considered relevant to the welfare of a community in a given location. However, specific individuals may be directly affected by one of the nature spirits resident in rocks or trees or in natural forces such as wind or lightning. Ancestral spirits, especially those of recently deceased kin, must be honored with appropriate rituals if they are expected to look favorably on the enterprises of their descendants. Only some of these rituals are performed by the descent group as a whole. More frequently, they are performed by and on behalf of a segment of the group or an individual. In theory, nature spirits are not generally considered to have led a human existence, but there are exceptions. Occasionally, the spirits of local rulers or others are detached from specific descent groups or are considered to have the characteristics of other nature spirits in that they are resident in features of the landscape. The spirits of the ancestors of a kin group are looked to for assistance in economic and social matters, and some misfortunes—famine, poor crops, personal losses—are ascribed to failure to have performed the appropriate rituals or to having misbehaved in some other way. Not all misfortunes are attributed to ancestral or nature spirits, however. Many people believe that magical powers inhere in things and that these powers, though usually neutral, may be used malevolently to afflict others or to prevent others to deal with affliction, particularly illness and death. It is further thought that individuals, sometimes unconsciously and without the use of material or technical means, can bring illness or other affliction to human beings. Such persons, usually called witches, are thought to be marked by the presence of a substance in the stomach or other organ. The terms witch and sorcerer have been applied to those who use their power malevolently, and the distinction between the two is based in part on whether the power is inherited (witch) or acquired in exchange for something of value (sorcerer) — whether the power is mystical or technical and whether the power is used on one's (the witch's) own behalf or on behalf of others, at a price. In fact, this distinction is made only in some societies and may be linked to certain features of community social structures and associated with patterns of accusation—whether kin by blood or marriage or non-kin are held to be responsible. Individual difficulties are attributed