Karl Jaspers' Allgemeine psychopathologie appeared in 1913 when he was just 30 years old. Although he wrote next to nothing else on psychopathology in a long and distinguished career, his book remains one of the truly great achievements in the field. In it Jaspers sought to create a new methodology for the study of mental disorder—one that wholeheartedly embraced the human as well as the natural sciences: his approach to the description of delusion, for example, is evidence of its originality and power.