Black bile was, of course, associated with melancholy (literally, Greek melan-, black + chole, bile) and was thought to be produced by the spleen, a left-sided organ. For the same reasons the term spleen itself was, from the fourteenth century to the seventeenth
McGilchrist traces the etymological and humoral lineage connecting the spleen as a left-sided organ, black bile, and the historical English use of ‘spleen’ to denote melancholy, linking it to his broader argument about right-hemisphere dominance and mood.
, The Master and His Emissary: The Divided Brain and the Making of the Western World, 2009thesis