Among the Bantu-speakers of central and east Africa, waganga (ritual specialists) possess the esoteric knowledge of medicinal remedies and healing procedures, both natural and supernatural sort. Without this age-old knowledge, which is often passed on through the family line, the diagnosis, treatment, and healing processes would be ineffective. Although many objects used in the arts of healing are made by artists, the nganga's own contribution to the visual and medicinal effectiveness of the object is essential to the success of the healing process. Without the addition or accumulation of medicinal and symbolic substances, without the offerings of prayers, songs, and performance, without the strict adherence to long established steps of treatment--all of which are determined and prescribed by the healer--the objects would remain inanimate, void of any power or healing capabilities.