"From a scientific point of view, we can make no distinction between the man who eats little and sees heaven and the man who drinks much and sees snakes. Each is in an abnormal physical condition, and therefore has abnormal perceptions. Normal perceptions, since they have to be useful in the struggle for life, must have some correspondence with fact; but in abnormal perceptions there is no reason to expect such correspondence, and their testimony, therefore, cannot outweigh that of normal perception." Bertrand Russell, Religion and Science (New York: Oxford University Press), p. 188.