[Reconsideration of the "conversion theory" from the primacy of the heart to the primacy of the blood--William Harvey's observation, logic and the construction of the exercitatio].

In De motu cordis, W. Harvey sometimes waxes lyrical on the primacy of the heart. In his another treatise, De generatione, however, he insists on the primacy of the blood. The "conversion theory" explained this discrepancy with Harvey's conversion as caused by his discovery of the antiquity of the blood. But Whitterridge showed that Harvey had already described the antiquity of the blood in his earliest notebook, Prelectiones. As shown in this article, Harvey's observation was not a mere accidental discovery; based on the "classic questions", it was continuously and persistently conducted until he was assured of having seen the blood to exist prior to the pulse and movement to occur in the blood. While this crucial observation was not yet made in Prelectiones and De motu cordis, it was described as crucial evidence of the theory of the primacy of the blood in De generatione, in which this new theory was introduced as an independent topic of the exercitatio. The topic of the order of the generation was a crucial issue in the theoretical medicine of Harvey's days. That is, the Aristotelian primacy of the heart had been seriously challenged by the Galenic tripartite theory which pursued the antiquity of three organs. Harvey's theory, or the primacy of the blood, seems to consists with Aristotle's premise, in that it asserts the existance of the only source of all functions in living animals. Harvey's theory, however, was confronted, on the other hand, with Aristotle's another inconsistency, namely, the issue of two definitions about anima. We must consider the construction and strategy of the exercitatio in Harvey's days to understand the exact meaning of the primacy of the heart in De motu cordis. In De motu cordis, Harvey did not use the primacy of the heart in a central part of the exercitatio, namely, in confirming his unprecedented theory, the circulation of the blood, but he settled this Aristotelian premise in a marginal part, namely, in ratiocinating the final cause of the circulation and supporting his new theory from the sidelines.