Michael Scammell is the author of Solzhenitsyn: A Biography (W. W. Norton, 1986) and writes regularly for the New York Review of Books, New Republic, The New York Times Book Review, and other publications. His AGNI essay is an excerpt from his book Koestler: The Literary and Political Odyssey of a Twentieth Century Skeptic (Random House, 2009). (updated 6/2010)