A shaman and visionary--not a poet in any ordinary sense--Mar a Sabina lived out her life in the Oaxacan mountain village of Huautla de Jim nez, and yet her words, always sung or spoken, have carried far and wide, a principal instance and a powerful reminder of how poetry can arise in a context far removed from literature as such. Seeking cures through language--with the help of Psilocybe mushrooms, said to be the source of language itself--she was,...