 Aristotle’s account in Categories can, with some oversimplification, be expressed as follows. The primary substances are individual objects, and they can be contrasted with everything else—secondary substances and all other predicables—because they are not predicable of or attributable to anything else. Thus, Fido is a primary substance, and dog—the secondary substance—can be predicated of him. Fat, brown, and taller than Rover are also predicable of him, but in a rather different way from that in which dog is. Aristotle distinguishes between two kinds of predicables, namely those that are ‘said of’ objects and those that are ‘in’ objects. The interpretation of these expressions is, as usually with Aristotelian cruxes, very controversial, but a useful way of looking at it is as follows. Dog is said of Fido because it characterises him as a whole. Fat and the others are described as being in because they pick out a constituent feature that could be said to be, in a logical though not a physical sense, part of, or in him. Fido the individual is not attributable to any further thing at all.