 Avempace affirms that the five predicables are not primitive concepts, but constitute correlations between two universals falling within the rules of individuals and classes. He says: “Genus, species, property and accident are correlates (iḍafa) which are inherent to the intelligibles regarding the quantity of their subjects” (IB-taaliq: 50). Genus, species and property are essences inhering in a shared subject; by contrast, the accident is not an essence and exists outside the subject. The specific difference is related only to the individual and may be grasped without reference to the universal.