ABSTRACT
The concept of mood disorders dates back to eternity. This long history of the emotions and their disorders has a fascinating journey. As with any history concerned with disease concepts, the conceptual history of mood disorders must be scrutinized through close attention to nosological texts in tracing how categories were created how they evolved over the time. This article covers the evolution of the concept of mood disorders and its journey from the Hippocratic era to the Kraepelin's dichotomization between dementia praecox (schizophrenia) and manic-depressive insanity (bipolar and unipolar disorders) and its culmination into the contemporary classifications of mood disorders. It also addresses the problem of boundaries between the different mood disorders in terms of their conceptualization and classification. The shortcomings of the classificatory systems and the current progress in the nosology have also been discussed.
