 Plato was committed to both of these theses. By contrast, the Pythagoreans endorsed only the latter thesis. This is so at least if we trust Aristotle’s report (Metaphysics 987b23–987b25). Although Pythagoreanism considers numbers to be the causes and principles of all other existing things, it does not treat numbers as entities that are necessarily separate from matter (Zhmud 1989; De Smet 2022). From our perspective today, this is to some extent surprising because, compared to  (PM),  (SM) seems to enjoy more prima facie plausibility. But precisely because of the presence of strong tendencies towards Pythagoreanism in early Islamic thought (Brentjes 2022), (PM) was more explicitly defended than (SM). In any case, Avicenna’s brutal criticism of these two theses (along with his more general criticism of the Platonic theory of separate universal forms) made Pythagoreanism and Platonism extremely unpopular in post-Avicennian philosophy. In the Metaphysics of “The Healing”, Avicenna (d. 937) argues against (SM) and (PM) not only by rejecting arguments attributed to the defenders of these two theses (Avicenna [Mph]: chap. VII.2) but also by developing his own positive arguments against them (Avicenna [MPh]: chap. VII.3).