Metaphysics, as Fârâbî understands it, is not about things in the categories but about the categories themselves and trans-categorial concepts such as being, unity, essence, cause, and God.
The class that contains all and only things that exist; proposed candidate for a highest kind.
categories(Kantian epistemology)
The most basic concepts of objects in general, which are unavoidably employed whenever we think about anything whatsoever
cause(Philosophical definition of causation requiring both sufficiency and necessity of the cause relative to its effect)
An event or state of things such that (a) if it happens or exists, the effect must happen or exist even if no further conditions are fulfilled, and (b) the effect cannot happen or exist unless the cause happens or exists.
essence(Medieval realist metaphysics)
The defining nature of a species, held by some to be distinct from and capable of surviving the destruction of all individual members of that species
metaphysics(Hartshorne's naturalistic redefinition of metaphysics)
On Hartshorne's view, the study not of realities beyond the physical, but of features of reality that are ubiquitous or that would exist in any possible world.
unity(Derived from being by adding the notion of indivision alone.)
Being that is undivided; the concept of being with the purely negative addition of indivision.
Where grammatical form tracks logical form, a non-paronymous noun will signify either a substance or a being in one of the nine Aristotelian categories of accidents, and a paronymous noun or a verb will signify that such a being is present in or attributed to some underlying subject. But metaphysics, as Fârâbî understands it, is not about things in the categories (Book of Letters I,11–17), but rather about the categories themselves (especially substance) and about trans-categorial concepts such