This book provides a re-interpretation of the terms "realism" and "idealism" in international relations, and a critical examination of key figures in international theory: Hans Morgenthau, Kenneth Waltz and Hedley Bull. Morgenthau and Bull are traditionally regarded as the "Grand Theorists" of realism, but this book argues, contrary to conventional wisdom, that they could more properly be categorized as idealists. Griffiths' contention is that, in addition to imagination, nostalgia and complacency are also forms of political idealism. He argues that Morgenthau's work suffers from the shortcomings of "nostalgic idealism". In contrast, Hedley Bull's analysis of international society is based on a more realistic understanding of world politics.