The Mask of Sanity: An Attempt to Clarify Some Issues About the So-Called Psychopathic Personality is a book written by American psychiatrist Hervey M. Cleckley, first published in 1941, describing Cleckley's clinical interviews with patients in a locked institution. The text is considered to be a seminal work and the most influential clinical description of psychopathy in the twentieth century. The basic elements of psychopathy outlined by Cleckley are still relevant today. The title refers to the normal "mask" that conceals the mental disorder of the psychopathic person in Cleckley's conceptualization.Cleckley describes the psychopathic person as outwardly a perfect mimic of a normally functioning person, able to mask or disguise the fundamental lack of internal personality structure, an internal chaos that results in repeatedly purposeful destructive behavior, often more self-destructive than destructive to others. Despite the seemingly sincere, intelligent, even charming external presentation, internally the psychopathic person does not have the ability to experience genuine emotions. Cleckley questions whether this mask of sanity is voluntarily assumed to intentionally hide the lack of internal structure, but concludes it hides a serious, but yet imprecisely unidentified, semantic neuropsychiatric defect. Six editions of the book were produced in total, the final shortly after his death. An expanded fifth edition of the book had been published in 1976 and was re-released by his heirs in 1988 for non-profit educational use. Source: Wikipedia (en)