This is a book about the political thought of Jean-Jacques Rousseau. Its aim is to explain why, for Rousseau, thinking about politics - whether as democratic sovereignty, representative government, institutionalised power, imaginative vision or a moment of decision - lay at the heart of what he called his "grand, sad system." This book tracks the gradual emergence of the various components of that system and describes the connections between them. The result is a new and fresh interpretation of one of Europe's most famous political thinkers, showing why Rousseau can be seen as one of the first theorists of the modern concept of civil society and a key source of the problematic modern idea of a federal system.