THE DOORS of PERCEPTION It was in 1886 that the German pharmacologist, Louis Lewin, published the first systematic study of the cactus, to which his own name was subsequently given. Anhalonium lewinii was new to science. To primitive religion and the Indians of Mexico and the American Southwest it was a friend of immemorially long standing. Indeed, it was much more than a friend. In the words of one of the early Spanish visitors to the New World, "they eat a root which they call peyote, and which they venerate as though it were a deity." Why they should have venerated it as a deity became apparent when such eminent psychologists as Jaensch, Havelock Ellis and Weir Mitchell began their experiments with mescalin, the active principle of peyote. True, they stopped short at a point well this side of idolatry; but all concurred in assigning to mescalin a position among drugs of unique distinction. Administered in suitable doses, it changes the quality of consciousness more profoundly and yet is less toxic than any other substance in the pharmacologist's repertory. Mescalin research has been going on sporadically ever since the days of Lewin and Havelock Ellis. Chemists have not merely isolated the alkaloid; they have learned how to synthesize it, so that the supply no longer depends on the sparse and intermittent crop of a desert cactus. Alienists have dosed themselves with mescalin in the hope thereby of coming to a better, a first-hand, understanding of their patients' mental processes. Working unfortunately upon too few subjects within too narrow a range of circumstances, psychologists have observed and catalogued some of the drug's more striking effects. Neurologists and physiologists have found out something about the mechanism of its action upon the central nervous system. And at least one Professional philosopher has taken mescalin for the light it may throw on such ancient, unsolved riddles as the place of mind in nature and the relationship between brain and consciousness.