  The best guide to the separation of Forms is the claim that each Form is what it is in its own right, each is an auto kath auto being. In asking ‘What is (the Form) F?’, Plato seeks what F is in a particular and special way: He seeks what F is independent from any of its material instances, and in some sense independent of anything else, whether another Form or the soul. What each Form is, what each Form is in its own right, it is in virtue of its essence, ousia. The connection between the Form and the essence being predicated of it is exhibited in the Republic's formula that a given on (being) is completely or perfectly (477ff), as well as the so-called self-predication statements. According to the predicationalist reading, the relation connecting an essence with that Form of which it is the essence is  Being (see Code 1986, esp. 425–9).  (I capitalize the ‘is’ used to represent the predication relation of Being, e.g., Justice Is just.) The predicate in such self-predication statements stands for the (real) definition of the Form, conveniently captured by Nehamas' ‘what it is to be  F’.[9]  Each Form, then Is its essence.