"I believe that Luhmann is the only true genius in the social sciences alive today. By this, I mean that not only is he smart, extremely productive, and amazingly erudite, though all this is true enough, but also that he has, in the course of an improbable career, elaborated a theory of the social that completely reinvents sociology and destroys its most cherished dogmas." So wrote Stephen Fuchs in his Contemporary Sociology review of Luhmann's major theoretical work, Social Systems (Stanford, 1995). In this volume, Luhmann analyzes the evolution of love in Western Europe from...