The statements made concerning the fair names of the chief demons and devils which have haunted the imagination of mankind, heighten the contrast between their celestial origin and the functions attributed to them in their degraded forms. The theory of Dualism, representing a necessary stage in the mental development of every race, called for a supply of demons, and the supply came from the innumerable dethroned, outlawed, and fallen deities and angels which had followed the subjugation of races and their religions. But though their celestial origin might linger around them in some slight legend or characteristic as well as in their names, the evil phenomenon to which each was attached as an explanation assigned the real form and work with which he or she was associated in popular superstition. We therefore find in the demons in which men have believed a complete catalogue of the obstacles with which they have had to contend in the long struggle for existence. In the devils we discover equally the history of the moral and religious struggles through which priesthoods and churches have had to pass. And the relative extent of this or that particular class of demons or devils, and the intensity of belief in any class as shown in the number of survivals from it, will be found to reflect pretty faithfully the degree to which the special evil represented by it afflicted primitive man, as attested by other branches of pre-historic investigation. As to function, the demons we shall have to consider are those representing--1. Hunger; 2. Excessive Heat; 3. Excessive Cold; 4. Destructive elements and physical convulsions; 5. Destructive animals; 6. Human enemies; 7. The Barrenness of the Earth, as rock and desert; 8. Obstacles, as the river or mountain; 9. Illusion, seductive, invisible, and mysterious agents, causing delusions; 10. Darkness (especially when unusual), Dreams, Nightmare; 11. Disease; 12. Death.