Books V and VI of Aristotle's Politics constitute a manual on practical politics. In the fifth book Aristotle examines the causes of faction and constitutional change and suggests remedies for political instability. In the sixth book he offers practical advice to the statesman who wishes to establish, preserve, or reform a democracy or an oligarchy. He discusses many political issues, theoretical and practical, which are still widely debated today--revolution and reform, democracy and tyranny, freedom and equality. David Keyt presents a clear and accurate new translation of these books, together with a commentary which, though primarily philosophical, also supplies a key to Aristotle's many historical references. It is intended to guide readers towards a proper understanding of this classic text in the history of political thought, and does not assumes knowledge of Greek or of ancient history and politics.