This dissertation is aimed at resolving a central tension in Aristotle’s account of value and goodness. It shows how Aristotle can at once hold that goodness is a species-specific property but also that certain species are better than others – e.g. why he thinks that to be good means something different for fish and for humans but at the same time that humans are better than fish. First, despite widespread assumptions to the contrary, comparisons do not require a univocal value in terms of which entities are compared and that Aristotle does not make such an assumption. Second, as a final cause, Aristotle’s prime mover is a normative standard according to which entities can be compared in terms of how close they come to approximating it, even as they do so in very different ways. Finally, there are normative implications of Aristotle’s view: his commitment to natural hierarchy is non-instrumental and does not license an exploitation of non-human animals or the environment.