 The difficulties involved in Aristotle’s list of species in the category of quantity can be made more precise by noting that in several places he seems to commit himself to the view that body is a species in the category of substance (Top. 130b2, DC 2681–3, DA 434b12, Meta. 1079a31, 1069b38). And as I have drawn the genus-species structure in the category of substance above, body is one of the two species immediately under substance. Yet body also appears as a species under the species Continuous Quantity. The difficulty arises because Aristotle is committed to the view that no species can occur in both the category of substance and in some other category. For, he thinks that a species in substance is said-of primary substances while species in the other categories are not said-of primary substances. Hence, any species in both substance and some accidental category would be said-of and not said-of primary substance. Aristotle’s list of species in the Category of Quantity is thus not merely puzzling but seems to commit Aristotle to a contradiction. So, a second question about Aristotle’s category of quantity naturally suggests itself: how can body be a species in both the category of quantity and the category of substance? (Studtman 2002)