In puzzling out Ayn Rand's opinions about Aristotle's theory of knowledge for my last essay on her ideas, I've been doing a bit of research on the Aristotelian tradition in philosophy (about which I've long wanted to write a history, although that large task is likely beyond my abilities). While reading Aristotle and the Renaissance by Charles B. Schmitt (Harvard University Press, 1983), I came across a passage that has provided some early confirmation of my long-held suspicion that Rand's perspective on Aristotle was in some way filtered through the Neoplatonic tradition (in this case by way of Thomas Aquinas):
Such tendencies to modify peripatetic doctrine by calling on external traditions continued throughout the Middle Ages. One particularly noteworthy example is Thomas Aquinas, whose metaphysics, as is now generally recognized, is more Neoplatonic than Aristotelian. While the external form and language of Thomas's exposition is largely Aristotelian, at the core there is a metaphysics of participation that has no genuine basis in Aristotle. It is, in fact, one of the central doctrines of Neoplatonism, which developed quite naturally from Plato's Theory of Forms with its consequent doctrine of participation. Though Thomas did not know Plotinus directly and knew the voluminous writings of Proclus only partially, he derived enough information from intermediate Latin and Arabic sources (especially the Liber de causis, which was then attributed to Aristotle) to allow him to formulate a metaphysical system eclectic to a degree which he himself probably did not realize. (p. 93)
Further research required...