 The interesting case is where something has properties that “remain so completely unmixed” that the items they characterize are different in property. Consider a form-matter composite in relation to its matter. The matter out of which a form-matter composite is made is essentially the same as the composite, since each is the entire material composite itself. Yet despite their essential sameness, they are not identical; the matter is not the composite, nor conversely. The matter is not the composite, for the composite comes to be out of the matter, but the matter does not come to be out of itself. The composite is not the matter, since “nothing is in any way a constitutive part of or naturally prior to itself.” Instead, the matter is prior to the composite since it has the property priority with respect to the composite, whereas the composite is posterior to its matter since it has the property posteriority with respect to its matter. Now despite being essentially the same, the matter is not characterized by posteriority, unlike the composite, and the composite is not characterized by priority, unlike the matter. Hence the matter and composite are different in property; the properties priority and posteriority are unmixed—they differ in property.