the thing described is composed of those attributes which they call essential parts.
For example, they say that a human being is composed of animal and rational, or of animality and rationality. This composition is mental: the composite quiddity in the mind is composed of these elements, which are its parts. As for the reality existing externally, it is characterized by these attributes. Many of these thinkers, however, have confused mental existence with external existence. This error has frequently occurred in the statements of the philosophers. Their early representatives, such as the followers of Pythagoras, maintained that numbers abstracted from numbered things exist in external reality.
The followers of Plato maintain the existence of Platonic Forms: realities abstracted from particular entities in external reality. These realities accompany particular entities in external reality. They likewise affirmed intelligible substances—that is, abstract entities—such as matter and hyle, and, according to some of them, intellects and souls.
Another instance of this is their distinction between essential attributes, which are prior to the quiddity and from which species are composed, and which they call genera and differentiae; and accidental attributes inseparable from the quiddity, which they call properties and common accidents. These five are the universals: genus, differentia, species, common accident, and property.
This has given rise to errors in their “logic” and “metaphysics” through which many people have gone astray. Elsewhere we have drawn attention to this in greater detail than there is room for here. For this reason, the term “composite”