Written records have been describing extreme states of emotions since ancient Greece (Angst and Marneros, 2001), but Aretaeus of Cappadocia (which is geographically located in modern Turkey) was probably the first to outline the close relationship between depression and mania nearly 2000 years ago: “I think that melancholia is the beginning and a part of mania. . . The development of mania is really a worsening of the disease rather than a change into another disease. . . In most of them the sadness became better after various lengths of time and changed into happiness; the patients then developed a mania” (Angst and Marneros, 2001). Limited progress in our understanding of these extreme states of affect occurred until the mid-1800s, when both German and French physicians suggested that the change from melancholia to mania was not only “usual,” but that the continuous cycle between depression, mania, and disease free intervals were the key features of a mental disorder. Jean Pierre Falret named the disorder “folie circulaire” (1851), while Jules Baillarger called it “folie a double-form” (1854).