This book is a scholarly intervention in the debates within the Church around the question of "sexuality." It proposes that hot-button issues such as contraception, gay marriage, and the moral status of reproductive technologies are not merely debates about what we should or should not do in the privacy of our own homes; rather, these are matters with inevitable implications for the common good.

Using St. Augustine's two cities as a frame, the book explores the concepts of 'sexuality' and chastity. It argues that "sexuality" discourse is a carrier for two key modern impulses: self-invention and the desire for intimacy. Moreover, by associating "self-invention" with human dignity, "sexuality" discourse helps create a political society devoted to the promotion of personal autonomy as its end- a politics of the "earthly city." Chastity, by contrast, assumes that one must order his passions to fully realize his human nature. Since man is a political animal, chastity is consonant with a politics of the common good and a necessary condition of a true communion of persons- the social life of the "City of God."