The real essence or nature of a thing; that which makes it the kind of thing that it is (sometimes opposed to haecceity which makes it the particular individual that it is). The what-ness of things is thus a universal, in the sense that many different particulars may share the same essential properties. Quidditative knowledge would be knowledge of the real essence or nature of something; according to dominant theological tradition we cannot have quidditative knowledge of God, but at best know things about Him or Her, in a topic-neutral way. See also abstraction, universals.