  By the early thirteenth century, an inclusive view, according to which Aristotle's Categories is about words, concepts, and things, became standard. This view, shared by almost everyone up to Ockham (Pini, 2003, 11–18), had two important results. First, it lent support to the belief that categories are legitimately studied in three disciplines: grammar, logic, and metaphysics, but especially in logic and metaphysics. Second, it suggested a certain isomorphism between language (words), thought (concepts), and reality (things). The second point was supported by at least two passages in Aristotle's writings. In On the Soul, Aristotle claims that “in the case of objects which involve no matter… speculative knowledge and its object are identical” (430a 3–4). And in the text of On Interpretation cited earlier (16a 4–8) a similar point is made.  Taken together, these texts suggest that in some ways language (words), thought (concepts), and reality (things) are like each other in important ways, a fact that explains their relations.