Symbiosis (mutualism) appears in fiction, especially science fiction, as a plot device. It is distinguished from parasitism in fiction, a similar theme, by the mutual benefit to the organisms involved, whereas the parasite inflicts harm on its host. Fictional symbionts often confer special powers on their hosts.[36] After the Second World War, science fiction moved towards more mutualistic relationships, as in Ted White's 1970 By Furies Possessed, which viewed aliens positively.[36] In The Phantom Menace, Qui-Gon Jinn says microscopic lifeforms called midi-chlorians, inside all living cells, allow characters with enough of these symbionts in their cells to feel and use the Force.[38]