Music theorists of the thirteenth and fourteenth centuries borrowed concepts, terminology, and illustrations from tracts on anatomy, surgery, dissection, and treatment used at the medical schools in Paris, Bologna, and Padua. Arranged hierarchically according to function, location, and level of performance, internal organs, fluids, and systems were used in cleverly constructed parallels to clarify the meaning of music theory concepts for a readership that would have been quite familiar with contemporary medical lore.
Thus Perseus and Petrus discoursed on the brain, skull, the heart, and the arterial system to explain the structure of the medieval hexachord; Johannes Grocheio (Grocheo) dwelled on the respective functions of the heart, liver, and brain when prescribing composition rules for motets and organa; and Marchetto of Padua went to extreme interpretive lengths when describing the anatomy of the heart to clarify the role of proprietas in mensural notation.
