As recently discovered letters from Kim Philby are published, John Gray argues that the spy's life illustrates why we are so poor at predicting the future. Where Philby saw a bright future in Soviet Communism - one that led him to betray friends and colleagues - many in the West hoped for a different utopia in Russia as Communism collapsed. Neither saw their dreams realised. As John Gray observes, both groups "failed to understand that the only genuine historical law is the law of irony."Producer: Adele Armstrong.