We started from some of the ascertained facts of savage thought and savage life. The doctrine of Spirits formed our first proposition. This we defined to be the belief held by savages that man consists of body and spirit; that it is possible for the spirit to quit the body and roam at will in different shapes about the world, returning to the body as to its natural home; that in the spirit's absence the body sleeps, and that it dies if the spirit return not; further, that the universe swarms with spirits embodied and disembodied, because everything in the world has a spirit, and all these spirits are analogues of the human spirit, having the same will and acting from the same motives; and that if by chance any of these spirits be ejected from its body, it may continue to exist without a body, or it may find and enter a new body, not necessarily such an one as it occupied before, but one quite different. The doctrine of Transformation was another of our premises: that is to say, the belief held by savages in the possibility of a change of form while preserving the same identity. A third premise was the belief in Witchcraft, or the power of certain persons to cause the transformations just mentioned, and to perform by means of spells, or symbolic actions and mystical words, various other feats beyond ordinary human power. And there were others to which I need not now refer, all of which were assumed to be expressed in the tales and songs, and in the social and political institutions, of savages. Along with these, we assumed the hypothesis of the evolution of civilization from savagery. By this I mean that just as the higher orders of animal and vegetable life have been developed from germs which appeared on this planet incalculable ages ago; so during a past of unknown length the civilization of the highest races of men has been gradually evolving through the various stages of savagery and barbarism up to what we know it to-day; and so every nation, no matter how barbarous, has arisen from a lower stage than that in which it is found, and is on its way, if left to its natural processes, to something higher and better. This is an hypothesis which does not, of course, exclude the possibility of temporary and partial relapses, such as we know have taken place in the history of every civilized country, any more than it excludes the possibility of the decay and death of empires; but upon the whole it claims that progress and not retrogression is the law of human society. The different stages of this progress have everywhere left their mark on the tales and songs, the sayings and superstitions, the social, religious and political institutions--in other words, on the belief and practice--of mankind.