A new edition of Robert Nozick’s Anarchy, State, and Utopia is available, and contains a foreword by Thomas Nagel. Nagel describes not just the main themes of the book but also the intellectual environment from which it grew, as well Nozick’s own particular strengths, which in turn provides a view of Nagel’s thoughts about how to do philosophy well. From the foreword, which you can read on Google Books:

Philosophy has always depended on the interaction and uneasy rivalry between the creative theoretical imagination, which tries to burst the boundaries of mental custom, and the disciplinary controls of logic and rational justification…