" Psychopaths have likely plagued mankind since the beginning, but they are still poorly understood. In the 1800s, as the fledgling field of psychology began classifying mental disorders, one group refused to fit. Every known psychosis was marked by a failure of reasoning or a debilitating ailment: paralyzing fear, hallucinations, voices, phobias, and so on. In 1885, the term psychopath was introduced to describe vicious human predators who were not deranged, delusional, or depressed. They just enjoyed being bad. "

― Dave Cullen , Columbine