The preface includes this quote by Alexis de Tocqueville: "Nothing is more fertile than the art of being free, but nothing is harder than freedom's apprenticeship." (p.xii) This highlights the purpose of this book -- to describe and analyze the issues that have arisen in the post-aristocratic world of modern times. Liberty is nearly universally valued as a good thing, but defining what liberty really is and applying it correctly has produced much more difficulty. Gregg's book is a short but fruitful tour of the competing theories on how to preserve the liberty everyone so desires.
The first six chapters are organized by function: the first two chapters provide some philosophical background on the topic; the third chapter analyzes what people are talking about when they speak of liberty ("freedom to _____"); the fourth and fifth chapters concern how to make laws and establish a state, respectively, to preserve these rights; the sixth chapter discusses the role of nongovernmental associations and the importance of providing a check against the state's power if necessary.
Throughout these chapters, the same types of issues permeate the discussion. Does liberty carry with it a moral obligation to be virtuous and to require it of others? Is an appeal to an absolute standard of truth necessary in order to make the case for liberty? If the answers are yes, then what virtues or truths should they be? Can we rely on our human nature and capabilities as a guideline, or do we have to tailor our government to assume that left to our own devices, we will destroy ourselves? What principles do we use to mark out a position in between? Although ordered liberty is most associated with a question of designing an optimal government, this necessarily carries some assumptions about the nature of mankind, and this is not left out of the discussion.
The last chapter is a more informal and personal one, one in which the author discusses how the Catholic Church and individual Catholics should engage in the public debate, as well as the danger of having public policy expressed by people of faith disqualified because their motivations are labeled as religious in nature.
This is a good gateway book, complete with endnotes at the end of each chapter for further exploration.