The ability to walk on two legs over long distances distinguishes Homo sapiens from other primates, and indeed from every other species on earth. That ability has also yielded some of the best creative work of our species: the lyrical ballads of the English romantic poets, composed on long walks over hill and dale; the speculations of the peripatetic philosophers; the meditations of footloose Chinese and Japanese poets; the exhortations of and .
Rebecca Solnit, a thoughtful writer and spirite...