Ernst has said that anthroposophical medicine "includes some of the least plausible theories one could possibly imagine",[21] categorized it as "pure quackery",[2] and said that it "has no basis in science".[3] According to Quackwatch, anthroposophical medicine practitioners regard illness as a "rite of passage" necessary to purge spiritual impurities carried over from past lives, according to the precepts of "karmic destiny".[8]