 A natural way to think about modes is as a certain kind of property. The circular shape of the coin on the desk is a mode of that coin. On this reading, being circular is a state of the coin, a particularized way that the coin is. Spinoza’s claim that modes are “in” their substances also suggests that modes inhere in substances akin to the way that properties inhere in things, and that modes are therefore predicable of substances as subjects of predication. Circularity, we might say, inheres in the coin and the coin is circular. Of course, there is an extremely wide range of views about properties and property-bearers (see the entry on  properties), so claiming that modes are akin to properties that inhere in substances will not answer all questions. But even putting aside questions about inherence, property instantiation, and predication relations, it may seem like Spinoza has made a colossal blunder in Ip15. After all, how can a table or human being be anything like a property? How can I inhere in something else? What sense would it make to say of something — a substance — that it is Sam Newlandsish in the same sense in which I say of it that it is round? If there is such a thing as a “category mistake,” this may seem like an especially clear case of  one.[7]