AbstractObsession was introduced by Kraepelin in 1915 and has been studied extensively since. When a person with obsession becomes psysically exhausted with chronic rumination accompanied by suspicion, he or she is driven to impulsive acts, and develops a personality disorder that displays persistent abnormal activities. Obsession is related closely to depression and schizophrenia. Obsession is induced when uncertainty and instability dominates intelligence and creativity. The current social hierarchy of a strongly controlled society rejects diversity of humanity and often triggers personality disorders. This article reviews obsession and a myth as primitive mentality, normal and abnormal obsession, obsessionvspossession, society and obsession/ impulsion/degeneration, obsession and slowness/autism, a recent biological approach to obsession and a spectrum for obsession.