Natural conflict

Rossellini even said that you shouldn't write scripts -- only swine write scripts -- that the conflict in a film should simply emerge from the facts. A character from a given place at a given time is confronted by another character from a very different place: and voilá, there exists a natural conflict between them and you start from that. There's no need to invent anything.

-- Francois Truffaut, interviewed in 1984,
just reprinted in the New Yorker