What principle describes the relationship between essential and particular qualities in Thomistic moderate realism?

In Thomistic moderate realism, the principle that describes the relationship between essential (universal) and particular qualities is that they are interdependent and cannot exist without each other. This view, influenced by the philosophy of Thomas Aquinas, posits that essence and existence are connected in such a way that an object's essence (what it is) requires manifestation in a particular form or instance (what it exists as in reality). Essential qualities provide the framework or the universals that define categories, while particular qualities are the manifestations of these essentials in specific entities.

For example, the essence of a "tree" includes qualities such as being a perennial plant with branches and leaves, but it only comes to existence when this essence is instantiated in specific tree species like oaks or pines. Therefore, one cannot conceive of the essence of "tree" without referencing actual trees that exhibit those essential qualities. This interdependence underscores the philosophy's view that universals and particulars cannot exist in isolation from each other; they require one another to fully represent reality.