The answer which I propose to this question, and which is developed to some extent in the following chapters, is a psychological one. It is that the phenomenon proceeds from, and is a necessary accompaniment of, the growth of human Consciousness itself--its growth, namely, through the three great stages of its unfoldment. These stages are (1) that of the simple or animal consciousness, (2) that of SELF-consciousness, and (3) that of a third stage of consciousness which has not as yet been effectively named, but whose indications and precursive signs we here and there perceive in the rites and prophecies and mysteries of the early religions, and in the poetry and art and literature generally of the later civilizations. Though I do not expect or wish to catch Nature and History in the careful net of a phrase, yet I think that in the sequence from the above-mentioned first stage to the second, and then again in the sequence from the second to the third, there will be found a helpful explanation of the rites and aspirations of human religion. It is this idea, illustrated by details of ceremonial and so forth, which forms the main thesis of the present book. In this sequence of growth, Christianity enters as an episode, but no more than an episode. It does not amount to a disruption or dislocation of evolution. If it did, or if it stood as an unique or unclassifiable phenomenon (as some of its votaries contend), this would seem to be a misfortune--as it would obviously rob us of at any rate one promise of progress in the future. And the promise of something better than Paganism and better than Christianity is very precious. It is surely time that it should be fulfilled.