Today's diagnostic criteria are based on consensus, however, they are still incomplete and being changed. These unstable but temporarily dogmatic criteria have been constraining the thinking of individual psychiatrists, and invalidating painful scientific achievements based on previous ones. The limitation of the criteria system appears especially clear concerning depression due to the ambiguity of its definition. Therefore, the aim of this article was to review the history of various concepts of depression and to compare this to today's tendency, which attempts to consolidate diversity. In addition to all Diagnostic and Statistical Manual (DSM), Internal Classification of Diseases (ICD)-9, ICD-9-CM, and ICD-10 were centrally discussed. Classic descriptions of depression were extracted from reviews of classic literature, and some salient concepts and the process by which they had been integrated, divided, and newly proposed was traced. The descriptions of depression whose prototype had been melancholia have experienced significant conceptual changes through DSM-IV and the most recent DSM-V ; they impose tasks that are yet to be resolved. Among them, whether various depressive syndromes are diverse phenotypes of one disorder or they all represent different disorders could be regarded as the most fundamental problem. In order to conduct fruitful studies and to ensure proper treatment of every patient, more precise nosologic understanding of depression must be pursued.
Classification ; Consensus ; Depression* ; Depressive Disorder ; Diagnostic and Statistical Manual of Mental Disorders ; Fruit ; Humans ; International Classification of Diseases ; Phenotype ; Psychiatry ; Thinking

Today's diagnostic criteria are based on consensus, however, they are still incomplete and being changed. These unstable but temporarily dogmatic criteria have been constraining the thinking of individual psychiatrists, and invalidating painful scientific achievements based on previous ones. The limitation of the criteria system appears especially clear concerning depression due to the ambiguity of its definition. Therefore, the aim of this article was to review the history of various concepts of depression and to compare this to today's tendency, which attempts to consolidate diversity. In addition to all Diagnostic and Statistical Manual (DSM), Internal Classification of Diseases (ICD)-9, ICD-9-CM, and ICD-10 were centrally discussed. Classic descriptions of depression were extracted from reviews of classic literature, and some salient concepts and the process by which they had been integrated, divided, and newly proposed was traced. The descriptions of depression whose prototype had been melancholia have experienced significant conceptual changes through DSM-IV and the most recent DSM-V ; they impose tasks that are yet to be resolved. Among them, whether various depressive syndromes are diverse phenotypes of one disorder or they all represent different disorders could be regarded as the most fundamental problem. In order to conduct fruitful studies and to ensure proper treatment of every patient, more precise nosologic understanding of depression must be pursued.
Classification ; Consensus ; Depression* ; Depressive Disorder ; Diagnostic and Statistical Manual of Mental Disorders ; Fruit ; Humans ; International Classification of Diseases ; Phenotype ; Psychiatry ; Thinking