Before leaving the subject of mediums I must allude again to witchcraft. To those who believe in spirits, good or evil, which can take possession of us and make us do their will, and can throw about bricks and sand and furniture in our material world, there is nothing remarkable in epidemics of bewitchery, especially as the witch-finders were more fortunate than our spiritualists in having the unanimous support of the most eminent authorities of their day. To explain the psychology of witchcraft is beyond the scope of this book, but it is not hard to conceive that when the belief in witchcraft was strong certain unfortunate people who set out to play tricks, maybe for notoriety or temporary gain, became ensnared by credulity and finding escape difficult came to believe in their own powers. Thus dissociation would be set up and on the side of the witch-finders Herd Instinct (or suggestion) and logic-tight compartments did the rest. The fact that confessions of witchcraft were apparently common makes this explanation more probable. For a career ending at the stake to have such a trivial origin as a desire for notoriety is in agreement with the history of Sludge, whose downfall began with a desire to draw attention to himself. Call them ambitions and the desires seem less trivial, nor do I shrink from suggesting that the 'gifts' of the water-diviner and the most financially disinterested medium, even of Mr. Stainton Moses himself, have origin in a desire to shine before one's fellows--a neurotic 'Will to Power'. CONCLUSION Although I have emphasised the part that dissociation plays in the production of beliefs and actions, yet dissociation is only a particular manifestation of the unconscious and it is the latter which is becoming the field of research as to the causes of human action. From the evolutionary standpoint consciousness is a late development. Man sacrificed many advantages when he rose above the beast; in every mere bodily endowment he has superiors in the animal world, and as the influence of consciousness has become more and more important so the sphere of his unconscious actions has diminished. The bird needs no foresight for the building of her nest: the impulse to build comes and must be obeyed. When migration time arrives there is no reasoned plan of going to a distant land, no scheming of routes or destinations: she just goes. So it is with the intricate instincts of other creatures, of the wasp that builds her brood-cell, fills it with living victims, and places there an egg of whose future she can know nothing. Seeing these things we marvel at the intelligence of the agent, but the child who ties a rag round a stick and gives it a name uses more initiative than any other animal possesses. Here, rather late, I will introduce McDougall's definition of an instinct:--