In 1953, in the presence of an investigator, Aldous Huxley took four-tenths of a gramme of mescalin, sat down and waited to see what would happen. When he opened his eyes everything, from the flowers in a vase to the creases in his trousers, was transformed. Huxley described his experience with breathtaking immediacy in The Doors of Perception. In its sequel Heaven and Hell, he goes on to explo...