also include the , restless spirits who died in bad circumstances and often seek revenge. Purity and impurity A key theme in Shinto is the avoidance of kegare ("pollution" or "impurity"), while ensuring harae ("purity"). In Japanese thought, humans are seen as fundamentally pure. Kegare is therefore seen as being a temporary condition that can be corrected through achieving harae. Rites of purification are conducted so as to restore an individual to "spiritual" health and render them useful to society. This notion of purity is present in many facets of Japanese culture, such as the focus it places on bathing. Purification is for instance regarded as important in preparation for the planting season, while performers of noh theatre undergo a purification rite before they carry out their performances. Among the things regarded as particular pollutants in Shinto are death, disease, witchcraft, the flaying alive of an animal, incest, bestiality, excrement, and blood associated with either menstruation or childbirth. To avoid kegare, priests and other practitioners may engage in abstinence and avoid various activities prior to a festival or ritual. Various words, termed imi-kotoba, are also regarded as taboo, and people avoid speaking them when at a shrine; these include shi (death), byō (illness), and shishi (meat). A purification ceremony known as misogi involves the use of fresh water, salt water, or salt to remove kegare. Full immersion in the sea is often regarded as the most ancient and efficacious form of purification. This act links with the mythological tale in which Izanagi immersed himself in the sea to purify himself after discovering his deceased wife; it was from this act that other kami sprang from his body. An alternative is immersion beneath a waterfall. Salt is often regarded as a purifying substance; some Shinto practitioners will for instance sprinkle salt on themselves after a funeral, while those running restaurants may put a small pile of salt outside before business commences each day. Fire, also, is perceived as a source of purification. The yaku-barai is a form of harae designed to prevent misfortune, while the oharae, or "ceremony of great purification", is often used for end-of-year purification rites, and is conducted twice a year at many shrines. Before the Meiji period, rites of purification were generally performed by onmyōji, a type of diviner whose practices derived from the Chinese yin and yang philosophy. Kannagara, morality, and ethics Shinto incorporates morality tales