Mark Doty has always felt haunted by Walt Whitman's bold, perennially new American voice, and by his equally radical claims about body and soul and what it means to be a self. In What Is the Grass, Doty--a poet, a New Yorker, and an American--keeps company with Whitman and his Leaves of Grass, tracing the resonances between his own experience and the legendary poet's life and work. What is it then between us? Whitman asks. In search of an...