Love seems like the most personal experience, one that touches each of us in a unique way that is more personal than social, and hence it is not surprising that it has been largely neglected by sociologists and social theorists. While it has long been a central preoccupation of writers and novelists, love has rarely attracted anything more than the most cursory attention of social scientists.

This short text, originally written in 1969 by the eminent German social theorist Niklas Luhmann, goes a long way to redressing this neglect. Rather than seeing love as a unique and...