 Instead, Crathorn treats the Aristotelian categories as philosophical conventions. Following the chapters of Aristotle’s Categories step by step, he comes to the conclusion that none of the ten categories are valid because the reasons Aristotle uses to distinguish them are inadequate. For example, the category of substance is distinguished from the other categories by the fact that it has no contrary and can successively acquire contrary qualities (Aristotle, Categories 5). But Crathorn claims that when we heat a piece of wood or a man, not only the substance but also its qualities become hot, such that its qualities change from one state to their contrary exactly like a substance. Therefore, this crucial distinction between substance and accidents does not apply. Crathorn writes, “not only the substance of the wood can receive the contraries, but also the accidents of the wood ... but if the wood is hot, not only is the heat attached to the wood hot, but also all the positive coextensive natures of the wood” (I Sent., q. 13, concl. 13). He also affirms that “one and the same thing numerically can truly be said to be substance and accident in relation to different things” (ibid., concl. 5). Indeed, water and fire can be considered as natural substances, but one is the contrary of the other. As a general conclusion, Crathorn asserts that the very same thing can be called a substance, a quality, a quantity, a relation and so forth (q. 17, p. 462 and q. 18, p. 476).