Recently scholars have been claiming that Aristotle’s biological explanations treat “facts about matter”—facts such as the degree of heat or amount of fluidity in an organism’s material constitution—as explanatorily basic or “primitive.” That is, these facts about matter are taken to be unexplained, brute facts about organisms, rather than ones that are explained by the organism’s form or essence, as we would have expected from Aristotle’s general commitment to the causal and explanatory priority of form over matter. In this paper, I present three considerations for rejecting the view that facts about matter are primitive. First, there is evidence that those putative unexplained facts about degrees of heat, dryness, fluidity, etc. are, in f...