 Bertrand Russell (1935, 188) once quipped that “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.” C.D. Broad (1935, 164) wrote, to the contrary, “One might need to be slightly ‘cracked’ in order to have some peep-holes into the super-sensible world.” Thus, the issue is engaged whether we can explain away religious and mystical experiences by reference to natural causes. Can science “explain away” mystical experiences by showing that “It’s all in the head”?