The Mask of SanityFirst published in 1941, "The Mask of Sanity: An Attempt to Clarify Some Issues About the So Called Psychopathic Personality" by Hervey M. Cleckley, an American psychiatrist, is considered to be the most important work on psychopathology of the twentieth century. Cleckley based his work on clinical interviews with patients in mental institutions and continued to edit and revise his seminal work throughout the years. The title "The Mask of Sanity"