Central in what Epicurus calls his view on nature are two theses: (1) there exist unchangeable imperceptible atoms that may, and do, join together to form perceptible compounds; (2) each atom has a finite number of minimal parts. With respect to the first thesis, there is uncertainty regarding Epicurus’ argument for it. With respect to the latter, there is uncertainty about both the thesis and therefore also the argument for it. I argue that this uncertainty is due to a confusion on two issues, which I aim to clear up. First, as everyone acknowledges, Epicurus’ arguments are formed as a response to Aristotle’s criticisms of classical Atomism. Skewed understanding of these criticisms obscures our understanding of Epicurus arguments. Second, though Epicurus says that these theses concern the nature of beings (φύσις τῶν ὄντων), they are mistakenly treated as being of physics.