"You show me ten men who cherish some religious doctrine or political ideology, and I’ll show you nine men whose minds are utterly impervious to any factual evidence which contradicts their beliefs, and who regard the producer of such evidence as a criminal who ought to be suppressed. For instance, on the Fourth Level Europo-American Sector, where I was just working, there is a political sect, the Communists, who, in the territory under their control, forbid the teaching of certain well-established facts of genetics and heredity, because those facts do not fit the world picture demanded by their political doctrines. And on the same sector, a religious sect recently tried, in some sections successfully, to outlaw of the teaching of evolution by natural selection."