I'm a professor of English at Barnard College, Columbia University, in New York, where I teach a course called "Walk This Way." In it, we explore the cultural history of walking, from peripatetic philosophers to contemporary performance art. My own walking, mostly in Europe and the US, is a random patchwork of streets and trails, with a few mountains thrown in. My new book, "The Art of Walking: A History in 100 Images," looks at how Western Art and images of the walker have evolved in tandem; a new way of walking is often linked to a new way of representing people on the move.