The Diagnostic and Statistical Manual of Mental Disorders and the International Statistical Classification of Diseases and Related Health Problems are the two main tools used in diagnosing mental illnesses. While it is debatable whether some of the apparent illnesses listed in these two classification systems should be registered as mental illnesses at all, it is indisputable that mental illness has scared and fascinated people for centuries. Anything from Schizophrenia to Bibliomania to Narcolepsy to Personality Disorders. I have no difference in interest regarding them.