One of their most sacred shrines was managed by the Nechisti, an order of monks. The shrine itself was protected by a natural force field which could cause massive neural damage to anyone who attempted to cross it unprepared. The Nechisti knew the method of crossing the field but did not easily share it.
In 2373, Kes encountered the field and fell into a coma. Captain Janeway went through the Nechisti rituals in an effort to save her. After three days of grueling trials and exposure to a hallucinogenic toxin, the captain believed she had the answer. However, it was only when she abandoned her scientific approach and embraced a blind faith that she successfully penetrated the field and returned Kes to health. (VOY: "Sacred Ground")