The Seventeenth Century: Harvey and Willis.
—It is known to all students of the history of medicine that what may be designated in general as the modern point of view regarding the cause of the heart beat dates from the work of William Harvey. Before his time physicians thought along the lines laid down by the ancient masters, in that they conceived the expansion of the heart in diastole to be an active, or rather the active phenomenon of the heart beat. This expansion was attributed to the innate or implanted heat, to the vital spirits, to the pulsatile force, etc. That the diastole of the heart is an active rather than a passive expansion has been held in a sense by many prominent physiologists, even in the nineteenth century. Magendie, for example, states that at first he entertained this belief. Nevertheless it remains true that Harvey's experiments
HOWELL WH. THE CAUSE OF THE HEART BEAT.. JAMA. 1906;XLVI(22):1665-1670. doi:10.1001/jama.1906.62510490009001b