 Post-knowledge cognition is also rejected as a distinct category. Non-conceptual post-knowledge cognition is in particular held to be impossible. Indeed, any subsequent perception necessarily has a new object since the object of the previous perception, being a momentary particular, has already ceased to exist when the subsequent perception arises. More generally, a post-knowledge cognition would have no cognitive role, for its object would not be something that is to be understood; it is accordingly judged to amount to non-understanding.