Depressive disorders have been around right from the the beginning of recorded history. Hippocrates referred to depression as melancholia, which literally means black bile. Black bile, along with blood, phlegm, and yellow bile were the four humors (fluids) that accounted for the basic medical physiology of that time. Depression has been portrayed in literature and the arts for hundreds of years. In the 19th century, depression was seen as an inherited weakness of temperamen.