This book examines mass murder in the twentieth century and explains how the elements of a genocidal mind can be perceived in behaviour, law, religion, philosophy, literature, and psychology. It outlines ways to exercise vigilance in all of these cultural arenas and develop an early warning system that can help prevent societies from going over the boundary from civility to genocide. If we wish to recognize the genocidal mentality, the authors maintain, we must reckon not only with the increased callousness of the killers but also with their misguided conviction that they were engaged in something constructive to humanity.