obedience to powers that cannot be tampered with. To the behaviour of these external powers our actions must be adapted under penalty of death. And upon grounds no less firm than those on which we believe in any externality whatever, we recognize that these forces antedated our birth and will endure after we have disappeared from the scene. No one supposes that he makes the world for himself, so that it is born and dies with him. Every one perforce contemplates the world as something existing independently of himself, as something into which he has come, and from which he is to go; and for his coming and his going, as well as for what he does while part of the world, he is dependent upon something that is not himself.

Between ancient and modern man, as between the child and the adult, there can be no essential difference in the recognition of this fundamental fact of life. The primitive man could not, indeed, state the case in this generalized form, any more than a young child could state it, but the facts which the statement covers were as real to him as they are to us.[A] The primitive man knew nothing of a world, in the modern sense of the word. The conception of that vast consensus of forces which we call the world or universe is a somewhat late result of culture; it was reached only through ages of experience and reflection. Such an idea lay beyond the horizon of the primitive man. But while he knew not the world, he knew bits and pieces of it; or, to vary the expression, he had his little world, chaotic and fragmentary enough, but full of dread reality for him. He knew what it was to deal from birth until death with powers far mightier than himself. To explain these powers, to make their actions in any wise intelligible, he had but one available resource; and this was so obvious that he could not fail to employ it. The only source of action of which he knew anything, since it was the only source which lay within himself, was the human will;[3] and in this respect, after all, the philosophy of the primeval savage was not so very far removed from that of the modern scientific thinker. The primitive man could see that his own actions were prompted by desire and guided by intelligence, and he supposed the same to be the case with the sun and the wind, the frost and the lightning. All the forces of outward nature, so far as they came into visible contact with his life, he personified as great beings which were to be contended with or placated. This primeval philosophy, once universal among men, has lasted far into the historic period, and it is only slowly and bit by bit that it has been outgrown by the most highly civilized races. Indeed the half-civilized majority of mankind have by no means as yet cast it aside, and among savage tribes we may still see it persisting in all its original crudity. In the mythologies of all peoples, of the Greeks and Hindus and Norsemen, as well as of the North American Indians and the dwellers in the South Sea islands, we find the sun personified as an archer or wanderer, the clouds as gigantic birds, the tempest as a devouring dragon; and the tales of gods and heroes, as well as of trolls and fairies, are made up of scattered and distorted fragments of nature-myths, of which the primitive meaning had long been forgotten when the ingenuity of modern scholarship laid it bare.[4]

In all this personification of physical phenomena our prehistoric ancestors were greatly assisted by that theory of ghosts which was perhaps the earliest speculative effort of the human mind. Travellers have now and then reported the existence of races of men quite destitute of religion, or of what the observer has learned to recognize as religion; but no one has ever discovered a race of men devoid of a belief in ghosts. The mass of crude inference which makes up the savage's philosophy of nature is largely based upon the hypothesis that every man has another self, a double, or wraith, or ghost. This "hypothesis of the other self, which serves to account for the savage's wanderings during sleep in strange lands and among strange people, serves also to account for the presence in his dreams of parents, comrades, or enemies, known to be dead and buried. The other self of the dreamer meets and converses with the other selves of his dead brethren, joins with them in the hunt, or sits down with them to the wild cannibal banquet. Thus arises the belief in an ever-present world of ghosts, a belief which the entire experience of uncivilized man goes to strengthen and expand."[5] Countless tales and superstitions of savage races show that the hypothesis of the other self is used to explain the phenomena of hysteria and epilepsy, of shadows, of echoes, and even of the reflection of face and gestures in still water. It is not only men, moreover, who are provided with other selves. Dumb beasts and plants, stone hatchets and arrows, articles of clothing and food, all have their ghosts;[6] and when the dead chief is buried, his wives and servants, his dogs and horses, are slain to keep him company, and weapons and trinkets are placed in his tomb to be used in the spirit-land. Burial-places of primitive men, ages before the dawn of history, bear testimony to the immense antiquity of this savage philosophy. From this wholesale belief in ghosts to the interpretation of the wind or the lightning as a person animated by an indwelling soul and endowed with quasi-human passions and purposes, the step is not a long one. The latter notion grows almost inevitably out of the former, so that all races of men without exception have entertained it. That the mighty power which uproots trees and drives the storm-clouds across the sky should resemble a human soul is to the savage an unavoidable inference. "If the fire burns down his hut, it is because the fire is a person with a soul, and is angry with him, and needs to be coaxed into a kindlier mood by means of prayer or sacrifice." He has no alternative but to regard fire-soul as something akin to human-soul; his philosophy makes no distinction between the human ghost and the elemental demon or deity.

It was in accordance with this primitive theory of things that the earliest form of religious worship was developed. In all races of men, so far as can be determined, this was the worship of ancestors.[7] The other self of the dead chieftain continued after death to watch over the interests of the tribe, to defend it against the attacks of enemies, to reward brave warriors, and to punish traitors and cowards. His favour must be propitiated with ceremonies like those in which a subject does homage to a living ruler. If offended by neglect or irreverent treatment, defeat in battle, damage by flood or fire, visitations of famine or pestilence, were interpreted as marks of his anger. Thus the spirits animating the forces of nature were often identified with the ghosts of ancestors, and mythology is filled with traces of the confusion. In the Vedic religion the pitris, or "fathers," live in the sky along with Yama, the original pitri of mankind: they are very busy with the weather; they send down rain to refresh the thirsty earth, or anon parch the fields till the crops perish of drought; and they rush along in the roaring tempest, like the weird host of the wild huntsman Wodan. To the ancient Greek the blue sky Uranos was the father of gods and men, and throughout antiquity this mingling of ancestor-worship with nature-worship was general. With the systematic development of ethnic religions, in some instances ancestor-worship remained dominant, as with the Chinese, the Japanese, and the Romans; in others, a polytheism based upon nature-worship acquired supremacy, as with the Hindus and Greeks, and our own Teutonic forefathers. The great divinities of the Hellenic pantheon are all personifications of physical phenomena. At a comparatively late date the Roman adopted these divinities and paid to them a fashionable and literary homage, but his solemn and heartfelt rites were those with which he worshipped the lares and penates in the privacy of his home. His hospitable treatment of the gods of a vanquished people was the symptom of a commingling of the various local religions of antiquity which insured their mutual destruction and prepared the way for their absorption into a far grander and truer system.[8]