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, as...