1840s: Mental illness is thought to be related to immoral behavior or the physical degeneration of the central nervous system. Insanity is thought to be the result of such diseases as syphilis.

1990s: After years of institutionalizing mentally ill patients and subjecting them to electroshock therapy, modern treatment of mental illness such as depression, bi-polar disorder, and schizophrenia include counseling and drug therapy.

1840s: "The Tell-Tale Heart" is published in 1843. The story is a psychological thriller that invites the reader into the world of the narrator's insanity. Other examples of Poe's eerie, macabre

style include "The Pit and the Pendulum," written in 1842, which explores the dark side of human nature and features both cruelty and torture.

1990s: People continue to be fascinated by the dark side of humanity. The popular film Silence of the Lambs examines the psychological motivations of a serial killer. Best-selling...