This book is a collection of essays (all by different authors) that serve both as biography and ideological summary for various political thinkers. The essays cover Plato, Aristotle, St. Augustine, St. Aquinas, Machiavelli, Jean Calvin, Thomas Hobbes, John Locke, Rousseau, Adam Smith, John Stuart Mill, Karl Marx, and two essays on modern thinkers that cover Bertrand Russell, RH Tawney, John Rawls, Herbert Marcuse, and Hannah Arendt.
This collection was a great introduction to political theory and, in general, the theories of the thinkers listed above. However, the way the book framed itself (as looking at the answer to the question 'Why should I obey the State') kind of missed the mark as to what the book actually was. I think this question was definitely addressed, but it was not the central point of the collection. Rather, it was that political thought has built on itself over the centuries and it seems to have begun out of a search for justice. In addition, some essays were worlds better than others in terms of summarizing or giving concrete examples of each thinker's ideas, but all essays were incredibly readable and accessible to a layperson. I think for me the purpose of the book was as a stepping stone to some basic ideas in political theory. Would I base a thesis on anything this book says? No. But it would definitely be helpful in directing you where to look.
Honestly, the only reason this didn't get a 4 was because certain essays (namely Machiavelli and Marx) seemed particularly devoid of a good ideological summary and instead were mostly biographical with vague assertions about their beliefs (at least as compared to essays on, say, Plato and Hobbes).