APOTROPAIC CEREMONIES +138+. The savage and half-civilized belief (a belief that has survived to some extent in civilized communities) is that the ills that afflict or threaten a community (such as epidemics and shortage of crops) are due not to natural causes but to supernatural agencies. But man, it is held, may control the hostile supernatural agents--they are subject to fear and other emotions, and though powerful are not omnipotent; they may be expelled or otherwise got rid of--violence may be used against them, or the aid of stronger supernatural Powers may be called in. In pursuance of these ends ceremonies have been devised in many parts of the world; though differing in details they are alike in principle; the question is how man may become the master of the demons. The ceremonies are sometimes performed on the occasion of particular afflictions, sometimes are massed at stated seasons, as at the beginning of the year or in connection with some agricultural festival. +139+. Man's defensive attitude toward the supernatural world appears in many usages connected with ordinary life. Fear of the hostility of ghosts has led surviving friends to take precautions against their return--their own houses are closed to them and they are driven away with blows.[277] They are too near akin to be trusted, and they are believed to be able and willing to do harm.[278] At the other extreme of life, when the child comes into the world, mother and child must be guarded against hostile demonic influences.[279] When a demon is known to have entered into a human being, producing sickness or madness, exorcism must be resorted to; magicians, prophets, and saints are able by ceremonies or by prayer to expel the intruder and restore the afflicted to health. Ritual taint (which is supernatural), incurred, for example, by touching a dead body, is removed by sprinkling with sacred water.[280]