Jacques Roger in his Life Sciences in Eighteenth-Century French Thought states the well documented fact that Harvey was a committed Aristotelian. Others have noted how remarkable it was that someone devoted to an approach to science that used 'souls' and 'faculties' as explanatory devices should be the one to espouse the paradigm changing idea of circulation, which rendered those modes of explanation obsolete. With Aristotle overthrown much of what followed Harvey's work for the next century and a half were various unsuccessful attempts to replace it with various chemical and mechanical systems. What I found most interesting was Roger's observation that "Harvey did not dismiss the idea of souls or faculties at work ... : they were something whose operations he observed. Unlike his colleagues, he did not believe it sufficient to reason about them in order to know them. But he did not judge them to be either absurd or ridiculous. He recognized the complexity of the facts and was not tempted to simplify them abusively, even in order to force some clarity into them. He did not, of course, see living matter as we do; but he knew well that it was only through observations that we would get to know the mechanism of the faculties. He knew that an “occult quality” was merely a property whose causes we did not know, yet he did not for all that believe we must despair of ever knowing them or that we should give up studying at least their effects. Attraction was also to be considered an occult quality, and Newton’s mentality would be exactly the same as Harvey’s."
Having spent some time studying the late eighteenth century French Vitalists, who seemed to be reviving Aristotle in order to address the shortcomings of mechanist systems in biology and medicine, I was very excited to think that they were rediscovering Harvey's wisdom as well.