On the occasion of its recent centennial, we trace the remarkable history of Herbert Spencer's 2,240 page Principles of Sociology , the most inductive, systematic, and comprehensive study of human society ever attempted. Spencer's bold aim was to establish empirically and then to explain (after the manner of the natural sciences) the 'relations of co-existence and sequence' among social phenomena. The database ('mass of evidence') required was so vast that it was published as a separate work, some eight folio volumes (...) called Descriptive Sociology . A major force in the making of both scientific sociology and anthropology in the last quarter of the nineteenth century, Spencer's magnum opus was all but lost to these fields by the early decades of the twentieth century. The present generation, however, is witnessing a growing revival of interest in Spencer's thought. For many, his confident vision of a natural science of society still offers the best hope for understanding human societies and how they have come to be as they are. (shrink)