Obsession: Or, How Evil Spirits Influence Mortals

Obsession is the irregular or perverted action of the natural law, existing between spiritual and physical life. This law, understood and utilized for beneficent purposes, is that which gives to man, the idea of immortality; but perverted in its action by the ignorance and often by the design of those using it for selfish ends, produces intense mental suffering and often moral obliquity upon those who do not know of its existence or the real source of their troubles.