FRESH AIR “Song of Myself ” captures in a particular voice and at a particular moment something alive, generous, and hopeful in the developing culture of the United States, and it escaped, almost immediately, the bonds of its fervent nationalism: it became a way forward in the twentieth century for poets all over the world — in Latin America and Russia and Portugal and China and India and North Africa. For all its fame, the poem and the years during which it came into being are something of a mystery — one that has been studied by Whitman’s many biographers. […]