 Aquinas seems to see the species in the category of quality as unfolding systematically from some basic metaphysical principles. Whether Aquinas’s derivation of the species in the category of quality is plausible or whether some other derivation that stems from Aristotelian principles can be given has become the subject of recent scholarship (Kahm 2016, Studtmann 2003a). Although the issue may seem a local one pertaining only to Aristotle’s category of quality, it is in fact relevant to the larger issue, which I will discuss shortly, of Aristotle’s method of deriving the categories generally. A systematic derivation of Aristotle’s category of quality would give credence to the claim that Aristotle’s categorial scheme as a whole admits of some kind of systematic derivation.