Bertrand Russell on Controversy and Belief
The Quotable Bertrand Russell, Lee Eisler, ed. (Prometheus, 1993), p. 106.
It is the things for which there is no evidence that are believed with passion. "Nobody feels any passion about the multiplication table or about the existence of Cape Horn, because these matters are not doubtful. "But in matters of theology or political theory, where a rational man will hold that at best there is a slight balance of probability on one side or the other, people argue with passion and support their opinions by physical slavery imposed by armies and mental slavery imposed by schools.