Meanwhile, the concept of personality, just like the concepts of substance and of the simple, can remain (insofar as it is merely transcen dental,.e., a unity of the subject which is otherwise unknown to us, but in whose determinations there is a thoroughgoing connection of apper ception), and to this extent this concept is also necessary and sufficient for practical use; but we can never boast of it as an extension of our self knowledgea through pure reason, which dazzles us with the uninter rupted continuous duration of the subject drawn from the mere concept of the identical self, since this concept merely revolves in a circle around itself and brings us no farther in regard to even one single question about synthetic cognition.