One of the most influential poets of the twentieth century, Robert Lowell was also a prolific letter writer who corresponded with many of the remarkable writers and thinkers of his day, including Elizabeth Bishop, Ezra Pound, Hannah Arendt, William Carlos Williams, T. S. Eliot, Robert Frost, and Edmund Wilson. These letters, conversations in writing, document the evolution of Lowell's work and illuminate another side of the intimate life that was the subject of so many of his poems: his deep friendships with other writers; the manic-depressive illness he struggled to endure and understand; his marriages to three prose writers; and his engagement with politics and the antiwar movement of the 1960s. The Letters of Robert Lowell shows us, in many cases for the first time, the private thoughts and passions of a figure unrivaled in his influence on American letters.